Support tests in freestanding

Summary:
Freestanding is *weird*. The standard allows it to differ in a bunch of odd
manners from regular C++, and the committee would like to improve that
situation. I'd like to make libc++ behave better with what freestanding should
be, so that it can be a tool we use in improving the standard. To do that we
need to try stuff out, both with "freestanding the language mode" and
"freestanding the library subset".

Let's start with the super basic: run the libc++ tests in freestanding, using
clang as the compiler, and see what works. The easiest hack to do this:

In utils/libcxx/test/config.py add:

  self.cxx.compile_flags += ['-ffreestanding']

Run the tests and they all fail.

Why? Because in freestanding `main` isn't special. This "not special" property
has two effects: main doesn't get mangled, and main isn't allowed to omit its
`return` statement. The first means main gets mangled and the linker can't
create a valid executable for us to test. The second means we spew out warnings
(ew) and the compiler doesn't insert the `return` we omitted, and main just
falls of the end and does whatever undefined behavior (if you're luck, ud2
leading to non-zero return code).

Let's start my work with the basics. This patch changes all libc++ tests to
declare `main` as `int main(int, char**` so it mangles consistently (enabling us
to declare another `extern "C"` main for freestanding which calls the mangled
one), and adds `return 0;` to all places where it was missing. This touches 6124
files, and I apologize.

The former was done with The Magic Of Sed.

The later was done with a (not quite correct but decent) clang tool:

  https://gist.github.com/jfbastien/793819ff360baa845483dde81170feed

This works for most tests, though I did have to adjust a few places when e.g.
the test runs with `-x c`, macros are used for main (such as for the filesystem
tests), etc.

Once this is in we can create a freestanding bot which will prevent further
regressions. After that, we can start the real work of supporting C++
freestanding fairly well in libc++.

<rdar://problem/47754795>

Reviewers: ldionne, mclow.lists, EricWF

Subscribers: christof, jkorous, dexonsmith, arphaman, miyuki, libcxx-commits

Differential Revision: https://reviews.llvm.org/D57624

llvm-svn: 353086

299 files changed, 893 insertions, 299 deletions

diff --git a/libcxx/test/std/utilities/time/date.time/ctime.pass.cpp b/libcxx/test/std/utilities/time/date.time/ctime.pass.cpp
index 3fa04b77999..ac29fd78180 100644
--- a/libcxx/test/std/utilities/time/date.time/ctime.pass.cpp
+++ b/libcxx/test/std/utilities/time/date.time/ctime.pass.cpp
@@ -29,7 +29,7 @@
 #pragma GCC diagnostic ignored "-Wformat-zero-length"
 #endif
 
-int main()
+int main(int, char**)
 {
     std::clock_t c = 0;
     std::size_t s = 0;
@@ -60,4 +60,6 @@ int main()
     static_assert((std::is_same<decltype(std::localtime(&t)), std::tm*>::value), "");
 #endif
     static_assert((std::is_same<decltype(std::strftime(str,s,"",&tm)), std::size_t>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/days.pass.cpp b/libcxx/test/std/utilities/time/days.pass.cpp
index a22f97b8f52..43b53ea33cb 100644
--- a/libcxx/test/std/utilities/time/days.pass.cpp
+++ b/libcxx/test/std/utilities/time/days.pass.cpp
@@ -15,7 +15,7 @@
 #include <type_traits>
 #include <limits>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::days D;
     typedef D::rep Rep;
@@ -24,4 +24,6 @@ int main()
     static_assert(std::is_integral<Rep>::value, "");
     static_assert(std::numeric_limits<Rep>::digits >= 25, "");
     static_assert(std::is_same_v<Period, std::ratio_multiply<std::ratio<24>, std::chrono::hours::period>>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/hours.pass.cpp b/libcxx/test/std/utilities/time/hours.pass.cpp
index e04888f2e2a..97fc2621b6a 100644
--- a/libcxx/test/std/utilities/time/hours.pass.cpp
+++ b/libcxx/test/std/utilities/time/hours.pass.cpp
@@ -14,7 +14,7 @@
 #include <type_traits>
 #include <limits>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::hours D;
     typedef D::rep Rep;
@@ -23,4 +23,6 @@ int main()
     static_assert(std::is_integral<Rep>::value, "");
     static_assert(std::numeric_limits<Rep>::digits >= 22, "");
     static_assert((std::is_same<Period, std::ratio<3600> >::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/microseconds.pass.cpp b/libcxx/test/std/utilities/time/microseconds.pass.cpp
index 20e12a9a288..ded1c22fe14 100644
--- a/libcxx/test/std/utilities/time/microseconds.pass.cpp
+++ b/libcxx/test/std/utilities/time/microseconds.pass.cpp
@@ -14,7 +14,7 @@
 #include <type_traits>
 #include <limits>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::microseconds D;
     typedef D::rep Rep;
@@ -23,4 +23,6 @@ int main()
     static_assert(std::is_integral<Rep>::value, "");
     static_assert(std::numeric_limits<Rep>::digits >= 54, "");
     static_assert((std::is_same<Period, std::micro>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/milliseconds.pass.cpp b/libcxx/test/std/utilities/time/milliseconds.pass.cpp
index 6183b929f19..b1fe99e1209 100644
--- a/libcxx/test/std/utilities/time/milliseconds.pass.cpp
+++ b/libcxx/test/std/utilities/time/milliseconds.pass.cpp
@@ -14,7 +14,7 @@
 #include <type_traits>
 #include <limits>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::milliseconds D;
     typedef D::rep Rep;
@@ -23,4 +23,6 @@ int main()
     static_assert(std::is_integral<Rep>::value, "");
     static_assert(std::numeric_limits<Rep>::digits >= 44, "");
     static_assert((std::is_same<Period, std::milli>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/minutes.pass.cpp b/libcxx/test/std/utilities/time/minutes.pass.cpp
index 413d8cd6f69..23f0bf2877d 100644
--- a/libcxx/test/std/utilities/time/minutes.pass.cpp
+++ b/libcxx/test/std/utilities/time/minutes.pass.cpp
@@ -14,7 +14,7 @@
 #include <type_traits>
 #include <limits>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::minutes D;
     typedef D::rep Rep;
@@ -23,4 +23,6 @@ int main()
     static_assert(std::is_integral<Rep>::value, "");
     static_assert(std::numeric_limits<Rep>::digits >= 28, "");
     static_assert((std::is_same<Period, std::ratio<60> >::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/months.pass.cpp b/libcxx/test/std/utilities/time/months.pass.cpp
index ff40823f1ea..b14b2fab533 100644
--- a/libcxx/test/std/utilities/time/months.pass.cpp
+++ b/libcxx/test/std/utilities/time/months.pass.cpp
@@ -16,7 +16,7 @@
 #include <type_traits>
 #include <limits>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::months D;
     typedef D::rep Rep;
@@ -25,4 +25,6 @@ int main()
     static_assert(std::is_integral<Rep>::value, "");
     static_assert(std::numeric_limits<Rep>::digits >= 20, "");
     static_assert(std::is_same_v<Period, std::ratio_divide<std::chrono::years::period, std::ratio<12>>>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/nanoseconds.pass.cpp b/libcxx/test/std/utilities/time/nanoseconds.pass.cpp
index c14389da728..d58a375c2a5 100644
--- a/libcxx/test/std/utilities/time/nanoseconds.pass.cpp
+++ b/libcxx/test/std/utilities/time/nanoseconds.pass.cpp
@@ -14,7 +14,7 @@
 #include <type_traits>
 #include <limits>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::nanoseconds D;
     typedef D::rep Rep;
@@ -23,4 +23,6 @@ int main()
     static_assert(std::is_integral<Rep>::value, "");
     static_assert(std::numeric_limits<Rep>::digits >= 63, "");
     static_assert((std::is_same<Period, std::nano>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/seconds.pass.cpp b/libcxx/test/std/utilities/time/seconds.pass.cpp
index bd2d6d2b3f5..45a3f1d8e7f 100644
--- a/libcxx/test/std/utilities/time/seconds.pass.cpp
+++ b/libcxx/test/std/utilities/time/seconds.pass.cpp
@@ -14,7 +14,7 @@
 #include <type_traits>
 #include <limits>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::seconds D;
     typedef D::rep Rep;
@@ -23,4 +23,6 @@ int main()
     static_assert(std::is_integral<Rep>::value, "");
     static_assert(std::numeric_limits<Rep>::digits >= 34, "");
     static_assert((std::is_same<Period, std::ratio<1> >::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/nothing_to_do.pass.cpp b/libcxx/test/std/utilities/time/time.cal/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/utilities/time/time.cal/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/ctor.pass.cpp
index 3a3978cb082..5c945fab75e 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/ctor.pass.cpp
@@ -23,7 +23,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using day = std::chrono::day;
 
@@ -42,4 +42,6 @@ int main()
         day day(i);
         assert(static_cast<unsigned>(day) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/decrement.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/decrement.pass.cpp
index c53af65112e..f5323f65956 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/decrement.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/decrement.pass.cpp
@@ -30,7 +30,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using day = std::chrono::day;
     ASSERT_NOEXCEPT(--(std::declval<day&>())  );
@@ -48,4 +48,6 @@ int main()
         assert(static_cast<unsigned>(day--) == i - 1);
         assert(static_cast<unsigned>(day)   == i - 2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/increment.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/increment.pass.cpp
index b26d2285aa4..0be8c847f30 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/increment.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/increment.pass.cpp
@@ -30,7 +30,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using day = std::chrono::day;
     ASSERT_NOEXCEPT(++(std::declval<day&>())  );
@@ -48,4 +48,6 @@ int main()
         assert(static_cast<unsigned>(day++) == i + 1);
         assert(static_cast<unsigned>(day)   == i + 2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/ok.pass.cpp
index 8a04298ab3c..131df7533c6 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using day = std::chrono::day;
     ASSERT_NOEXCEPT(                std::declval<const day>().ok());
@@ -33,4 +33,6 @@ int main()
         assert(day{i}.ok());
     for (unsigned i = 32; i <= 255; ++i)
         assert(!day{i}.ok());
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/plus_minus_equal.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/plus_minus_equal.pass.cpp
index 42f12af552e..d182d6c926f 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/plus_minus_equal.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.members/plus_minus_equal.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using day  = std::chrono::day;
     using days = std::chrono::days;
@@ -53,4 +53,6 @@ int main()
         assert(static_cast<unsigned>(day -= days{12}) == i + 10);
         assert(static_cast<unsigned>(day)             == i + 10);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/comparisons.pass.cpp
index 6b8a4277272..75bc4cf529a 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/comparisons.pass.cpp
@@ -23,7 +23,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using day = std::chrono::day;
 
@@ -40,4 +40,6 @@ int main()
     for (unsigned i = 1; i < 10; ++i)
         for (unsigned j = 1; j < 10; ++j)
             assert(testComparisons6Values<day>(i, j));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/literals.fail.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/literals.fail.cpp
index 36352fa35d6..6331bcf1b23 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/literals.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/literals.fail.cpp
@@ -20,8 +20,10 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using day = std::chrono::day;
     day d1 = 4d; // expected-error-re {{no matching literal operator for call to 'operator""d' {{.*}}}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/literals.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/literals.pass.cpp
index b3febd4ebe2..a887736f6e8 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/literals.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/literals.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     using namespace std::chrono;
@@ -43,4 +43,6 @@ int main()
     assert (d1 == std::chrono::day(4));
     }
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/minus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/minus.pass.cpp
index 4953d1afe4e..e8ade305adc 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/minus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/minus.pass.cpp
@@ -33,7 +33,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using day  = std::chrono::day;
     using days = std::chrono::days;
@@ -54,4 +54,6 @@ int main()
         assert(static_cast<unsigned>(d1) == 12 - i);
         assert(off.count() == static_cast<int>(12 - i)); // days is signed
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/plus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/plus.pass.cpp
index 10cec0a62d8..e219c7d3c7a 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/plus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/plus.pass.cpp
@@ -33,7 +33,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using day  = std::chrono::day;
     using days = std::chrono::days;
@@ -55,4 +55,6 @@ int main()
         assert(static_cast<unsigned>(d1) == i + 12);
         assert(static_cast<unsigned>(d2) == i + 12);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/streaming.pass.cpp
index ad3d4f3f9e6..23ce736c61d 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/time.cal.day.nonmembers/streaming.pass.cpp
@@ -48,8 +48,10 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
    using day = std::chrono::day;
    std::cout << day{1};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.day/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.day/types.pass.cpp
index d437a6ae3f4..3c26c57535f 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.day/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.day/types.pass.cpp
@@ -16,10 +16,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using day = std::chrono::day;
 
     static_assert(std::is_trivially_copyable_v<day>, "");
     static_assert(std::is_standard_layout_v<day>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.last/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.last/types.pass.cpp
index 10396919bd4..084a6aa8dc5 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.last/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.last/types.pass.cpp
@@ -21,7 +21,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using last_spec = std::chrono::last_spec;
 
@@ -29,4 +29,6 @@ int main()
 
     static_assert(std::is_trivially_copyable_v<last_spec>, "");
     static_assert(std::is_standard_layout_v<last_spec>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/ctor.pass.cpp
index f3dadd2f6b0..48642987a7c 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/ctor.pass.cpp
@@ -25,7 +25,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using day       = std::chrono::day;
     using month     = std::chrono::month;
@@ -43,4 +43,6 @@ int main()
     static_assert( md1.month() == std::chrono::January, "");
     static_assert( md1.day()   == day{4},               "");
     static_assert( md1.ok(),                            "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/day.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/day.pass.cpp
index c9c247d508f..7137433a9fb 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/day.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/day.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using day       = std::chrono::day;
     using month_day = std::chrono::month_day;
@@ -34,4 +34,6 @@ int main()
         month_day md(std::chrono::March, day{i});
         assert( static_cast<unsigned>(md.day()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/month.pass.cpp
index e1b46190f0a..b4744e6d4c7 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/month.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using day       = std::chrono::day;
     using month     = std::chrono::month;
@@ -35,4 +35,6 @@ int main()
         month_day md(month{i}, day{1});
         assert( static_cast<unsigned>(md.month()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/ok.pass.cpp
index 649f0996867..5e4c0082f5f 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.members/ok.pass.cpp
@@ -21,7 +21,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using day       = std::chrono::day;
     using month     = std::chrono::month;
@@ -51,4 +51,6 @@ int main()
 //  If the month is not ok, all the days are bad
     for (unsigned i = 1; i <= 35; ++i)
         assert(!(month_day{month{13}, day{i}}.ok()));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.nonmembers/comparisons.pass.cpp
index c186f594c64..d7e535a72e7 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.nonmembers/comparisons.pass.cpp
@@ -26,7 +26,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using day       = std::chrono::day;
     using month     = std::chrono::month;
@@ -66,4 +66,6 @@ int main()
                 month_day{month{2}, day{j}},
                 i == j, i < j )));
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.nonmembers/streaming.pass.cpp
index dbebdfa7d0e..8eef5f03095 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.md/time.cal.md.nonmembers/streaming.pass.cpp
@@ -31,10 +31,12 @@
 #include <iostream>
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month_day = std::chrono::month_day;
     using month     = std::chrono::month;
     using day       = std::chrono::day;
     std::cout << month_day{month{1}, day{1}};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.md/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.md/types.pass.cpp
index ba7c336a634..507855a990f 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.md/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.md/types.pass.cpp
@@ -16,10 +16,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month_day = std::chrono::month_day;
 
     static_assert(std::is_trivially_copyable_v<month_day>, "");
     static_assert(std::is_standard_layout_v<month_day>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/comparisons.pass.cpp
index ba9eda73a4a..265e7be372d 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/comparisons.pass.cpp
@@ -24,7 +24,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using month          = std::chrono::month;
     using month_day_last = std::chrono::month_day_last;
@@ -39,4 +39,6 @@ int main()
     for (unsigned i = 1; i < 12; ++i)
         for (unsigned j = 1; j < 12; ++j)
             assert((testComparisons6Values<month_day_last>(month{i}, month{j})));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/ctor.pass.cpp
index 4bf983f3b40..3696bb907d8 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/ctor.pass.cpp
@@ -23,7 +23,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month     = std::chrono::month;
     using month_day_last = std::chrono::month_day_last;
@@ -37,4 +37,6 @@ int main()
     constexpr month_day_last md1{std::chrono::January};
     static_assert( md1.month() == std::chrono::January, "");
     static_assert( md1.ok(),                            "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/month.pass.cpp
index b9945b6d88d..6bf75892da9 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/month.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month     = std::chrono::month;
     using month_day_last = std::chrono::month_day_last;
@@ -34,4 +34,6 @@ int main()
         month_day_last mdl(month{i});
         assert( static_cast<unsigned>(mdl.month()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/ok.pass.cpp
index 38c52e22958..730ab3b25d6 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month          = std::chrono::month;
     using month_day_last = std::chrono::month_day_last;
@@ -42,4 +42,6 @@ int main()
         month_day_last mdl{month{i}};
         assert(!mdl.ok());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/streaming.pass.cpp
index ebb91559854..1b4a8f108cb 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/streaming.pass.cpp
@@ -25,9 +25,11 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month_day_last = std::chrono::month_day_last;
     using month          = std::chrono::month;
     std::cout << month_day_last{month{1}};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/types.pass.cpp
index e3f02a88549..c6eebc42de1 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mdlast/types.pass.cpp
@@ -17,10 +17,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month_day_last = std::chrono::month_day_last;
 
     static_assert(std::is_trivially_copyable_v<month_day_last>, "");
     static_assert(std::is_standard_layout_v<month_day_last>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/ctor.pass.cpp
index d0ed4d37d01..6800a03e18a 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/ctor.pass.cpp
@@ -23,7 +23,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month = std::chrono::month;
 
@@ -42,4 +42,6 @@ int main()
         month m(i);
         assert(static_cast<unsigned>(m) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/decrement.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/decrement.pass.cpp
index 2cab328cfcb..6d7edc508c1 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/decrement.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/decrement.pass.cpp
@@ -30,7 +30,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using month = std::chrono::month;
 
@@ -49,4 +49,6 @@ int main()
         assert(static_cast<unsigned>(month--) == i - 1);
         assert(static_cast<unsigned>(month)   == i - 2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/increment.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/increment.pass.cpp
index 81162edf6ca..7bcd5bed716 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/increment.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/increment.pass.cpp
@@ -30,7 +30,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using month = std::chrono::month;
     ASSERT_NOEXCEPT(++(std::declval<month&>())  );
@@ -48,4 +48,6 @@ int main()
         assert(static_cast<unsigned>(month++) == i + 1);
         assert(static_cast<unsigned>(month)   == i + 2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/ok.pass.cpp
index 7cb5edad47f..a001c74a3fa 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month = std::chrono::month;
 
@@ -34,4 +34,6 @@ int main()
         assert(month{i}.ok());
     for (unsigned i = 13; i <= 255; ++i)
         assert(!month{i}.ok());
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/plus_minus_equal.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/plus_minus_equal.pass.cpp
index 7ca4a6e5f4c..a792072afa2 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/plus_minus_equal.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.members/plus_minus_equal.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using month  = std::chrono::month;
     using months = std::chrono::months;
@@ -63,4 +63,6 @@ int main()
         assert(static_cast<unsigned>(month -= months{ 9}) == static_cast<unsigned>(exp));
         assert(static_cast<unsigned>(month)               == static_cast<unsigned>(exp));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/comparisons.pass.cpp
index aa37fde3b29..f69fec8aaac 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/comparisons.pass.cpp
@@ -26,7 +26,7 @@
 #include "test_comparisons.h"
 
 
-int main()
+int main(int, char**)
 {
     using month = std::chrono::month;
 
@@ -43,4 +43,6 @@ int main()
     for (unsigned i = 1; i < 10; ++i)
         for (unsigned j = 10; j < 10; ++j)
             assert(testComparisons6Values<month>(i, j));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/literals.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/literals.pass.cpp
index 807cf29881b..9832fe37681 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/literals.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/literals.pass.cpp
@@ -29,7 +29,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 
     ASSERT_SAME_TYPE(const std::chrono::month, decltype(std::chrono::January));
@@ -83,4 +83,6 @@ int main()
     assert(static_cast<unsigned>(std::chrono::October)   == 10);
     assert(static_cast<unsigned>(std::chrono::November)  == 11);
     assert(static_cast<unsigned>(std::chrono::December)  == 12);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/minus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/minus.pass.cpp
index 291d299e3af..cda36412741 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/minus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/minus.pass.cpp
@@ -44,7 +44,7 @@ constexpr bool testConstexpr()
 
 #include <iostream>
 
-int main()
+int main(int, char**)
 {
     using month  = std::chrono::month;
     using months = std::chrono::months;
@@ -68,4 +68,6 @@ static_assert(testConstexpr<month, months>(), "");
         assert(static_cast<unsigned>(m1) == static_cast<unsigned>(exp));
 //          assert(off.count()               == static_cast<unsigned>(exp));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/plus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/plus.pass.cpp
index 87b39003b1e..58a951e1b0e 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/plus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/plus.pass.cpp
@@ -43,7 +43,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using month  = std::chrono::month;
     using months = std::chrono::months;
@@ -68,4 +68,6 @@ int main()
         assert(static_cast<unsigned>(m1) == exp);
         assert(static_cast<unsigned>(m2) == exp);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/streaming.pass.cpp
index 5f3f3884f6b..1d3aa7ce4e8 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.month/time.cal.month.nonmembers/streaming.pass.cpp
@@ -45,8 +45,10 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
    using month = std::chrono::month;
    std::cout << month{1};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.month/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.month/types.pass.cpp
index b3e5024656f..a6e67f10134 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.month/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.month/types.pass.cpp
@@ -16,10 +16,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month = std::chrono::month;
 
     static_assert(std::is_trivially_copyable_v<month>, "");
     static_assert(std::is_standard_layout_v<month>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/ctor.pass.cpp
index 8d0b560b1fd..8804e71e3e8 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/ctor.pass.cpp
@@ -24,7 +24,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month_weekday   = std::chrono::month_weekday;
     using month           = std::chrono::month;
@@ -42,4 +42,6 @@ int main()
     static_assert( md1.month() == std::chrono::January,                              "");
     static_assert( md1.weekday_indexed() == weekday_indexed{std::chrono::Friday, 4}, "");
     static_assert( md1.ok(),                                                         "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/month.pass.cpp
index 99bdcb1607c..35e7c83c792 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/month.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month_weekday   = std::chrono::month_weekday;
     using month           = std::chrono::month;
@@ -38,4 +38,6 @@ int main()
         month_weekday md(month{i}, weekday_indexed{Sunday, 1});
         assert( static_cast<unsigned>(md.month()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/ok.pass.cpp
index b4999652fd5..2ff1bf735f2 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month_weekday   = std::chrono::month_weekday;
     using month           = std::chrono::month;
@@ -47,4 +47,6 @@ int main()
 //  If the month is not ok, all the weekday_indexed are bad
     for (unsigned i = 1; i <= 10; ++i)
         assert(!(month_weekday{month{13}, weekday_indexed{Sunday, i}}.ok()));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/weekday_indexed.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/weekday_indexed.pass.cpp
index d80ae29d048..13a1bba53dd 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/weekday_indexed.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.members/weekday_indexed.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month_weekday   = std::chrono::month_weekday;
     using month           = std::chrono::month;
@@ -39,4 +39,6 @@ int main()
         assert( static_cast<unsigned>(md.weekday_indexed().weekday() == Sunday));
         assert( static_cast<unsigned>(md.weekday_indexed().index() == i));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.nonmembers/comparisons.pass.cpp
index 64df8840e74..46f756de06c 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.nonmembers/comparisons.pass.cpp
@@ -21,7 +21,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using month_weekday   = std::chrono::month_weekday;
     using month           = std::chrono::month;
@@ -82,4 +82,6 @@ int main()
                 month_weekday{month{2}, weekday_indexed{weekday{i}, 2}},
                 month_weekday{month{2}, weekday_indexed{weekday{j}, 2}},
                 i == j)));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.nonmembers/streaming.pass.cpp
index e7981b5713a..11a1d4ecd04 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/time.cal.mwd.nonmembers/streaming.pass.cpp
@@ -24,7 +24,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month_weekday   = std::chrono::month_weekday;
     using month           = std::chrono::month;
@@ -32,4 +32,6 @@ int main()
     using weekday         = std::chrono::weekday;
 
     std::cout << month_weekday{month{1}, weekday_indexed{weekday{3}, 3}};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/types.pass.cpp
index 67c3f17b946..bd4f4e1d492 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwd/types.pass.cpp
@@ -16,10 +16,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month_weekday = std::chrono::month_weekday;
 
     static_assert(std::is_trivially_copyable_v<month_weekday>, "");
     static_assert(std::is_standard_layout_v<month_weekday>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/ctor.pass.cpp
index fa5ca044358..d83bbe92f11 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/ctor.pass.cpp
@@ -27,7 +27,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month              = std::chrono::month;
     using weekday            = std::chrono::weekday;
@@ -56,4 +56,6 @@ int main()
     static_assert( mwdl3.month() == January,                         "");
     static_assert( mwdl3.weekday_last() == weekday_last{weekday{4}}, "");
     static_assert( mwdl3.ok(),                                       "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/month.pass.cpp
index 3561651c28a..a32b0899615 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/month.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month              = std::chrono::month;
     using weekday            = std::chrono::weekday;
@@ -38,4 +38,6 @@ int main()
         month_weekday_last mdl(month{i}, weekday_last{Tuesday});
         assert( static_cast<unsigned>(mdl.month()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/ok.pass.cpp
index 10245f938d6..02df5fbd22b 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month              = std::chrono::month;
     using weekday            = std::chrono::weekday;
@@ -48,4 +48,6 @@ int main()
         month_weekday_last mwdl{January, weekday_last{weekday{i}}};
         assert( mwdl.ok() == weekday_last{weekday{i}}.ok());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/weekday_last.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/weekday_last.pass.cpp
index 4afa6cca734..4ecf6d24628 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/weekday_last.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.members/weekday_last.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month              = std::chrono::month;
     using weekday            = std::chrono::weekday;
@@ -40,4 +40,6 @@ int main()
         month_weekday_last mdl(January, weekday_last{weekday{i}});
         assert( static_cast<unsigned>(mdl.weekday_last().weekday()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.nonmembers/comparisons.pass.cpp
index 4d0e935f11a..911693c25bf 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.nonmembers/comparisons.pass.cpp
@@ -24,7 +24,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using month              = std::chrono::month;
     using weekday_last       = std::chrono::weekday_last;
@@ -69,4 +69,6 @@ int main()
             month_weekday_last{month{1}, weekday_last{weekday{1}}},
             month_weekday_last{month{2}, weekday_last{weekday{2}}},
         false)));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.nonmembers/streaming.pass.cpp
index 2bf0e1ec43b..75654b1b3a2 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/time.cal.mwdlast.nonmembers/streaming.pass.cpp
@@ -25,7 +25,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month_weekday_last = std::chrono::month_weekday_last;
     using month              = std::chrono::month;
@@ -33,4 +33,6 @@ int main()
     using weekday_last       = std::chrono::weekday_last;
 
     std::cout << month_weekday_last{month{1}, weekday_last{weekday{3}}};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/types.pass.cpp
index 2271f42c031..2f2676d7a52 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.mwdlast/types.pass.cpp
@@ -17,10 +17,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month_weekday_last = std::chrono::month_weekday_last;
 
     static_assert(std::is_trivially_copyable_v<month_weekday_last>, "");
     static_assert(std::is_standard_layout_v<month_weekday_last>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_day.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_day.pass.cpp
index e51fb4fa47e..e9eb80bfd98 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_day.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_day.pass.cpp
@@ -38,7 +38,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using month_day = std::chrono::month_day;
     using month     = std::chrono::month;
@@ -104,4 +104,6 @@ int main()
                 assert(md1 == md2);
             }
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_day_last.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_day_last.pass.cpp
index 27043b88c63..84c2c6eaa39 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_day_last.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_day_last.pass.cpp
@@ -46,7 +46,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using month          = std::chrono::month;
     using month_day_last = std::chrono::month_day_last;
@@ -103,4 +103,6 @@ int main()
         }
     }
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_weekday.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_weekday.pass.cpp
index 4dc6db768e2..60b788de1e4 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_weekday.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_weekday.pass.cpp
@@ -44,7 +44,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using month_weekday   = std::chrono::month_weekday;
     using month           = std::chrono::month;
@@ -111,4 +111,6 @@ int main()
                     assert(mwd1 == mwd2);
                 }
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_weekday_last.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_weekday_last.pass.cpp
index 25d25b26d9b..07e5d8d75d6 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_weekday_last.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/month_weekday_last.pass.cpp
@@ -36,7 +36,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using month_weekday      = std::chrono::month_weekday;
     using month              = std::chrono::month;
@@ -103,4 +103,6 @@ int main()
                 assert(mwd1 == mwd2);
             }
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month.pass.cpp
index 6ef320ebb79..ba2b5c187f6 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month.pass.cpp
@@ -25,7 +25,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using month      = std::chrono::month;
     using year       = std::chrono::year;
@@ -64,4 +64,6 @@ int main()
                 assert(static_cast<unsigned>(ym.month()) == j);
             }
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_day.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_day.pass.cpp
index a8df7009632..a5aa4d0ef59 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_day.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_day.pass.cpp
@@ -42,7 +42,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using month          = std::chrono::month;
@@ -187,4 +187,6 @@ int main()
                 }
     }
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_day_last.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_day_last.pass.cpp
index 2556bb93f36..fd55e38b4c4 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_day_last.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_day_last.pass.cpp
@@ -38,7 +38,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using month               = std::chrono::month;
     using year_month          = std::chrono::year_month;
@@ -121,4 +121,6 @@ int main()
                 assert(ymdl1 == ymdl2);
             }
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_weekday.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_weekday.pass.cpp
index af27c945e09..4e71435805a 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_weekday.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_weekday.pass.cpp
@@ -37,7 +37,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using year_month         = std::chrono::year_month;
@@ -141,4 +141,6 @@ int main()
                         assert(ymd1 == ymd2);
                     }
      }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_weekday_last.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_weekday_last.pass.cpp
index ff467aa60c3..62b1f46765c 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_weekday_last.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.operators/year_month_weekday_last.pass.cpp
@@ -39,7 +39,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using year_month         = std::chrono::year_month;
     using year               = std::chrono::year;
@@ -149,4 +149,6 @@ int main()
                     assert(ymwdl1 == ymwdl2);
                 }
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/ctor.pass.cpp
index b9facef63e7..4a64b932b68 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/ctor.pass.cpp
@@ -26,7 +26,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday  = std::chrono::weekday;
     using weekday_indexed = std::chrono::weekday_indexed;
@@ -57,4 +57,6 @@ int main()
         weekday_indexed wdi(std::chrono::Tuesday, i);
         assert(!wdi.ok());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/index.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/index.pass.cpp
index 043a98accf5..4942f716480 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/index.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/index.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday         = std::chrono::weekday;
     using weekday_indexed = std::chrono::weekday_indexed;
@@ -34,4 +34,6 @@ int main()
         weekday_indexed wdi(weekday{2}, i);
         assert( static_cast<unsigned>(wdi.index()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/ok.pass.cpp
index 1cdfb29c96e..a2b5b48e4fc 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday         = std::chrono::weekday;
     using weekday_indexed = std::chrono::weekday_indexed;
@@ -45,4 +45,6 @@ int main()
 
 //  Not a valid weekday
     assert(!(weekday_indexed(weekday{9U}, 1).ok()));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/weekday.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/weekday.pass.cpp
index 47f50b6d672..e9c204d08b1 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/weekday.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.members/weekday.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday         = std::chrono::weekday;
     using weekday_indexed = std::chrono::weekday_indexed;
@@ -35,4 +35,6 @@ int main()
         weekday_indexed wdi(weekday{i}, 2);
         assert( static_cast<unsigned>(wdi.weekday()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.nonmembers/comparisons.pass.cpp
index 963f9f15ec8..104c59abf78 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.nonmembers/comparisons.pass.cpp
@@ -22,7 +22,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using weekday         = std::chrono::weekday;
     using weekday_indexed = std::chrono::weekday_indexed;
@@ -44,4 +44,6 @@ int main()
     static_assert( (weekday_indexed{weekday{1}, 2} != weekday_indexed{weekday{1}, 1}), "");
     static_assert(!(weekday_indexed{weekday{1}, 2} == weekday_indexed{weekday{2}, 2}),  "");
     static_assert( (weekday_indexed{weekday{1}, 2} != weekday_indexed{weekday{2}, 2}),  "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.nonmembers/streaming.pass.cpp
index 810b2cb0c49..5052a182458 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/time.cal.wdidx.nonmembers/streaming.pass.cpp
@@ -26,10 +26,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday_indexed = std::chrono::weekday_indexed;
     using weekday         = std::chrono::weekday;
 
     std::cout << weekday_indexed{weekday{3}};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/types.pass.cpp
index 74634da8a58..260b50f465d 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdidx/types.pass.cpp
@@ -16,10 +16,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday_indexed = std::chrono::weekday_indexed;
 
     static_assert(std::is_trivially_copyable_v<weekday_indexed>, "");
     static_assert(std::is_standard_layout_v<weekday_indexed>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.members/ctor.pass.cpp
index f7fa6632041..a569144d068 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.members/ctor.pass.cpp
@@ -23,7 +23,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday      = std::chrono::weekday;
     using weekday_last = std::chrono::weekday_last;
@@ -43,4 +43,6 @@ int main()
         weekday_last wdl{weekday{i}};
         assert(wdl.weekday() == weekday{i});
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.members/ok.pass.cpp
index d708a812463..eb0636aa9cf 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.members/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday      = std::chrono::weekday;
     using weekday_last = std::chrono::weekday_last;
@@ -33,4 +33,6 @@ int main()
 
     for (unsigned i = 0; i <= 255; ++i)
         assert(weekday_last{weekday{i}}.ok() == weekday{i}.ok());
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.members/weekday.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.members/weekday.pass.cpp
index 48767b3b86e..c5eb6e13201 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.members/weekday.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.members/weekday.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday      = std::chrono::weekday;
     using weekday_last = std::chrono::weekday_last;
@@ -29,4 +29,6 @@ int main()
 
     for (unsigned i = 0; i <= 255; ++i)
         assert(weekday_last{weekday{i}}.weekday() == weekday{i});
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.nonmembers/comparisons.pass.cpp
index 1a9fc97eb51..c5ca36e8288 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.nonmembers/comparisons.pass.cpp
@@ -21,7 +21,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using weekday      = std::chrono::weekday;
     using weekday_last = std::chrono::weekday_last;
@@ -39,4 +39,6 @@ int main()
     for (unsigned i = 0; i < 6; ++i)
         for (unsigned j = 0; j < 6; ++j)
             assert(testComparisons2Values<weekday_last>(weekday{i}, weekday{j}));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.nonmembers/streaming.pass.cpp
index efb59847255..85a40a3dc4c 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/time.cal.wdlast.nonmembers/streaming.pass.cpp
@@ -24,10 +24,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
    using weekday_last = std::chrono::weekday_last;
    using weekday      = std::chrono::weekday;
 
    std::cout << weekday_last{weekday{3}};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/types.pass.cpp
index c986f99c332..ff9d54f88da 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.wdlast/types.pass.cpp
@@ -16,10 +16,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday_last = std::chrono::weekday_last;
 
     static_assert(std::is_trivially_copyable_v<weekday_last>, "");
     static_assert(std::is_standard_layout_v<weekday_last>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ctor.local_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ctor.local_days.pass.cpp
index ee241c8e7c9..06656fb442a 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ctor.local_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ctor.local_days.pass.cpp
@@ -29,7 +29,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using local_days = std::chrono::local_days;
     using days       = std::chrono::days;
@@ -69,4 +69,6 @@ int main()
     assert( wd.ok());
     assert(static_cast<unsigned>(wd) == 3);
     }
+
+    return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ctor.pass.cpp
index 9ec3afb2144..470b9d79d23 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ctor.pass.cpp
@@ -26,7 +26,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday = std::chrono::weekday;
 
@@ -47,4 +47,6 @@ int main()
     }
 
 // TODO - sys_days and local_days ctor tests
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ctor.sys_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ctor.sys_days.pass.cpp
index 920b53e783c..e00184a9915 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ctor.sys_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ctor.sys_days.pass.cpp
@@ -29,7 +29,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using sys_days  = std::chrono::sys_days;
     using days      = std::chrono::days;
@@ -69,4 +69,6 @@ int main()
     assert( wd.ok());
     assert(static_cast<unsigned>(wd) == 3);
     }
+
+    return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/decrement.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/decrement.pass.cpp
index c8b023a37c5..d574e1db9b6 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/decrement.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/decrement.pass.cpp
@@ -31,7 +31,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using weekday = std::chrono::weekday;
     ASSERT_NOEXCEPT(--(std::declval<weekday&>())  );
@@ -49,4 +49,6 @@ int main()
         assert((static_cast<unsigned>(wd--) == euclidian_subtraction<unsigned, 0, 6>(i, 1)));
         assert((static_cast<unsigned>(wd)   == euclidian_subtraction<unsigned, 0, 6>(i, 2)));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/increment.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/increment.pass.cpp
index d9239ff8f90..bb62e0120ef 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/increment.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/increment.pass.cpp
@@ -31,7 +31,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using weekday = std::chrono::weekday;
     ASSERT_NOEXCEPT(++(std::declval<weekday&>())  );
@@ -49,4 +49,6 @@ int main()
         assert((static_cast<unsigned>(wd++) == euclidian_addition<unsigned, 0, 6>(i, 1)));
         assert((static_cast<unsigned>(wd)   == euclidian_addition<unsigned, 0, 6>(i, 2)));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ok.pass.cpp
index f8bd9d43a25..f2f6e2e9802 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday = std::chrono::weekday;
 
@@ -34,4 +34,6 @@ int main()
         assert(weekday{i}.ok());
     for (unsigned i = 7; i <= 255; ++i)
         assert(!weekday{i}.ok());
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/operator[].pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/operator[].pass.cpp
index aa0f3f7e59e..d7d2d6faf30 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/operator[].pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/operator[].pass.cpp
@@ -21,7 +21,7 @@
 #include "test_macros.h"
 #include "../../euclidian.h"
 
-int main()
+int main(int, char**)
 {
     using weekday         = std::chrono::weekday;
     using weekday_last    = std::chrono::weekday_last;
@@ -55,4 +55,6 @@ int main()
         assert(wdi.index() == j);
         assert(wdi.ok());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/plus_minus_equal.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/plus_minus_equal.pass.cpp
index e0963540cf2..d99b0349399 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/plus_minus_equal.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.members/plus_minus_equal.pass.cpp
@@ -33,7 +33,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using weekday = std::chrono::weekday;
     using days    = std::chrono::days;
@@ -59,4 +59,6 @@ int main()
         assert((static_cast<unsigned>(wd -= days{4}) == euclidian_subtraction<unsigned, 0, 6>(i, 4)));
         assert((static_cast<unsigned>(wd)            == euclidian_subtraction<unsigned, 0, 6>(i, 4)));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/comparisons.pass.cpp
index c042ac14778..982b3bccbc6 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/comparisons.pass.cpp
@@ -21,7 +21,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using weekday = std::chrono::weekday;
 
@@ -38,4 +38,6 @@ int main()
     for (unsigned i = 0; i < 6; ++i)
         for (unsigned j = 0; j < 6; ++j)
             assert(testComparisons2Values<weekday>(i, j));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/literals.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/literals.pass.cpp
index 8f713aad280..7529864a5bb 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/literals.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/literals.pass.cpp
@@ -24,7 +24,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 
     ASSERT_SAME_TYPE(const std::chrono::weekday, decltype(std::chrono::Sunday));
@@ -58,4 +58,6 @@ int main()
     assert(static_cast<unsigned>(std::chrono::Thursday)  ==  4);
     assert(static_cast<unsigned>(std::chrono::Friday)    ==  5);
     assert(static_cast<unsigned>(std::chrono::Saturday)  ==  6);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/minus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/minus.pass.cpp
index 2bf0ed78995..f296fc6d68e 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/minus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/minus.pass.cpp
@@ -44,7 +44,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using weekday  = std::chrono::weekday;
     using days     = std::chrono::days;
@@ -72,4 +72,6 @@ int main()
             assert(weekday{i} + d == weekday{j});
         }
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/plus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/plus.pass.cpp
index 287834cd7e8..78d332b96cb 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/plus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/plus.pass.cpp
@@ -44,7 +44,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using weekday = std::chrono::weekday;
     using days    = std::chrono::days;
@@ -66,4 +66,6 @@ int main()
             assert((static_cast<unsigned>(wd1) == euclidian_addition<unsigned, 0, 6>(i, j)));
             assert((static_cast<unsigned>(wd2) == euclidian_addition<unsigned, 0, 6>(i, j)));
         }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/streaming.pass.cpp
index aef5a82e78d..43825b60e99 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/time.cal.weekday.nonmembers/streaming.pass.cpp
@@ -47,9 +47,11 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
    using weekday = std::chrono::weekday;
 
    std::cout << weekday{3};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/types.pass.cpp
index ed355b02515..7264a210f59 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.weekday/types.pass.cpp
@@ -16,10 +16,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using weekday = std::chrono::weekday;
 
     static_assert(std::is_trivially_copyable_v<weekday>, "");
     static_assert(std::is_standard_layout_v<weekday>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/ctor.pass.cpp
index 5f8b4660a24..e46b5563064 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/ctor.pass.cpp
@@ -23,7 +23,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year = std::chrono::year;
 
@@ -42,4 +42,6 @@ int main()
         year year(i);
         assert(static_cast<int>(year) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/decrement.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/decrement.pass.cpp
index e8473bf9810..893c48aab47 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/decrement.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/decrement.pass.cpp
@@ -30,7 +30,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year = std::chrono::year;
     ASSERT_NOEXCEPT(--(std::declval<year&>())  );
@@ -48,4 +48,6 @@ int main()
         assert(static_cast<int>(year--) == i - 1);
         assert(static_cast<int>(year)   == i - 2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/increment.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/increment.pass.cpp
index 759fb66617b..ef2a6f3fbee 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/increment.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/increment.pass.cpp
@@ -30,7 +30,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year = std::chrono::year;
     ASSERT_NOEXCEPT(++(std::declval<year&>())  );
@@ -48,4 +48,6 @@ int main()
         assert(static_cast<int>(year++) == i + 1);
         assert(static_cast<int>(year)   == i + 2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/is_leap.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/is_leap.pass.cpp
index b1785b86c59..37031dbbabc 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/is_leap.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/is_leap.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year = std::chrono::year;
 
@@ -49,4 +49,6 @@ int main()
     assert(!year{ 2003}.is_leap());
     assert( year{ 2004}.is_leap());
     assert(!year{ 2100}.is_leap());
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/ok.pass.cpp
index dfc2ad3ffe4..f56ee34d598 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/ok.pass.cpp
@@ -24,7 +24,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year = std::chrono::year;
 
@@ -49,4 +49,6 @@ int main()
     assert(year{ 20001}.ok());
 
     static_assert(!year{-32768}.ok(), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/plus_minus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/plus_minus.pass.cpp
index 65b1494587b..0adb0f9fe58 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/plus_minus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/plus_minus.pass.cpp
@@ -28,7 +28,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year  = std::chrono::year;
 
@@ -46,4 +46,6 @@ int main()
         assert(static_cast<int>(+year) ==  i);
         assert(static_cast<int>(-year) == -i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/plus_minus_equal.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/plus_minus_equal.pass.cpp
index a00a36f2dca..b79713ed1c8 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/plus_minus_equal.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.members/plus_minus_equal.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year  = std::chrono::year;
     using years = std::chrono::years;
@@ -53,4 +53,6 @@ int main()
         assert(static_cast<int>(year -= years{ 9}) == i +  1);
         assert(static_cast<int>(year)              == i +  1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/comparisons.pass.cpp
index 8d675f4db39..9e84fe36ee0 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/comparisons.pass.cpp
@@ -26,7 +26,7 @@
 #include "test_comparisons.h"
 
 
-int main()
+int main(int, char**)
 {
     using year = std::chrono::year;
 
@@ -43,4 +43,6 @@ int main()
     for (int i = 1; i < 10; ++i)
         for (int j = 1; j < 10; ++j)
             assert(testComparisons6Values<year>(i, j));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/literals.fail.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/literals.fail.cpp
index c6138c7af1c..50c7b7bc0a6 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/literals.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/literals.fail.cpp
@@ -20,8 +20,10 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using std::chrono::year;
     year d1 = 1234y; // expected-error-re {{no matching literal operator for call to 'operator""y' {{.*}}}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/literals.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/literals.pass.cpp
index 6ebd0e66fdd..a2bec73e696 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/literals.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/literals.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     using namespace std::chrono;
@@ -40,4 +40,6 @@ int main()
     std::chrono::year y1 = 2020y;
     assert (y1 == std::chrono::year(2020));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/minus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/minus.pass.cpp
index 3e3e0b77db4..f112345c0ad 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/minus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/minus.pass.cpp
@@ -37,7 +37,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year  = std::chrono::year;
     using years = std::chrono::years;
@@ -58,4 +58,6 @@ int main()
         assert(static_cast<int>(y1) == 1223 - i);
         assert(ys1.count()          == 1223 - i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/plus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/plus.pass.cpp
index 15c713defb4..d73f6fc88b3 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/plus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/plus.pass.cpp
@@ -33,7 +33,7 @@ constexpr bool testConstexpr()
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year  = std::chrono::year;
     using years = std::chrono::years;
@@ -55,4 +55,6 @@ int main()
         assert(static_cast<int>(y1) == i + 1223);
         assert(static_cast<int>(y2) == i + 1223);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/streaming.pass.cpp
index 2c52cde0a43..1b278f2b903 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/time.cal.year.nonmembers/streaming.pass.cpp
@@ -46,9 +46,11 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
    using year = std::chrono::year;
 
    std::cout << year{2018};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.year/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.year/types.pass.cpp
index 10bea23a035..2acb0f104d3 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.year/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.year/types.pass.cpp
@@ -16,10 +16,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year = std::chrono::year;
 
     static_assert(std::is_trivially_copyable_v<year>, "");
     static_assert(std::is_standard_layout_v<year>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/ctor.pass.cpp
index 090a1ac212c..1c05cf7a6b6 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/ctor.pass.cpp
@@ -25,7 +25,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year       = std::chrono::year;
     using month      = std::chrono::month;
@@ -48,4 +48,6 @@ int main()
     static_assert( ym2.year()  == year{2018}, "");
     static_assert( ym2.month() == month{},    "");
     static_assert(!ym2.ok(),                  "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/month.pass.cpp
index 97334b20503..7e0cd17f467 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/month.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year       = std::chrono::year;
     using month      = std::chrono::month;
@@ -35,4 +35,6 @@ int main()
         year_month ym(year{1234}, month{i});
         assert( static_cast<unsigned>(ym.month()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/ok.pass.cpp
index 54e67dff9a3..463289ee43f 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using month      = std::chrono::month;
     using year       = std::chrono::year;
@@ -46,4 +46,6 @@ int main()
         year_month ym{year{i}, January};
         assert( ym.ok() == year{i}.ok());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/plus_minus_equal_month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/plus_minus_equal_month.pass.cpp
index 76f3b3355d2..a403462ff79 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/plus_minus_equal_month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/plus_minus_equal_month.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr(D d1)
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using month      = std::chrono::month;
     using months     = std::chrono::months;
@@ -60,4 +60,6 @@ int main()
         assert(static_cast<unsigned>((ym             ).month()) == i + 1);
         assert(ym.year() == y);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/plus_minus_equal_year.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/plus_minus_equal_year.pass.cpp
index 05cd60844d9..adf08fc24b8 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/plus_minus_equal_year.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/plus_minus_equal_year.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr(D d1)
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using month      = std::chrono::month;
     using year       = std::chrono::year;
@@ -61,4 +61,6 @@ int main()
         assert(static_cast<int>((ym            ).year()) == i + 1);
         assert(ym.month() == m);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/year.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/year.pass.cpp
index e8476b04280..024f3140425 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/year.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.members/year.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year       = std::chrono::year;
     using month      = std::chrono::month;
@@ -35,4 +35,6 @@ int main()
         year_month ym(year{i}, month{});
         assert( static_cast<int>(ym.year()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/comparisons.pass.cpp
index e1ab033c7c7..d102b0a5620 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/comparisons.pass.cpp
@@ -26,7 +26,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using year       = std::chrono::year;
     using month      = std::chrono::month;
@@ -65,4 +65,6 @@ int main()
             year_month{year{i}, std::chrono::January},
             year_month{year{j}, std::chrono::January},
             i == j, i < j )));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/minus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/minus.pass.cpp
index 2999560f16f..d7756d10d25 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/minus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/minus.pass.cpp
@@ -29,7 +29,7 @@
 
 #include <iostream>
 
-int main()
+int main(int, char**)
 {
     using year       = std::chrono::year;
     using years      = std::chrono::years;
@@ -86,4 +86,6 @@ int main()
 //  TODO: different year
 
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/plus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/plus.pass.cpp
index dc721adeedb..5698e724470 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/plus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/plus.pass.cpp
@@ -51,7 +51,7 @@ constexpr bool testConstexprMonths(std::chrono::year_month ym)
 }
 
 
-int main()
+int main(int, char**)
 {
     using year       = std::chrono::year;
     using years      = std::chrono::years;
@@ -102,4 +102,6 @@ int main()
         assert(ym1 == ym2);
     }
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/streaming.pass.cpp
index e75fc21bf88..43af6c2f719 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/time.cal.ym.nonmembers/streaming.pass.cpp
@@ -46,11 +46,13 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year_month = std::chrono::year_month;
     using year       = std::chrono::year;
     using month      = std::chrono::month;
 
     std::cout << year_month{year{2018}, month{3}};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/types.pass.cpp
index a3b9999f8fd..2e88c6bb6b6 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ym/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ym/types.pass.cpp
@@ -16,10 +16,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year_month = std::chrono::year_month;
 
     static_assert(std::is_trivially_copyable_v<year_month>, "");
     static_assert(std::is_standard_layout_v<year_month>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.local_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.local_days.pass.cpp
index 9cebaa6836a..274cb6a266f 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.local_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.local_days.pass.cpp
@@ -29,7 +29,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using day            = std::chrono::day;
@@ -81,4 +81,6 @@ int main()
     assert( ymd.month() == std::chrono::November);
     assert( ymd.day()   == day{29});
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.pass.cpp
index a5818849add..fdef9517e4a 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.pass.cpp
@@ -28,7 +28,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using month          = std::chrono::month;
@@ -52,4 +52,6 @@ int main()
     static_assert( ym1.day()   == day{12},    "");
     static_assert( ym1.ok(),                  "");
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.sys_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.sys_days.pass.cpp
index 7344c10c1ad..433468477d5 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.sys_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.sys_days.pass.cpp
@@ -28,7 +28,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using day            = std::chrono::day;
@@ -80,4 +80,6 @@ int main()
     assert( ymd.month() == std::chrono::November);
     assert( ymd.day()   == day{29});
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.year_month_day_last.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.year_month_day_last.pass.cpp
index 913b403952b..d4e8fc83d5b 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.year_month_day_last.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ctor.year_month_day_last.pass.cpp
@@ -26,7 +26,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month               = std::chrono::month;
@@ -76,4 +76,6 @@ int main()
     assert( ymd.day()   == day{28});
     assert( ymd.ok());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/day.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/day.pass.cpp
index 12e1515b171..9a068737ddc 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/day.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/day.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using month          = std::chrono::month;
@@ -36,4 +36,6 @@ int main()
         year_month_day ymd(year{1234}, month{2}, day{i});
         assert( static_cast<unsigned>(ymd.day()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/month.pass.cpp
index 8c091d05165..f1dd2e6893a 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/month.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using month          = std::chrono::month;
@@ -36,4 +36,6 @@ int main()
         year_month_day ymd(year{1234}, month{i}, day{12});
         assert( static_cast<unsigned>(ymd.month()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ok.pass.cpp
index edb55f58b4c..cab639b820a 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using month          = std::chrono::month;
@@ -92,4 +92,6 @@ int main()
         year_month_day ym{year{i}, January, day{12}};
         assert( ym.ok() == year{i}.ok());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/op.local_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/op.local_days.pass.cpp
index 02212dc9094..038d21c4670 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/op.local_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/op.local_days.pass.cpp
@@ -44,7 +44,7 @@ void RunTheExample()
     static_assert(year_month_day{local_days{year{2017}/January/32}} == year{2017}/February/1);  
 }
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using month          = std::chrono::month;
@@ -90,4 +90,5 @@ int main()
     assert( year_month_day{sd} == ymd); // and back
     }
 
+    return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/op.sys_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/op.sys_days.pass.cpp
index 5925cb0cb5c..a9568455085 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/op.sys_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/op.sys_days.pass.cpp
@@ -44,7 +44,7 @@ void RunTheExample()
     static_assert(year_month_day{sys_days{year{2017}/January/32}} == year{2017}/February/1);  
 }
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using month          = std::chrono::month;
@@ -90,4 +90,5 @@ int main()
     assert( year_month_day{sd} == ymd); // and back
     }
 
+    return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/plus_minus_equal_month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/plus_minus_equal_month.pass.cpp
index 173b8b6a2fb..8530248d1d6 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/plus_minus_equal_month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/plus_minus_equal_month.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr(D d1)
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using month          = std::chrono::month;
@@ -66,4 +66,6 @@ int main()
         assert(ym.year() == y);
         assert(ym.day()  == d);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/plus_minus_equal_year.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/plus_minus_equal_year.pass.cpp
index 1d995129152..ae134d1a240 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/plus_minus_equal_year.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/plus_minus_equal_year.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr(D d1)
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using month          = std::chrono::month;
@@ -66,4 +66,6 @@ int main()
         assert(ym.month() == m);
         assert(ym.day()   == d);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/year.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/year.pass.cpp
index 465fa9d93db..fc5a4072493 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/year.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.members/year.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using month          = std::chrono::month;
@@ -36,4 +36,6 @@ int main()
         year_month_day ym(year{i}, month{}, day{});
         assert( static_cast<int>(ym.year()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/comparisons.pass.cpp
index 8d5bf89553c..0d15589252a 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/comparisons.pass.cpp
@@ -29,7 +29,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using day        = std::chrono::day;
     using year       = std::chrono::year;
@@ -114,4 +114,6 @@ int main()
             year_month_day{year{i}, January, day{12}},
             year_month_day{year{j}, January, day{12}},
             i == j, i < j )));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/minus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/minus.pass.cpp
index 4d5625ba739..3c921def3b8 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/minus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/minus.pass.cpp
@@ -33,7 +33,7 @@ constexpr bool test_constexpr ()
         ;
 }
 
-int main()
+int main(int, char**)
 {
     using year           = std::chrono::year;
     using month          = std::chrono::month;
@@ -56,4 +56,6 @@ int main()
         assert(ym1.month() == January);
         assert(ym1.day() == day{10});
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/plus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/plus.pass.cpp
index 2913eb23743..8d5e02543aa 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/plus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/plus.pass.cpp
@@ -51,7 +51,7 @@ constexpr bool testConstexprMonths(std::chrono::year_month_day ym)
 }
 
 
-int main()
+int main(int, char**)
 {
     using day        = std::chrono::day;
     using year       = std::chrono::year;
@@ -108,4 +108,6 @@ int main()
     }
     }
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/streaming.pass.cpp
index cce42bc616d..47b6f02490d 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/time.cal.ymd.nonmembers/streaming.pass.cpp
@@ -46,7 +46,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year_month_day = std::chrono::year_month_day;
     using year           = std::chrono::year;
@@ -54,4 +54,6 @@ int main()
     using day            = std::chrono::day;
 
     std::cout << year_month_day{year{2018}, month{3}, day{12}};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/types.pass.cpp
index c61d1c9960f..58acd143df9 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymd/types.pass.cpp
@@ -16,10 +16,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year_month_day = std::chrono::year_month_day;
 
     static_assert(std::is_trivially_copyable_v<year_month_day>, "");
     static_assert(std::is_standard_layout_v<year_month_day>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/ctor.pass.cpp
index d27c3c67e5e..bd4729f6a0e 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/ctor.pass.cpp
@@ -27,7 +27,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month               = std::chrono::month;
@@ -49,4 +49,6 @@ int main()
     static_assert( ymdl1.month()          == January,                 "");
     static_assert( ymdl1.month_day_last() == month_day_last{January}, "");
     static_assert( ymdl1.ok(),                                        "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/day.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/day.pass.cpp
index 24682b6957f..2f0e2ba17a7 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/day.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/day.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month               = std::chrono::month;
@@ -47,4 +47,6 @@ int main()
     assert((year_month_day_last{year{2019}, month_day_last{month{ 2}}}.day() == day{28}));
     assert((year_month_day_last{year{2020}, month_day_last{month{ 2}}}.day() == day{29}));
     assert((year_month_day_last{year{2021}, month_day_last{month{ 2}}}.day() == day{28}));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/month.pass.cpp
index cf1024a8ce3..5b68aa1d95c 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/month.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month               = std::chrono::month;
@@ -34,4 +34,6 @@ int main()
         year_month_day_last ymd(year{1234}, month_day_last{month{i}});
         assert( static_cast<unsigned>(ymd.month()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/month_day_last.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/month_day_last.pass.cpp
index 5c99d947124..cca9026b650 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/month_day_last.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/month_day_last.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month               = std::chrono::month;
@@ -34,4 +34,6 @@ int main()
         year_month_day_last ymdl(year{1234}, month_day_last{month{i}});
         assert( static_cast<unsigned>(ymdl.month_day_last().month()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/ok.pass.cpp
index bb4c410d449..d40de103c2a 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month               = std::chrono::month;
@@ -48,4 +48,6 @@ int main()
         year_month_day_last ym{year{i}, month_day_last{January}};
         assert( ym.ok() == year{i}.ok());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/op_local_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/op_local_days.pass.cpp
index 83f8b70dc79..a96dff338be 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/op_local_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/op_local_days.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month_day_last      = std::chrono::month_day_last;
@@ -57,4 +57,6 @@ int main()
 
     assert(sd.time_since_epoch() == days{-(10957+33)});
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/op_sys_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/op_sys_days.pass.cpp
index 9a32112c901..250ca0f1123 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/op_sys_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/op_sys_days.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month_day_last      = std::chrono::month_day_last;
@@ -57,4 +57,6 @@ int main()
 
     assert(sd.time_since_epoch() == days{-(10957+33)});
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/plus_minus_equal_month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/plus_minus_equal_month.pass.cpp
index 2c4d1ff1f17..7091f64ea33 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/plus_minus_equal_month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/plus_minus_equal_month.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr(D d1)
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month               = std::chrono::month;
@@ -62,4 +62,6 @@ int main()
         assert(static_cast<unsigned>((ym             ).month()) == i + 1);
         assert(ym.year() == y);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/plus_minus_equal_year.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/plus_minus_equal_year.pass.cpp
index 00335e15d54..3c1ad352737 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/plus_minus_equal_year.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/plus_minus_equal_year.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr(D d1)
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month               = std::chrono::month;
@@ -61,4 +61,6 @@ int main()
         assert(static_cast<int>((ymdl            ).year()) == i + 1);
         assert(ymdl.month_day_last() == mdl);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/year.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/year.pass.cpp
index 49387091d76..c0db150f96d 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/year.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.members/year.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month               = std::chrono::month;
@@ -34,4 +34,6 @@ int main()
         year_month_day_last ym(year{i}, month_day_last{month{}});
         assert( static_cast<int>(ym.year()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/comparisons.pass.cpp
index 9db4b6aa6d9..c56491f96cb 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/comparisons.pass.cpp
@@ -26,7 +26,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month               = std::chrono::month;
@@ -83,4 +83,6 @@ int main()
             year_month_day_last{year{i}, month_day_last{January}},
             year_month_day_last{year{j}, month_day_last{January}},
             i == j, i < j )));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/minus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/minus.pass.cpp
index 7f5a796dfab..8ea3025d607 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/minus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/minus.pass.cpp
@@ -47,7 +47,7 @@ constexpr bool testConstexprMonths (std::chrono::year_month_day_last ymdl)
         ;
 }
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month               = std::chrono::month;
@@ -87,4 +87,6 @@ int main()
     }
     }
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/plus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/plus.pass.cpp
index c494620df6e..75cabbdcd28 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/plus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/plus.pass.cpp
@@ -63,7 +63,7 @@ constexpr bool testConstexprMonths(std::chrono::year_month_day_last ymdl)
 }
 
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month               = std::chrono::month;
@@ -118,4 +118,6 @@ int main()
     }
     }
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/streaming.pass.cpp
index 268eb88fe17..eca8d3d6851 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymdlast/time.cal.ymdlast.nonmembers/streaming.pass.cpp
@@ -25,7 +25,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year_month_day_last = std::chrono::year_month_day_last;
     using year                = std::chrono::year;
@@ -33,4 +33,6 @@ int main()
     using month_day_last      = std::chrono::month_day_last;
 
     std::cout << year_month_day_last{year{2018}, month_day_last{month{3}}};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ctor.local_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ctor.local_days.pass.cpp
index 0eae24e459c..bb4e7d04405 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ctor.local_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ctor.local_days.pass.cpp
@@ -29,7 +29,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using days               = std::chrono::days;
@@ -91,4 +91,6 @@ int main()
     assert((ymwd.weekday_indexed() == weekday_indexed{std::chrono::Wednesday, 5}));
     assert( ymwd                   == year_month_weekday{local_days{ymwd}}); // round trip
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ctor.pass.cpp
index dab8b21577b..81030ff559d 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ctor.pass.cpp
@@ -30,7 +30,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -60,4 +60,6 @@ int main()
     static_assert( ym1.weekday_indexed() == weekday_indexed{Tuesday, 1}, "");
     static_assert( ym1.ok(),                                             "");
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ctor.sys_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ctor.sys_days.pass.cpp
index 96261c54e3c..5ae9900a983 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ctor.sys_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ctor.sys_days.pass.cpp
@@ -28,7 +28,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using days               = std::chrono::days;
@@ -90,4 +90,6 @@ int main()
     assert((ymwd.weekday_indexed() == weekday_indexed{std::chrono::Wednesday, 5}));
     assert( ymwd                   == year_month_weekday{sys_days{ymwd}}); // round trip
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/index.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/index.pass.cpp
index 4c0bc13c186..ecbd8aec830 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/index.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/index.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -37,4 +37,6 @@ int main()
         year_month_weekday ymwd0(year{1234}, month{2}, weekday_indexed{weekday{2}, i});
         assert(ymwd0.index() == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/month.pass.cpp
index 0e2d41a771f..c300fd5d36a 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/month.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -36,4 +36,6 @@ int main()
         year_month_weekday ymd(year{1234}, month{i}, weekday_indexed{});
         assert( static_cast<unsigned>(ymd.month()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ok.pass.cpp
index f66d6a083c4..7e8599e0509 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -71,4 +71,6 @@ int main()
         year_month_weekday ym{year{i}, January, weekday_indexed{Tuesday, 1}};
         assert((ym.ok() == year{i}.ok()));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/op.local_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/op.local_days.pass.cpp
index 788af653555..e86e5b0fa6e 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/op.local_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/op.local_days.pass.cpp
@@ -25,7 +25,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -70,4 +70,5 @@ int main()
     assert( year_month_weekday{sd} == ymwd); // and back
     }
 
+    return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/op.sys_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/op.sys_days.pass.cpp
index 111cf5f38db..afb1d70148a 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/op.sys_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/op.sys_days.pass.cpp
@@ -25,7 +25,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -70,4 +70,5 @@ int main()
     assert( year_month_weekday{sd} == ymwd); // and back
     }
 
+    return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/plus_minus_equal_month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/plus_minus_equal_month.pass.cpp
index 7e20a8eb05a..fd53279ddde 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/plus_minus_equal_month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/plus_minus_equal_month.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr(D d1)
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -76,4 +76,6 @@ int main()
         assert(ymwd.weekday()  == Tuesday);
         assert(ymwd.index()    == 2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/plus_minus_equal_year.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/plus_minus_equal_year.pass.cpp
index 4deee9bc35d..cf229febe08 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/plus_minus_equal_year.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/plus_minus_equal_year.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr(D d1)
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -76,4 +76,6 @@ int main()
         assert(ymwd.weekday()  == Tuesday);
         assert(ymwd.index()    == 2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/weekday.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/weekday.pass.cpp
index 1b9c8ad1041..dac1f7cc049 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/weekday.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/weekday.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -37,4 +37,6 @@ int main()
         year_month_weekday ymwd0(year{1234}, month{2}, weekday_indexed{weekday{i}, 1});
         assert(static_cast<unsigned>(ymwd0.weekday()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/weekday_indexed.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/weekday_indexed.pass.cpp
index 4a9832323f1..f089a8cb93e 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/weekday_indexed.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/weekday_indexed.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -41,4 +41,6 @@ int main()
         assert( static_cast<unsigned>(ymwd1.weekday_indexed().weekday()) == 2);
         assert( static_cast<unsigned>(ymwd1.weekday_indexed().index()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/year.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/year.pass.cpp
index 8103c28aa60..1ead67570cf 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/year.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.members/year.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -36,4 +36,6 @@ int main()
         year_month_weekday ym(year{i}, month{1}, weekday_indexed{});
         assert( static_cast<int>(ym.year()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/comparisons.pass.cpp
index 847699b2516..5631127222b 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/comparisons.pass.cpp
@@ -22,7 +22,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -109,4 +109,6 @@ int main()
             year_month_weekday{year{i}, January, weekday_indexed{Tuesday, 1}},
             year_month_weekday{year{j}, January, weekday_indexed{Tuesday, 1}},
             i == j)));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/minus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/minus.pass.cpp
index ff472fdc6ce..47cfbea6a67 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/minus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/minus.pass.cpp
@@ -50,7 +50,7 @@ constexpr bool testConstexprMonths ()
 }
 
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -96,4 +96,6 @@ int main()
         assert(ym1.index()   == 2);
     }
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/plus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/plus.pass.cpp
index bc72d958ca0..29df4776e2b 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/plus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/plus.pass.cpp
@@ -51,7 +51,7 @@ constexpr bool testConstexprMonths(std::chrono::year_month_weekday ym)
 }
 
 
-int main()
+int main(int, char**)
 {
     using year               = std::chrono::year;
     using month              = std::chrono::month;
@@ -116,4 +116,6 @@ int main()
     }
     }
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/streaming.pass.cpp
index eb92cf05e47..411e4335fd0 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/time.cal.ymwd.nonmembers/streaming.pass.cpp
@@ -45,7 +45,7 @@
 #include <iostream>
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year_month_weekday = std::chrono::year_month_weekday;
     using year                = std::chrono::year;
@@ -53,4 +53,6 @@ int main()
     using weekday             = std::chrono::weekday;
 
     std::cout << year_month_weekday{year{2018}, month{3}, weekday{4}};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/types.pass.cpp
index 449098c4f18..76e2e0f237e 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwd/types.pass.cpp
@@ -16,10 +16,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year_month_weekday = std::chrono::year_month_weekday;
 
     static_assert(std::is_trivially_copyable_v<year_month_weekday>, "");
     static_assert(std::is_standard_layout_v<year_month_weekday>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/ctor.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/ctor.pass.cpp
index 1db6850dbce..31d2e9ca706 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/ctor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/ctor.pass.cpp
@@ -28,7 +28,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                    = std::chrono::year;
     using month                   = std::chrono::month;
@@ -48,4 +48,6 @@ int main()
     static_assert( ym1.weekday_last() == weekday_last{Tuesday}, "");
     static_assert( ym1.ok(),                                    "");
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/month.pass.cpp
index 7b95084b214..df62d010ab6 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/month.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                    = std::chrono::year;
     using month                   = std::chrono::month;
@@ -37,4 +37,6 @@ int main()
         year_month_weekday_last ymd(year{1234}, month{i}, weekday_last{weekday{}});
         assert( static_cast<unsigned>(ymd.month()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/ok.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/ok.pass.cpp
index 1cffb4565b7..c18b926704c 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/ok.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/ok.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                    = std::chrono::year;
     using month                   = std::chrono::month;
@@ -69,4 +69,6 @@ int main()
         year_month_weekday_last ym{year{i}, January, weekday_last{Tuesday}};
         assert((ym.ok() == year{i}.ok()));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/op_local_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/op_local_days.pass.cpp
index 83f8b70dc79..c663406ee43 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/op_local_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/op_local_days.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                = std::chrono::year;
     using month_day_last      = std::chrono::month_day_last;
@@ -57,4 +57,6 @@ int main()
 
     assert(sd.time_since_epoch() == days{-(10957+33)});
     }
+
+    return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/op_sys_days.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/op_sys_days.pass.cpp
index cc3da2992e8..cb75842c64c 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/op_sys_days.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/op_sys_days.pass.cpp
@@ -22,7 +22,7 @@
 
 #include <iostream>
 
-int main()
+int main(int, char**)
 {
     using year                    = std::chrono::year;
     using month                   = std::chrono::month;
@@ -65,4 +65,6 @@ int main()
 
     assert(sd.time_since_epoch() == days{-(10957+35)});
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/plus_minus_equal_month.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/plus_minus_equal_month.pass.cpp
index ad513c5d0cf..b2bb1361b6b 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/plus_minus_equal_month.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/plus_minus_equal_month.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr(D d1)
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year                    = std::chrono::year;
     using month                   = std::chrono::month;
@@ -71,4 +71,6 @@ int main()
         assert(ymwd.year()     == y);
         assert(ymwd.weekday()  == Tuesday);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/plus_minus_equal_year.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/plus_minus_equal_year.pass.cpp
index 7d9255fe494..8ced182d6c8 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/plus_minus_equal_year.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/plus_minus_equal_year.pass.cpp
@@ -32,7 +32,7 @@ constexpr bool testConstexpr(D d1)
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year                    = std::chrono::year;
     using month                   = std::chrono::month;
@@ -72,4 +72,6 @@ int main()
         assert(ymwd.month()    == January);
         assert(ymwd.weekday()  == Tuesday);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/weekday.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/weekday.pass.cpp
index cc0521354f9..1de0b832309 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/weekday.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/weekday.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                    = std::chrono::year;
     using month                   = std::chrono::month;
@@ -37,4 +37,6 @@ int main()
         year_month_weekday_last ymwdl(year{1}, month{1}, weekday_last{weekday{i}});
         assert(static_cast<unsigned>(ymwdl.weekday()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/year.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/year.pass.cpp
index 4011f0673ff..4e940791145 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/year.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.members/year.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year                    = std::chrono::year;
     using month                   = std::chrono::month;
@@ -37,4 +37,6 @@ int main()
         year_month_weekday_last ymwdl(year{i}, month{1}, weekday_last{weekday{}});
         assert(static_cast<int>(ymwdl.year()) == i);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/comparisons.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/comparisons.pass.cpp
index a13b11f8c10..24074f33cbc 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/comparisons.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/comparisons.pass.cpp
@@ -22,7 +22,7 @@
 #include "test_macros.h"
 #include "test_comparisons.h"
 
-int main()
+int main(int, char**)
 {
     using year                    = std::chrono::year;
     using month                   = std::chrono::month;
@@ -110,4 +110,6 @@ int main()
             year_month_weekday_last{year{i}, January, weekday_last{Tuesday}},
             year_month_weekday_last{year{j}, January, weekday_last{Tuesday}},
             i == j)));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/minus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/minus.pass.cpp
index 20a58152f33..d58c461be8b 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/minus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/minus.pass.cpp
@@ -40,7 +40,7 @@ constexpr bool testConstexprMonths(std::chrono::year_month_weekday_last ym)
     return true;
 }
 
-int main()
+int main(int, char**)
 {
     using year                    = std::chrono::year;
     using month                   = std::chrono::month;
@@ -89,4 +89,6 @@ int main()
     }
     }
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/plus.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/plus.pass.cpp
index 45dd7562dc0..fe246cf42ba 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/plus.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/plus.pass.cpp
@@ -47,7 +47,7 @@ constexpr bool testConstexprMonths(std::chrono::year_month_weekday_last ym)
 }
 
 
-int main()
+int main(int, char**)
 {
     using year                    = std::chrono::year;
     using month                   = std::chrono::month;
@@ -112,4 +112,6 @@ int main()
     }
     }
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/streaming.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/streaming.pass.cpp
index 6e4409c7138..cdfe55f1650 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/streaming.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/time.cal.ymwdlast.nonmembers/streaming.pass.cpp
@@ -25,7 +25,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year_month_weekday_last = std::chrono::year_month_weekday_last;
     using year                    = std::chrono::year;
@@ -34,4 +34,6 @@ int main()
     using weekday_last            = std::chrono::weekday_last;
 
     std::cout << year_month_weekday_last{year{2018}, month{3}, weekday_last{weekday{4}}};
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/types.pass.cpp b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/types.pass.cpp
index e0580fac76f..70dea7bf922 100644
--- a/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.cal/time.cal.ymwdlast/types.pass.cpp
@@ -16,10 +16,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using year_month_weekday_last = std::chrono::year_month_weekday_last;
 
     static_assert(std::is_trivially_copyable_v<year_month_weekday_last>, "");
     static_assert(std::is_standard_layout_v<year_month_weekday_last>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock.req/nothing_to_do.pass.cpp b/libcxx/test/std/utilities/time/time.clock.req/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/utilities/time/time.clock.req/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock.req/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/nothing_to_do.pass.cpp b/libcxx/test/std/utilities/time/time.clock/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/utilities/time/time.clock/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.file/consistency.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.file/consistency.pass.cpp
index 332d8163cb6..165bec2e117 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.file/consistency.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.file/consistency.pass.cpp
@@ -22,7 +22,7 @@
 template <class T>
 void test(const T &) {}
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::file_clock C;
     static_assert((std::is_same<C::rep, C::duration::rep>::value), "");
@@ -31,4 +31,6 @@ int main()
     static_assert((std::is_same<C::time_point::clock, C>::value), "");
     static_assert(!C::is_steady, "");
     test(std::chrono::file_clock::is_steady);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.file/file_time.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.file/file_time.pass.cpp
index 75652f3ecd0..61d92381fc8 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.file/file_time.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.file/file_time.pass.cpp
@@ -21,8 +21,10 @@ void test() {
   ASSERT_SAME_TYPE(std::chrono::file_time<Dur>, std::chrono::time_point<std::chrono::file_clock, Dur>);
 }
 
-int main() {
+int main(int, char**) {
   test<std::chrono::nanoseconds>();
   test<std::chrono::minutes>();
   test<std::chrono::hours>();
+
+  return 0;
 }
\ No newline at end of file
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.file/now.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.file/now.pass.cpp
index 3b51b91b501..79cdf06120c 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.file/now.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.file/now.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::file_clock C;
     ASSERT_NOEXCEPT(C::now());
@@ -31,4 +31,6 @@ int main()
     assert(t1.time_since_epoch().count() != 0);
     assert(C::time_point::min() < t1);
     assert(C::time_point::max() > t1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.file/rep_signed.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.file/rep_signed.pass.cpp
index c36649a5d41..821072e6df6 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.file/rep_signed.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.file/rep_signed.pass.cpp
@@ -20,9 +20,11 @@
 #include <chrono>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     static_assert(std::is_signed<std::chrono::file_clock::rep>::value, "");
     assert(std::chrono::file_clock::duration::min() <
            std::chrono::file_clock::duration::zero());
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.hires/consistency.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.hires/consistency.pass.cpp
index 6f06e718e25..1650d3b6b5f 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.hires/consistency.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.hires/consistency.pass.cpp
@@ -27,7 +27,7 @@
 template <class T>
 void test(const T &) {}
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::high_resolution_clock C;
     static_assert((std::is_same<C::rep, C::duration::rep>::value), "");
@@ -35,4 +35,6 @@ int main()
     static_assert((std::is_same<C::duration, C::time_point::duration>::value), "");
     static_assert(C::is_steady || !C::is_steady, "");
     test(std::chrono::high_resolution_clock::is_steady);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.hires/now.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.hires/now.pass.cpp
index c1d879c6f3b..ddf3ced87da 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.hires/now.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.hires/now.pass.cpp
@@ -15,11 +15,13 @@
 #include <chrono>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::high_resolution_clock C;
     C::time_point t1 = C::now();
     assert(t1.time_since_epoch().count() != 0);
     assert(C::time_point::min() < t1);
     assert(C::time_point::max() > t1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.steady/consistency.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.steady/consistency.pass.cpp
index 1577bc18008..0797f2cb5bc 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.steady/consistency.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.steady/consistency.pass.cpp
@@ -29,7 +29,7 @@
 template <class T>
 void test(const T &) {}
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::steady_clock C;
     static_assert((std::is_same<C::rep, C::duration::rep>::value), "");
@@ -37,4 +37,6 @@ int main()
     static_assert((std::is_same<C::duration, C::time_point::duration>::value), "");
     static_assert(C::is_steady, "");
     test(std::chrono::steady_clock::is_steady);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.steady/now.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.steady/now.pass.cpp
index 248f1523f87..7d268fd67de 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.steady/now.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.steady/now.pass.cpp
@@ -17,10 +17,12 @@
 #include <chrono>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::steady_clock C;
     C::time_point t1 = C::now();
     C::time_point t2 = C::now();
     assert(t2 >= t1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.system/consistency.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.system/consistency.pass.cpp
index b15a8e2124d..b92652134ad 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.system/consistency.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.system/consistency.pass.cpp
@@ -27,7 +27,7 @@
 template <class T>
 void test(const T &) {}
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock C;
     static_assert((std::is_same<C::rep, C::duration::rep>::value), "");
@@ -36,4 +36,6 @@ int main()
     static_assert((std::is_same<C::time_point::clock, C>::value), "");
     static_assert((C::is_steady || !C::is_steady), "");
     test(std::chrono::system_clock::is_steady);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.system/from_time_t.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.system/from_time_t.pass.cpp
index e6acef241c6..54252718d4a 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.system/from_time_t.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.system/from_time_t.pass.cpp
@@ -15,9 +15,11 @@
 #include <chrono>
 #include <ctime>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock C;
     C::time_point t1 = C::from_time_t(C::to_time_t(C::now()));
     ((void)t1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.system/local_time.types.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.system/local_time.types.pass.cpp
index 398cdb9d760..5802166c876 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.system/local_time.types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.system/local_time.types.pass.cpp
@@ -26,7 +26,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using local_t = std::chrono::local_t;
     using year    = std::chrono::year;
@@ -61,4 +61,6 @@ int main()
     ASSERT_SAME_TYPE(decltype(s0.time_since_epoch()), seconds);
     assert( s0.time_since_epoch().count() == 0);
     assert( s1.time_since_epoch().count() == 946684800L);
+
+    return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.system/now.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.system/now.pass.cpp
index 00a163685f6..9d74541f989 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.system/now.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.system/now.pass.cpp
@@ -15,11 +15,13 @@
 #include <chrono>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock C;
     C::time_point t1 = C::now();
     assert(t1.time_since_epoch().count() != 0);
     assert(C::time_point::min() < t1);
     assert(C::time_point::max() > t1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.system/rep_signed.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.system/rep_signed.pass.cpp
index cae8375d873..967af52e11d 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.system/rep_signed.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.system/rep_signed.pass.cpp
@@ -15,8 +15,10 @@
 #include <chrono>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::chrono::system_clock::duration::min() <
            std::chrono::system_clock::duration::zero());
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.system/sys.time.types.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.system/sys.time.types.pass.cpp
index 516f54914fd..174fbe94144 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.system/sys.time.types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.system/sys.time.types.pass.cpp
@@ -25,7 +25,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using system_clock = std::chrono::system_clock;
     using year         = std::chrono::year;
@@ -60,4 +60,6 @@ int main()
     ASSERT_SAME_TYPE(decltype(s0.time_since_epoch()), seconds);
     assert( s0.time_since_epoch().count() == 0);
     assert( s1.time_since_epoch().count() == 946684800L);
+
+    return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.clock/time.clock.system/to_time_t.pass.cpp b/libcxx/test/std/utilities/time/time.clock/time.clock.system/to_time_t.pass.cpp
index 0819a7b547f..86b37bb6bd1 100644
--- a/libcxx/test/std/utilities/time/time.clock/time.clock.system/to_time_t.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.clock/time.clock.system/to_time_t.pass.cpp
@@ -15,9 +15,11 @@
 #include <chrono>
 #include <ctime>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock C;
     std::time_t t1 = C::to_time_t(C::now());
     ((void)t1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/default_ratio.pass.cpp b/libcxx/test/std/utilities/time/time.duration/default_ratio.pass.cpp
index 92c015eef32..08870488c16 100644
--- a/libcxx/test/std/utilities/time/time.duration/default_ratio.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/default_ratio.pass.cpp
@@ -18,8 +18,10 @@
 #include <chrono>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_same<std::chrono::duration<int, std::ratio<1> >,
                    std::chrono::duration<int> >::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/duration.fail.cpp b/libcxx/test/std/utilities/time/time.duration/duration.fail.cpp
index 94e239c1f7c..02029c02bbe 100644
--- a/libcxx/test/std/utilities/time/time.duration/duration.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/duration.fail.cpp
@@ -15,8 +15,10 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::duration<std::chrono::milliseconds> D;
     D d;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/positive_num.fail.cpp b/libcxx/test/std/utilities/time/time.duration/positive_num.fail.cpp
index 6e78f776561..737576205cf 100644
--- a/libcxx/test/std/utilities/time/time.duration/positive_num.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/positive_num.fail.cpp
@@ -14,8 +14,10 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::duration<int, std::ratio<5, -1> > D;
     D d;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/ratio.fail.cpp b/libcxx/test/std/utilities/time/time.duration/ratio.fail.cpp
index 21873788a36..20298b772cb 100644
--- a/libcxx/test/std/utilities/time/time.duration/ratio.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/ratio.fail.cpp
@@ -22,8 +22,10 @@ public:
     static const int den = D;
 };
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::duration<int, Ratio<1> > D;
     D d;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.alg/abs.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.alg/abs.fail.cpp
index 6331dc95a9a..8d807c7a9b3 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.alg/abs.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.alg/abs.fail.cpp
@@ -20,7 +20,9 @@
 
 typedef std::chrono::duration<unsigned> unsigned_secs;
 
-int main()
+int main(int, char**)
 {
     std::chrono::abs(unsigned_secs(0));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.alg/abs.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.alg/abs.pass.cpp
index 5cb52ba7623..06f9a7c7f03 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.alg/abs.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.alg/abs.pass.cpp
@@ -30,7 +30,7 @@ test(const Duration& f, const Duration& d)
     }
 }
 
-int main()
+int main(int, char**)
 {
 //  7290000ms is 2 hours, 1 minute, and 30 seconds
     test(std::chrono::milliseconds( 7290000), std::chrono::milliseconds( 7290000));
@@ -46,4 +46,6 @@ int main()
     constexpr std::chrono::hours h2 = std::chrono::abs(std::chrono::hours(3));
     static_assert(h2.count() == 3, "");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_++.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_++.pass.cpp
index 9d6566a082c..d0e47b7fa8d 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_++.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_++.pass.cpp
@@ -25,7 +25,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::hours h(3);
@@ -37,4 +37,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_++int.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_++int.pass.cpp
index 78beffe2617..084819af3ce 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_++int.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_++int.pass.cpp
@@ -26,7 +26,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::hours h1(3);
@@ -38,4 +38,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_+.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_+.pass.cpp
index 0b8f49fc38f..a9d136f792a 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_+.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_+.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     const std::chrono::minutes m(3);
@@ -42,4 +42,6 @@ int main()
     static_assert( (std::is_same< decltype(zero+one), D1>::value), "");
     static_assert( (std::is_same< decltype(+one),     D1>::value), "");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_+=.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_+=.pass.cpp
index 0e907b573b2..4247f2d5689 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_+=.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_+=.pass.cpp
@@ -28,7 +28,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::seconds s(3);
@@ -41,4 +41,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_--.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_--.pass.cpp
index c9f1278a376..cfdb7075b37 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_--.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_--.pass.cpp
@@ -25,7 +25,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::hours h(3);
@@ -37,4 +37,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_--int.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_--int.pass.cpp
index 5abecee1648..4afb86e0caf 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_--int.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_--int.pass.cpp
@@ -27,7 +27,7 @@ constexpr bool test_constexpr()
 #endif
 
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::hours h1(3);
@@ -39,4 +39,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_-.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_-.pass.cpp
index f7ab6d2e299..fe065ff5f99 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_-.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_-.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     const std::chrono::minutes m(3);
@@ -43,4 +43,6 @@ int main()
     static_assert( (std::is_same< decltype(-one),     D1>::value), "");
     static_assert( (std::is_same< decltype(+one),     D1>::value), "");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_-=.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_-=.pass.cpp
index 1752d5257b8..b457619e154 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_-=.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_-=.pass.cpp
@@ -28,7 +28,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::seconds s(3);
@@ -41,4 +41,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_divide=.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_divide=.pass.cpp
index 4f79398f73b..753ea5a8bc1 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_divide=.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_divide=.pass.cpp
@@ -26,7 +26,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::nanoseconds ns(15);
@@ -37,4 +37,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_mod=duration.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_mod=duration.pass.cpp
index 89b550d015c..649f4aa1a4c 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_mod=duration.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_mod=duration.pass.cpp
@@ -27,7 +27,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::microseconds us1(11);
@@ -41,4 +41,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_mod=rep.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_mod=rep.pass.cpp
index 8ef16c7ff7c..0eb73ee674f 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_mod=rep.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_mod=rep.pass.cpp
@@ -26,7 +26,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::microseconds us(11);
@@ -37,4 +37,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_times=.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_times=.pass.cpp
index b4b76fb6f50..51c20c50764 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_times=.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.arithmetic/op_times=.pass.cpp
@@ -26,7 +26,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::nanoseconds ns(3);
@@ -37,4 +37,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/ceil.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/ceil.fail.cpp
index e557bc21fb5..a9711f448c8 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/ceil.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/ceil.fail.cpp
@@ -19,7 +19,9 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     std::chrono::ceil<int>(std::chrono::milliseconds(3));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/ceil.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/ceil.pass.cpp
index b509182c41e..a6e1982d044 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/ceil.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/ceil.pass.cpp
@@ -32,7 +32,7 @@ test(const FromDuration& f, const ToDuration& d)
     }
 }
 
-int main()
+int main(int, char**)
 {
 //  7290000ms is 2 hours, 1 minute, and 30 seconds
     test(std::chrono::milliseconds( 7290000), std::chrono::hours( 3));
@@ -47,4 +47,6 @@ int main()
     constexpr std::chrono::hours h2 = std::chrono::ceil<std::chrono::hours>(std::chrono::milliseconds(-9000000));
     static_assert(h2.count() == -2, "");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/duration_cast.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/duration_cast.pass.cpp
index 5187d3d0e7c..4151756764a 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/duration_cast.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/duration_cast.pass.cpp
@@ -32,7 +32,7 @@ test(const FromDuration& f, const ToDuration& d)
     }
 }
 
-int main()
+int main(int, char**)
 {
     test(std::chrono::milliseconds(7265000), std::chrono::hours(2));
     test(std::chrono::milliseconds(7265000), std::chrono::minutes(121));
@@ -50,4 +50,6 @@ int main()
     static_assert(h.count() == 2, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/floor.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/floor.fail.cpp
index 62dd5a51d60..c119a800cfa 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/floor.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/floor.fail.cpp
@@ -19,7 +19,9 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     std::chrono::floor<int>(std::chrono::milliseconds(3));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/floor.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/floor.pass.cpp
index 29142bdcf3e..6783b1f67ed 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/floor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/floor.pass.cpp
@@ -31,7 +31,7 @@ test(const FromDuration& f, const ToDuration& d)
     }
 }
 
-int main()
+int main(int, char**)
 {
 //  7290000ms is 2 hours, 1 minute, and 30 seconds
     test(std::chrono::milliseconds( 7290000), std::chrono::hours( 2));
@@ -46,4 +46,6 @@ int main()
     constexpr std::chrono::hours h2 = std::chrono::floor<std::chrono::hours>(std::chrono::milliseconds(-9000000));
     static_assert(h2.count() == -3, "");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/round.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/round.fail.cpp
index aadfbfdc47e..93366b83618 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/round.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/round.fail.cpp
@@ -19,7 +19,9 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     std::chrono::round<int>(std::chrono::milliseconds(3));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/round.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/round.pass.cpp
index b0789b7917d..ebd2e3194a4 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/round.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/round.pass.cpp
@@ -31,7 +31,7 @@ test(const FromDuration& f, const ToDuration& d)
     }
 }
 
-int main()
+int main(int, char**)
 {
 //  7290000ms is 2 hours, 1 minute, and 30 seconds
     test(std::chrono::milliseconds( 7290000), std::chrono::hours( 2));
@@ -46,4 +46,6 @@ int main()
     constexpr std::chrono::hours h2 = std::chrono::round<std::chrono::hours>(std::chrono::milliseconds(-9000000));
     static_assert(h2.count() == -2, "");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/toduration.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/toduration.fail.cpp
index a46aa526bda..0f52c36d86c 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cast/toduration.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cast/toduration.fail.cpp
@@ -18,7 +18,9 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     std::chrono::duration_cast<int>(std::chrono::milliseconds(3));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.comparisons/op_equal.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.comparisons/op_equal.pass.cpp
index 912d22fdf0e..c27b528017e 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.comparisons/op_equal.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.comparisons/op_equal.pass.cpp
@@ -25,7 +25,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::seconds s1(3);
@@ -113,4 +113,6 @@ int main()
     static_assert(!(s1 != s2), "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.comparisons/op_less.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.comparisons/op_less.pass.cpp
index 9eea6ceb3bd..de476357650 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.comparisons/op_less.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.comparisons/op_less.pass.cpp
@@ -35,7 +35,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::seconds s1(3);
@@ -151,4 +151,6 @@ int main()
     static_assert( (s1 >= s2), "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_exact.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_exact.pass.cpp
index 0f6fb8d3590..4c0af92b23d 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_exact.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_exact.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::milliseconds ms(1);
@@ -34,4 +34,6 @@ int main()
     static_assert(us.count() == 1000, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_float_to_int.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_float_to_int.fail.cpp
index b35c01c40ec..4311c1bde38 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_float_to_int.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_float_to_int.fail.cpp
@@ -17,8 +17,10 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     std::chrono::duration<double> d;
     std::chrono::duration<int> i = d;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_inexact.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_inexact.fail.cpp
index b66b2f3c601..fb0b488f7d8 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_inexact.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_inexact.fail.cpp
@@ -17,8 +17,10 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     std::chrono::microseconds us(1);
     std::chrono::milliseconds ms = us;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_inexact.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_inexact.pass.cpp
index 5624327badc..f72c69c7ef1 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_inexact.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_inexact.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::duration<double, std::micro> us(1);
@@ -34,4 +34,6 @@ int main()
     static_assert(ms.count() == 1./1000, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_int_to_float.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_int_to_float.pass.cpp
index a63471bc37d..fb127226a6c 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_int_to_float.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_int_to_float.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::duration<int> i(3);
@@ -34,4 +34,6 @@ int main()
     static_assert(d.count() == 3000, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_overflow.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_overflow.pass.cpp
index 68484d1fb51..5b963f2b1f4 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_overflow.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/convert_overflow.pass.cpp
@@ -26,11 +26,13 @@ void f(std::chrono::seconds)
     called = true;
 }
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::duration<int, std::exa> r(1);
     f(r);
     assert(called);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/default.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/default.pass.cpp
index 9edcd46f902..c598afa3651 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/default.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/default.pass.cpp
@@ -32,7 +32,9 @@ test()
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     test<std::chrono::duration<Rep> >();
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep.pass.cpp
index f89263bf9b0..d1a808ba154 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep.pass.cpp
@@ -31,10 +31,12 @@ test(R r)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     test<std::chrono::duration<int> >(5);
     test<std::chrono::duration<int, std::ratio<3, 2> > >(5);
     test<std::chrono::duration<Rep, std::ratio<3, 2> > >(Rep(3));
     test<std::chrono::duration<double, std::ratio<2, 3> > >(5.5);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep01.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep01.fail.cpp
index fc6f5700a6a..f1e60f5e54d 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep01.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep01.fail.cpp
@@ -19,7 +19,9 @@
 
 #include "../../rep.h"
 
-int main()
+int main(int, char**)
 {
     std::chrono::duration<int> d = 1;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep02.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep02.fail.cpp
index bdbe7211b81..4a09325065c 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep02.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep02.fail.cpp
@@ -19,7 +19,9 @@
 
 #include "../../rep.h"
 
-int main()
+int main(int, char**)
 {
     std::chrono::duration<Rep> d(1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep02.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep02.pass.cpp
index 3ecb76135e1..1719b1302ba 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep02.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep02.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     std::chrono::duration<double> d(5);
     assert(d.count() == 5);
@@ -28,4 +28,6 @@ int main()
     constexpr std::chrono::duration<double> d2(5);
     static_assert(d2.count() == 5, "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep03.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep03.fail.cpp
index 831370994ee..6b4d0020379 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep03.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.cons/rep03.fail.cpp
@@ -17,7 +17,9 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     std::chrono::duration<int> d(1.);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals.pass.cpp
index 13ad165b7bf..0d924f8f70b 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals.pass.cpp
@@ -15,7 +15,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     using namespace std::literals::chrono_literals;
 
@@ -57,4 +57,6 @@ int main()
     auto ns2 = 645.ns;
     assert ( ns == ns2 );
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals1.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals1.fail.cpp
index 025100c5928..97e29e87682 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals1.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals1.fail.cpp
@@ -11,8 +11,10 @@
 #include <chrono>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     std::chrono::hours h  = 4h;  // should fail w/conversion operator not found
+
+  return 0;
 }
 
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals1.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals1.pass.cpp
index 9ca29086777..2e5b7bbb87b 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals1.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals1.pass.cpp
@@ -11,7 +11,7 @@
 #include <chrono>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     using namespace std::chrono;
 
@@ -67,4 +67,6 @@ int main()
     assert(November  == month(11));
     assert(December  == month(12));
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals2.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals2.fail.cpp
index 5c38db52713..dbc91559031 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals2.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals2.fail.cpp
@@ -11,9 +11,11 @@
 #include <chrono>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     using std::chrono::hours;
 
     hours foo  =  4h;  // should fail w/conversion operator not found
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals2.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals2.pass.cpp
index 40709103254..d0b8b33e493 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals2.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.literals/literals2.pass.cpp
@@ -13,7 +13,7 @@
 #include <type_traits>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     using namespace std::literals;
 
@@ -46,4 +46,6 @@ int main()
     assert ( ns == std::chrono::nanoseconds(645));
     auto ns2 = 645.ns;
     assert ( ns == ns2 );
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_+.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_+.pass.cpp
index 30aa62cd9d1..ad381f00565 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_+.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_+.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::seconds s1(3);
@@ -71,4 +71,6 @@ int main()
     static_assert(r.count() == 75, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_-.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_-.pass.cpp
index cb0a53fdf54..86ced3fbcbd 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_-.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_-.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::seconds s1(3);
@@ -72,4 +72,6 @@ int main()
     static_assert(r.count() == -15, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_divide_duration.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_divide_duration.pass.cpp
index 40f521bae01..e4190fe3385 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_divide_duration.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_divide_duration.pass.cpp
@@ -21,7 +21,7 @@
 #include "test_macros.h"
 #include "truncate_fp.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::nanoseconds ns1(15);
@@ -65,4 +65,6 @@ int main()
     static_assert(s1 / s2 == 20./3, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_divide_rep.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_divide_rep.fail.cpp
index 41c55fccaeb..327ff563567 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_divide_rep.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_divide_rep.fail.cpp
@@ -18,8 +18,10 @@
 
 #include "../../rep.h"
 
-int main()
+int main(int, char**)
 {
     std::chrono::duration<Rep> d(Rep(15));
     d = d / 5;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_divide_rep.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_divide_rep.pass.cpp
index 8718ad75730..94da11302bf 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_divide_rep.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_divide_rep.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::nanoseconds ns(15);
@@ -34,4 +34,6 @@ int main()
     static_assert(ns2.count() == 3, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_mod_duration.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_mod_duration.pass.cpp
index 7a2063ca54e..e7007c1fe35 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_mod_duration.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_mod_duration.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::nanoseconds ns1(15);
@@ -60,4 +60,6 @@ int main()
     static_assert(r.count() == 24, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_mod_rep.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_mod_rep.fail.cpp
index 3ee0578f805..f2a5885aba6 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_mod_rep.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_mod_rep.fail.cpp
@@ -18,8 +18,10 @@
 
 #include "../../rep.h"
 
-int main()
+int main(int, char**)
 {
     std::chrono::duration<Rep> d(Rep(15));
     d = d % 5;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_mod_rep.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_mod_rep.pass.cpp
index 6d7e285d9b8..754b9800a7d 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_mod_rep.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_mod_rep.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::nanoseconds ns(15);
@@ -34,4 +34,6 @@ int main()
     static_assert(ns2.count() == 3, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_times_rep.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_times_rep.pass.cpp
index 19e33366f71..c3e49963808 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_times_rep.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_times_rep.pass.cpp
@@ -25,7 +25,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::chrono::nanoseconds ns(3);
@@ -43,4 +43,6 @@ int main()
     static_assert(ns3.count() == 18, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_times_rep1.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_times_rep1.fail.cpp
index 6ad3c7928a9..44a77cea18a 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_times_rep1.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_times_rep1.fail.cpp
@@ -22,8 +22,10 @@
 
 #include "../../rep.h"
 
-int main()
+int main(int, char**)
 {
     std::chrono::duration<Rep> d;
     d = d * 5;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_times_rep2.fail.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_times_rep2.fail.cpp
index 5cc717c5c04..9ce82582cf3 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_times_rep2.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.nonmember/op_times_rep2.fail.cpp
@@ -22,8 +22,10 @@
 
 #include "../../rep.h"
 
-int main()
+int main(int, char**)
 {
     std::chrono::duration<Rep> d;
     d = 5 * d;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.observer/tested_elsewhere.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.observer/tested_elsewhere.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.observer/tested_elsewhere.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.observer/tested_elsewhere.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.special/max.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.special/max.pass.cpp
index c6f3f1e6547..58de66a0158 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.special/max.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.special/max.pass.cpp
@@ -40,8 +40,10 @@ void test()
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     test<std::chrono::duration<int> >();
     test<std::chrono::duration<Rep> >();
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.special/min.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.special/min.pass.cpp
index b16e608dcc7..9b0113b2980 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.special/min.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.special/min.pass.cpp
@@ -40,8 +40,10 @@ void test()
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     test<std::chrono::duration<int> >();
     test<std::chrono::duration<Rep> >();
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/time.duration.special/zero.pass.cpp b/libcxx/test/std/utilities/time/time.duration/time.duration.special/zero.pass.cpp
index f3065c30542..34a05b5f071 100644
--- a/libcxx/test/std/utilities/time/time.duration/time.duration.special/zero.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/time.duration.special/zero.pass.cpp
@@ -39,8 +39,10 @@ void test()
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     test<std::chrono::duration<int> >();
     test<std::chrono::duration<Rep> >();
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.duration/types.pass.cpp b/libcxx/test/std/utilities/time/time.duration/types.pass.cpp
index 9e5abbc20a7..250e532859e 100644
--- a/libcxx/test/std/utilities/time/time.duration/types.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.duration/types.pass.cpp
@@ -18,9 +18,11 @@
 #include <chrono>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::duration<long, std::ratio<3, 2> > D;
     static_assert((std::is_same<D::rep, long>::value), "");
     static_assert((std::is_same<D::period, std::ratio<3, 2> >::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/default_duration.pass.cpp b/libcxx/test/std/utilities/time/time.point/default_duration.pass.cpp
index e645e2970c6..8a58413a0aa 100644
--- a/libcxx/test/std/utilities/time/time.point/default_duration.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/default_duration.pass.cpp
@@ -18,8 +18,10 @@
 #include <chrono>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_same<std::chrono::system_clock::duration,
                    std::chrono::time_point<std::chrono::system_clock>::duration>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/duration.fail.cpp b/libcxx/test/std/utilities/time/time.point/duration.fail.cpp
index a4881acc931..6461eb3d96f 100644
--- a/libcxx/test/std/utilities/time/time.point/duration.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.point/duration.fail.cpp
@@ -14,8 +14,10 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::time_point<std::chrono::system_clock, int> T;
     T t;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.arithmetic/op_+=.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.arithmetic/op_+=.pass.cpp
index 999071b72c6..002fffc3882 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.arithmetic/op_+=.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.arithmetic/op_+=.pass.cpp
@@ -29,7 +29,7 @@ constexpr bool constexpr_test()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::chrono::system_clock Clock;
@@ -42,4 +42,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(constexpr_test(), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.arithmetic/op_-=.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.arithmetic/op_-=.pass.cpp
index 3d62cdedaac..2365d539ca7 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.arithmetic/op_-=.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.arithmetic/op_-=.pass.cpp
@@ -29,7 +29,7 @@ constexpr bool constexpr_test()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::chrono::system_clock Clock;
@@ -42,4 +42,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(constexpr_test(), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cast/ceil.fail.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cast/ceil.fail.cpp
index 4a90ec870cf..fb82fdffe4d 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cast/ceil.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cast/ceil.fail.cpp
@@ -19,7 +19,9 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     std::chrono::ceil<int>(std::chrono::system_clock::now());
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cast/ceil.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cast/ceil.pass.cpp
index efd2a3e592b..8dfd1bdaa38 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cast/ceil.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cast/ceil.pass.cpp
@@ -49,7 +49,7 @@ void test_constexpr ()
 }
 
 
-int main()
+int main(int, char**)
 {
 //  7290000ms is 2 hours, 1 minute, and 30 seconds
     test(std::chrono::milliseconds( 7290000), std::chrono::hours( 3));
@@ -65,4 +65,6 @@ int main()
 
     test_constexpr<std::chrono::milliseconds, 9000000, std::chrono::seconds, 9000> ();
     test_constexpr<std::chrono::milliseconds,-9000000, std::chrono::seconds,-9000> ();
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cast/floor.fail.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cast/floor.fail.cpp
index c5dfba6c4f1..12b1dec9fd5 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cast/floor.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cast/floor.fail.cpp
@@ -19,7 +19,9 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     std::chrono::floor<int>(std::chrono::system_clock::now());
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cast/floor.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cast/floor.pass.cpp
index db2391d2518..d50fff4a1c8 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cast/floor.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cast/floor.pass.cpp
@@ -48,7 +48,7 @@ void test_constexpr ()
     }
 }
 
-int main()
+int main(int, char**)
 {
 //  7290000ms is 2 hours, 1 minute, and 30 seconds
     test(std::chrono::milliseconds( 7290000), std::chrono::hours( 2));
@@ -64,4 +64,6 @@ int main()
 
     test_constexpr<std::chrono::milliseconds, 9000000, std::chrono::seconds, 9000> ();
     test_constexpr<std::chrono::milliseconds,-9000000, std::chrono::seconds,-9000> ();
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cast/round.fail.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cast/round.fail.cpp
index 6c6f9c5bf5c..a5436c68404 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cast/round.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cast/round.fail.cpp
@@ -19,7 +19,9 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     std::chrono::round<int>(std::chrono::system_clock::now());
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cast/round.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cast/round.pass.cpp
index e68e233969d..d8bb1b505b1 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cast/round.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cast/round.pass.cpp
@@ -48,7 +48,7 @@ void test_constexpr ()
     }
 }
 
-int main()
+int main(int, char**)
 {
 //  7290000ms is 2 hours, 1 minute, and 30 seconds
     test(std::chrono::milliseconds( 7290000), std::chrono::hours( 2));
@@ -64,4 +64,6 @@ int main()
 
     test_constexpr<std::chrono::milliseconds, 9000000, std::chrono::seconds, 9000> ();
     test_constexpr<std::chrono::milliseconds,-9000000, std::chrono::seconds,-9000> ();
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cast/time_point_cast.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cast/time_point_cast.pass.cpp
index 5779ef9208a..90e6ccef666 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cast/time_point_cast.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cast/time_point_cast.pass.cpp
@@ -54,7 +54,7 @@ void test_constexpr ()
 
 #endif
 
-int main()
+int main(int, char**)
 {
     test(std::chrono::milliseconds(7265000), std::chrono::hours(2));
     test(std::chrono::milliseconds(7265000), std::chrono::minutes(121));
@@ -78,4 +78,6 @@ int main()
     test_constexpr<std::chrono::duration<int, std::ratio<2, 3>>, 9, T1, 10> ();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cast/toduration.fail.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cast/toduration.fail.cpp
index 9e1f903b93f..c16492f730a 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cast/toduration.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cast/toduration.fail.cpp
@@ -18,10 +18,12 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::time_point<Clock, std::chrono::milliseconds> FromTimePoint;
     typedef std::chrono::time_point<Clock, std::chrono::minutes> ToTimePoint;
     std::chrono::time_point_cast<ToTimePoint>(FromTimePoint(std::chrono::milliseconds(3)));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_equal.fail.cpp b/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_equal.fail.cpp
index e2b3508e000..2b5795026b3 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_equal.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_equal.fail.cpp
@@ -24,7 +24,7 @@
 
 #include "../../clock.h"
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock1;
     typedef Clock                     Clock2;
@@ -36,4 +36,6 @@ int main()
     T1 t1(Duration1(3));
     T2 t2(Duration2(3000));
     t1 == t2;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_equal.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_equal.pass.cpp
index cc2ef333763..f110ec5d406 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_equal.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_equal.pass.cpp
@@ -23,7 +23,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::milliseconds Duration1;
@@ -82,4 +82,6 @@ int main()
     static_assert( (t1 != t2), "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_less.fail.cpp b/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_less.fail.cpp
index 04f7639d605..3d158ea890f 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_less.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_less.fail.cpp
@@ -32,7 +32,7 @@
 
 #include "../../clock.h"
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock1;
     typedef Clock                     Clock2;
@@ -44,4 +44,6 @@ int main()
     T1 t1(Duration1(3));
     T2 t2(Duration2(3000));
     t1 < t2;
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_less.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_less.pass.cpp
index 57d24d08d02..3b4aa6abecf 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_less.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.comparisons/op_less.pass.cpp
@@ -31,7 +31,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::milliseconds Duration1;
@@ -106,4 +106,6 @@ int main()
     static_assert(!(t1 >= t2), "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cons/convert.fail.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cons/convert.fail.cpp
index a68d4b0f304..2e601179a7d 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cons/convert.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cons/convert.fail.cpp
@@ -17,7 +17,7 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::milliseconds Duration1;
@@ -26,4 +26,6 @@ int main()
     std::chrono::time_point<Clock, Duration2> t2(Duration2(3));
     std::chrono::time_point<Clock, Duration1> t1 = t2;
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cons/convert.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cons/convert.pass.cpp
index 91bcebb1a91..f9b35c95738 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cons/convert.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cons/convert.pass.cpp
@@ -18,7 +18,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::microseconds Duration1;
@@ -35,4 +35,6 @@ int main()
     static_assert(t1.time_since_epoch() == Duration1(3000), "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cons/default.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cons/default.pass.cpp
index 2deb8ae298c..b40113999a5 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cons/default.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cons/default.pass.cpp
@@ -18,7 +18,7 @@
 #include "test_macros.h"
 #include "../../rep.h"
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::duration<Rep, std::milli> Duration;
@@ -32,4 +32,6 @@ int main()
     static_assert(t.time_since_epoch() == Duration::zero(), "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cons/duration.fail.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cons/duration.fail.cpp
index 4a42eef3057..b28116236d0 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cons/duration.fail.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cons/duration.fail.cpp
@@ -16,9 +16,11 @@
 
 #include <chrono>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::milliseconds Duration;
     std::chrono::time_point<Clock, Duration> t = Duration(3);
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.cons/duration.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.cons/duration.pass.cpp
index 0830eea9119..078c6641e76 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.cons/duration.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.cons/duration.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::milliseconds Duration;
@@ -39,4 +39,6 @@ int main()
     static_assert(t.time_since_epoch() == Duration(3000), "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.nonmember/op_+.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.nonmember/op_+.pass.cpp
index df6c691572e..7d78f7f4329 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.nonmember/op_+.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.nonmember/op_+.pass.cpp
@@ -23,7 +23,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::milliseconds Duration1;
@@ -44,4 +44,6 @@ int main()
     static_assert(t3.time_since_epoch() == Duration2(3006), "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.nonmember/op_-duration.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.nonmember/op_-duration.pass.cpp
index 876d42d560d..6fe8769695b 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.nonmember/op_-duration.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.nonmember/op_-duration.pass.cpp
@@ -30,7 +30,7 @@ void test2739()  // LWG2739
     assert(t1 < t0);
 }
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::milliseconds Duration1;
@@ -49,4 +49,6 @@ int main()
 #endif
     test2739<int32_t>();
     test2739<uint32_t>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.nonmember/op_-time_point.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.nonmember/op_-time_point.pass.cpp
index 851869d4d0d..22e4520f360 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.nonmember/op_-time_point.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.nonmember/op_-time_point.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::milliseconds Duration1;
@@ -36,4 +36,6 @@ int main()
     static_assert((t1 - t2) == Duration2(2995), "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.observer/tested_elsewhere.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.observer/tested_elsewhere.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.observer/tested_elsewhere.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.observer/tested_elsewhere.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.special/max.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.special/max.pass.cpp
index c8f2d41be97..e7826b1a610 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.special/max.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.special/max.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::milliseconds Duration;
@@ -27,4 +27,6 @@ int main()
     ASSERT_NOEXCEPT(       TP::max());
 #endif
     assert(TP::max() == TP(Duration::max()));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.point/time.point.special/min.pass.cpp b/libcxx/test/std/utilities/time/time.point/time.point.special/min.pass.cpp
index 1cac230624f..fae3339b03d 100644
--- a/libcxx/test/std/utilities/time/time.point/time.point.special/min.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.point/time.point.special/min.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::system_clock Clock;
     typedef std::chrono::milliseconds Duration;
@@ -27,4 +27,6 @@ int main()
     ASSERT_NOEXCEPT(       TP::max());
 #endif
     assert(TP::min() == TP(Duration::min()));
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.traits/nothing_to_do.pass.cpp b/libcxx/test/std/utilities/time/time.traits/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/utilities/time/time.traits/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.traits/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.traits/time.traits.duration_values/max.pass.cpp b/libcxx/test/std/utilities/time/time.traits/time.traits.duration_values/max.pass.cpp
index f44a7964f02..8d244c77346 100644
--- a/libcxx/test/std/utilities/time/time.traits/time.traits.duration_values/max.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.traits/time.traits.duration_values/max.pass.cpp
@@ -17,7 +17,7 @@
 #include "test_macros.h"
 #include "../../rep.h"
 
-int main()
+int main(int, char**)
 {
     assert(std::chrono::duration_values<int>::max() ==
            std::numeric_limits<int>::max());
@@ -42,4 +42,6 @@ int main()
     ASSERT_NOEXCEPT(std::chrono::duration_values<double>::max());
     ASSERT_NOEXCEPT(std::chrono::duration_values<Rep>::max());
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.traits/time.traits.duration_values/min.pass.cpp b/libcxx/test/std/utilities/time/time.traits/time.traits.duration_values/min.pass.cpp
index c64746d9fc7..4ff03c62286 100644
--- a/libcxx/test/std/utilities/time/time.traits/time.traits.duration_values/min.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.traits/time.traits.duration_values/min.pass.cpp
@@ -17,7 +17,7 @@
 #include "test_macros.h"
 #include "../../rep.h"
 
-int main()
+int main(int, char**)
 {
     assert(std::chrono::duration_values<int>::min() ==
            std::numeric_limits<int>::lowest());
@@ -42,4 +42,6 @@ int main()
     ASSERT_NOEXCEPT(std::chrono::duration_values<double>::min());
     ASSERT_NOEXCEPT(std::chrono::duration_values<Rep>::min());
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.traits/time.traits.duration_values/zero.pass.cpp b/libcxx/test/std/utilities/time/time.traits/time.traits.duration_values/zero.pass.cpp
index 6eec47ce3b0..d9de07b414e 100644
--- a/libcxx/test/std/utilities/time/time.traits/time.traits.duration_values/zero.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.traits/time.traits.duration_values/zero.pass.cpp
@@ -16,7 +16,7 @@
 #include "test_macros.h"
 #include "../../rep.h"
 
-int main()
+int main(int, char**)
 {
     assert(std::chrono::duration_values<int>::zero() == 0);
     assert(std::chrono::duration_values<Rep>::zero() == 0);
@@ -31,4 +31,6 @@ int main()
     ASSERT_NOEXCEPT(std::chrono::duration_values<int>::zero());
     ASSERT_NOEXCEPT(std::chrono::duration_values<Rep>::zero());
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.traits/time.traits.is_fp/treat_as_floating_point.pass.cpp b/libcxx/test/std/utilities/time/time.traits/time.traits.is_fp/treat_as_floating_point.pass.cpp
index cf588f5c0af..9db3d96d26d 100644
--- a/libcxx/test/std/utilities/time/time.traits/time.traits.is_fp/treat_as_floating_point.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.traits/time.traits.is_fp/treat_as_floating_point.pass.cpp
@@ -29,7 +29,7 @@ test()
 
 struct A {};
 
-int main()
+int main(int, char**)
 {
     test<int>();
     test<unsigned>();
@@ -39,4 +39,6 @@ int main()
     test<double>();
     test<long double>();
     test<A>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.traits/time.traits.specializations/duration.pass.cpp b/libcxx/test/std/utilities/time/time.traits/time.traits.specializations/duration.pass.cpp
index 39afe6a5f53..3dde5404727 100644
--- a/libcxx/test/std/utilities/time/time.traits/time.traits.specializations/duration.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.traits/time.traits.specializations/duration.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert((std::is_same<Dc, De>::value), "");
 }
 
-int main()
+int main(int, char**)
 {
     test<std::chrono::duration<int, std::ratio<1, 100> >,
          std::chrono::duration<long, std::ratio<1, 1000> >,
@@ -38,4 +38,6 @@ int main()
     test<std::chrono::duration<double, std::ratio<21, 1> >,
          std::chrono::duration<short, std::ratio<15, 1> >,
          std::chrono::duration<double, std::ratio<3, 1> > >();
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/time.traits/time.traits.specializations/time_point.pass.cpp b/libcxx/test/std/utilities/time/time.traits/time.traits.specializations/time_point.pass.cpp
index bf880fcd2b7..d73bb8ae6fd 100644
--- a/libcxx/test/std/utilities/time/time.traits/time.traits.specializations/time_point.pass.cpp
+++ b/libcxx/test/std/utilities/time/time.traits/time.traits.specializations/time_point.pass.cpp
@@ -28,7 +28,7 @@ test()
     static_assert((std::is_same<Tc, Te>::value), "");
 }
 
-int main()
+int main(int, char**)
 {
     test<std::chrono::duration<int, std::ratio<1, 100> >,
          std::chrono::duration<long, std::ratio<1, 1000> >,
@@ -42,4 +42,6 @@ int main()
     test<std::chrono::duration<double, std::ratio<21, 1> >,
          std::chrono::duration<short, std::ratio<15, 1> >,
          std::chrono::duration<double, std::ratio<3, 1> > >();
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/weeks.pass.cpp b/libcxx/test/std/utilities/time/weeks.pass.cpp
index 2231c69550c..5a0cf3417f5 100644
--- a/libcxx/test/std/utilities/time/weeks.pass.cpp
+++ b/libcxx/test/std/utilities/time/weeks.pass.cpp
@@ -15,7 +15,7 @@
 #include <type_traits>
 #include <limits>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::weeks D;
     typedef D::rep Rep;
@@ -24,4 +24,6 @@ int main()
     static_assert(std::is_integral<Rep>::value, "");
     static_assert(std::numeric_limits<Rep>::digits >= 22, "");
     static_assert(std::is_same_v<Period, std::ratio_multiply<std::ratio<7>, std::chrono::days::period>>, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/utilities/time/years.pass.cpp b/libcxx/test/std/utilities/time/years.pass.cpp
index c2229caee63..5016369268a 100644
--- a/libcxx/test/std/utilities/time/years.pass.cpp
+++ b/libcxx/test/std/utilities/time/years.pass.cpp
@@ -15,7 +15,7 @@
 #include <type_traits>
 #include <limits>
 
-int main()
+int main(int, char**)
 {
     typedef std::chrono::years D;
     typedef D::rep Rep;
@@ -24,4 +24,6 @@ int main()
     static_assert(std::is_integral<Rep>::value, "");
     static_assert(std::numeric_limits<Rep>::digits >= 17, "");
     static_assert(std::is_same_v<Period, std::ratio_multiply<std::ratio<146097, 400>, std::chrono::days::period>>, "");
+
+  return 0;
 }