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

32 files changed, 96 insertions, 32 deletions

diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/const_data_members.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/const_data_members.pass.cpp
index 012a9a8eef3..b5912130a8d 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/const_data_members.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/const_data_members.pass.cpp
@@ -68,7 +68,7 @@ void test(const T &) {}
 
 struct other {};
 
-int main()
+int main(int, char**)
 {
     // bool
     TEST_NUMERIC_LIMITS(bool)
@@ -205,4 +205,6 @@ int main()
     TEST_NUMERIC_LIMITS(const other)
     TEST_NUMERIC_LIMITS(volatile other)
     TEST_NUMERIC_LIMITS(const volatile other)
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/denorm_min.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/denorm_min.pass.cpp
index d67e8cbaba7..4f9f62873aa 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/denorm_min.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/denorm_min.pass.cpp
@@ -26,7 +26,7 @@ test(T expected)
     assert(std::numeric_limits<const volatile T>::denorm_min() == expected);
 }
 
-int main()
+int main(int, char**)
 {
     test<bool>(false);
     test<char>(0);
@@ -65,4 +65,6 @@ int main()
 #if !defined(__FLT_DENORM_MIN__) && !defined(FLT_TRUE_MIN)
 #error Test has no expected values for floating point types
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/digits.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/digits.pass.cpp
index de9aa3395d6..139f4821dc8 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/digits.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/digits.pass.cpp
@@ -25,7 +25,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::digits == expected, "digits test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, 1>();
     test<char, std::numeric_limits<char>::is_signed ? 7 : 8>();
@@ -54,4 +54,6 @@ int main()
     test<float, FLT_MANT_DIG>();
     test<double, DBL_MANT_DIG>();
     test<long double, LDBL_MANT_DIG>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/digits10.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/digits10.pass.cpp
index 9c2fcfb1797..efdfd70d79c 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/digits10.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/digits10.pass.cpp
@@ -29,7 +29,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::is_bounded, "digits10 test 8");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, 0>();
     test<char, 2>();
@@ -58,4 +58,6 @@ int main()
     test<float, FLT_DIG>();
     test<double, DBL_DIG>();
     test<long double, LDBL_DIG>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/epsilon.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/epsilon.pass.cpp
index 691bd5b2765..60a905f79bb 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/epsilon.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/epsilon.pass.cpp
@@ -26,7 +26,7 @@ test(T expected)
     assert(std::numeric_limits<const volatile T>::epsilon() == expected);
 }
 
-int main()
+int main(int, char**)
 {
     test<bool>(false);
     test<char>(0);
@@ -55,4 +55,6 @@ int main()
     test<float>(FLT_EPSILON);
     test<double>(DBL_EPSILON);
     test<long double>(LDBL_EPSILON);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_denorm.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_denorm.pass.cpp
index 05469f08c96..d5380c1a763 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_denorm.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_denorm.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::has_denorm == expected, "has_denorm test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, std::denorm_absent>();
     test<char, std::denorm_absent>();
@@ -53,4 +53,6 @@ int main()
     test<float, std::denorm_present>();
     test<double, std::denorm_present>();
     test<long double, std::denorm_present>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_denorm_loss.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_denorm_loss.pass.cpp
index 89bc78a48c2..77e5de6ab83 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_denorm_loss.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_denorm_loss.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::has_denorm_loss == expected, "has_denorm_loss test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, false>();
     test<char, false>();
@@ -53,4 +53,6 @@ int main()
     test<float, false>();
     test<double, false>();
     test<long double, false>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_infinity.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_infinity.pass.cpp
index abdd9b544ee..19d4fe29312 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_infinity.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_infinity.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::has_infinity == expected, "has_infinity test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, false>();
     test<char, false>();
@@ -53,4 +53,6 @@ int main()
     test<float, true>();
     test<double, true>();
     test<long double, true>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_quiet_NaN.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_quiet_NaN.pass.cpp
index a351bcef094..767df5ac27b 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_quiet_NaN.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_quiet_NaN.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::has_quiet_NaN == expected, "has_quiet_NaN test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, false>();
     test<char, false>();
@@ -53,4 +53,6 @@ int main()
     test<float, true>();
     test<double, true>();
     test<long double, true>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_signaling_NaN.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_signaling_NaN.pass.cpp
index bc74464e788..0908c49bc16 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_signaling_NaN.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/has_signaling_NaN.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::has_signaling_NaN == expected, "has_signaling_NaN test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, false>();
     test<char, false>();
@@ -53,4 +53,6 @@ int main()
     test<float, true>();
     test<double, true>();
     test<long double, true>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/infinity.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/infinity.pass.cpp
index 924f32a6b26..0004e4e6282 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/infinity.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/infinity.pass.cpp
@@ -28,7 +28,7 @@ test(T expected)
 
 extern float zero;
 
-int main()
+int main(int, char**)
 {
     test<bool>(false);
     test<char>(0);
@@ -57,6 +57,8 @@ int main()
     test<float>(1.f/zero);
     test<double>(1./zero);
     test<long double>(1./zero);
+
+  return 0;
 }
 
 float zero = 0;
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_bounded.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_bounded.pass.cpp
index 8f2cdb0a78f..d509be720e7 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_bounded.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_bounded.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::is_bounded == expected, "is_bounded test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, true>();
     test<char, true>();
@@ -53,4 +53,6 @@ int main()
     test<float, true>();
     test<double, true>();
     test<long double, true>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_exact.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_exact.pass.cpp
index 2c769d87cf3..30dbd9ea11f 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_exact.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_exact.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::is_exact == expected, "is_exact test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, true>();
     test<char, true>();
@@ -53,4 +53,6 @@ int main()
     test<float, false>();
     test<double, false>();
     test<long double, false>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_iec559.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_iec559.pass.cpp
index c7edf178dc2..215407d74b3 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_iec559.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_iec559.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::is_iec559 == expected, "is_iec559 test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, false>();
     test<char, false>();
@@ -57,4 +57,6 @@ int main()
 #else
     test<long double, true>();
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_integer.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_integer.pass.cpp
index 80a45fa29f8..66ce0cb2bad 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_integer.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_integer.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::is_integer == expected, "is_integer test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, true>();
     test<char, true>();
@@ -53,4 +53,6 @@ int main()
     test<float, false>();
     test<double, false>();
     test<long double, false>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_modulo.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_modulo.pass.cpp
index c364fd01bd1..2eb2c4ba494 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_modulo.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_modulo.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::is_modulo == expected, "is_modulo test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, false>();
 //    test<char, false>(); // don't know
@@ -53,4 +53,6 @@ int main()
     test<float, false>();
     test<double, false>();
     test<long double, false>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_signed.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_signed.pass.cpp
index 08dc5eb772f..818ad4db9f4 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_signed.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/is_signed.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::is_signed == expected, "is_signed test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, false>();
     test<char, char(-1) < char(0)>();
@@ -53,4 +53,6 @@ int main()
     test<float, true>();
     test<double, true>();
     test<long double, true>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/lowest.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/lowest.pass.cpp
index bb6ae168e72..adf147c7069 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/lowest.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/lowest.pass.cpp
@@ -32,7 +32,7 @@ test(T expected)
     assert(std::numeric_limits<const volatile T>::is_bounded);
 }
 
-int main()
+int main(int, char**)
 {
     test<bool>(false);
     test<char>(CHAR_MIN);
@@ -61,4 +61,6 @@ int main()
     test<float>(-FLT_MAX);
     test<double>(-DBL_MAX);
     test<long double>(-LDBL_MAX);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max.pass.cpp
index 0bf7237ad9e..91f353ab5e2 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max.pass.cpp
@@ -32,7 +32,7 @@ test(T expected)
     assert(std::numeric_limits<const volatile T>::is_bounded);
 }
 
-int main()
+int main(int, char**)
 {
     test<bool>(true);
     test<char>(CHAR_MAX);
@@ -61,4 +61,6 @@ int main()
     test<float>(FLT_MAX);
     test<double>(DBL_MAX);
     test<long double>(LDBL_MAX);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max_digits10.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max_digits10.pass.cpp
index 4b871487527..3cf7d509695 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max_digits10.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max_digits10.pass.cpp
@@ -25,7 +25,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::max_digits10 == expected, "max_digits10 test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, 0>();
     test<char, 0>();
@@ -54,4 +54,6 @@ int main()
     test<float, 2+(FLT_MANT_DIG * 30103)/100000>();
     test<double, 2+(DBL_MANT_DIG * 30103)/100000>();
     test<long double, 2+(LDBL_MANT_DIG * 30103)/100000>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max_exponent.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max_exponent.pass.cpp
index 7ce1ac9d744..325ad797977 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max_exponent.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max_exponent.pass.cpp
@@ -25,7 +25,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::max_exponent == expected, "max_exponent test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, 0>();
     test<char, 0>();
@@ -54,4 +54,6 @@ int main()
     test<float, FLT_MAX_EXP>();
     test<double, DBL_MAX_EXP>();
     test<long double, LDBL_MAX_EXP>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max_exponent10.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max_exponent10.pass.cpp
index e2bbdde1096..e1a4ffe29be 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max_exponent10.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/max_exponent10.pass.cpp
@@ -25,7 +25,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::max_exponent10 == expected, "max_exponent10 test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, 0>();
     test<char, 0>();
@@ -54,4 +54,6 @@ int main()
     test<float, FLT_MAX_10_EXP>();
     test<double, DBL_MAX_10_EXP>();
     test<long double, LDBL_MAX_10_EXP>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/min.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/min.pass.cpp
index 66ddaa474e9..0d2cb3c1bc3 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/min.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/min.pass.cpp
@@ -32,7 +32,7 @@ test(T expected)
     assert(std::numeric_limits<const volatile T>::is_bounded || !std::numeric_limits<const volatile T>::is_signed);
 }
 
-int main()
+int main(int, char**)
 {
     test<bool>(false);
     test<char>(CHAR_MIN);
@@ -61,4 +61,6 @@ int main()
     test<float>(FLT_MIN);
     test<double>(DBL_MIN);
     test<long double>(LDBL_MIN);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/min_exponent.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/min_exponent.pass.cpp
index 8fb4f09f6a7..5708d8a20f5 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/min_exponent.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/min_exponent.pass.cpp
@@ -25,7 +25,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::min_exponent == expected, "min_exponent test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, 0>();
     test<char, 0>();
@@ -54,4 +54,6 @@ int main()
     test<float, FLT_MIN_EXP>();
     test<double, DBL_MIN_EXP>();
     test<long double, LDBL_MIN_EXP>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/min_exponent10.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/min_exponent10.pass.cpp
index 812dd53bbe0..f598d42fa8e 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/min_exponent10.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/min_exponent10.pass.cpp
@@ -25,7 +25,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::min_exponent10 == expected, "min_exponent10 test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, 0>();
     test<char, 0>();
@@ -54,4 +54,6 @@ int main()
     test<float, FLT_MIN_10_EXP>();
     test<double, DBL_MIN_10_EXP>();
     test<long double, LDBL_MIN_10_EXP>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/quiet_NaN.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/quiet_NaN.pass.cpp
index 852cf86a13a..f4ea61f23dc 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/quiet_NaN.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/quiet_NaN.pass.cpp
@@ -45,7 +45,7 @@ test()
     test_imp<T>(std::is_floating_point<T>());
 }
 
-int main()
+int main(int, char**)
 {
     test<bool>();
     test<char>();
@@ -74,4 +74,6 @@ int main()
     test<float>();
     test<double>();
     test<long double>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/radix.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/radix.pass.cpp
index 8c9e48a2d71..8f13768b0bd 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/radix.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/radix.pass.cpp
@@ -25,7 +25,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::radix == expected, "radix test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, 2>();
     test<char, 2>();
@@ -54,4 +54,6 @@ int main()
     test<float, FLT_RADIX>();
     test<double, FLT_RADIX>();
     test<long double, FLT_RADIX>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/round_error.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/round_error.pass.cpp
index f2d962df4b6..ddc4490db0b 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/round_error.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/round_error.pass.cpp
@@ -26,7 +26,7 @@ test(T expected)
     assert(std::numeric_limits<const volatile T>::round_error() == expected);
 }
 
-int main()
+int main(int, char**)
 {
     test<bool>(false);
     test<char>(0);
@@ -55,4 +55,6 @@ int main()
     test<float>(0.5);
     test<double>(0.5);
     test<long double>(0.5);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/round_style.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/round_style.pass.cpp
index 43e962961a6..81d4ce6ebcf 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/round_style.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/round_style.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::round_style == expected, "round_style test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, std::round_toward_zero>();
     test<char, std::round_toward_zero>();
@@ -53,4 +53,6 @@ int main()
     test<float, std::round_to_nearest>();
     test<double, std::round_to_nearest>();
     test<long double, std::round_to_nearest>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/signaling_NaN.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/signaling_NaN.pass.cpp
index 312f6971498..70138671095 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/signaling_NaN.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/signaling_NaN.pass.cpp
@@ -45,7 +45,7 @@ test()
     test_imp<T>(std::is_floating_point<T>());
 }
 
-int main()
+int main(int, char**)
 {
     test<bool>();
     test<char>();
@@ -74,4 +74,6 @@ int main()
     test<float>();
     test<double>();
     test<long double>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/tinyness_before.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/tinyness_before.pass.cpp
index 3e0ad694b44..c150e5f23d0 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/tinyness_before.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/tinyness_before.pass.cpp
@@ -24,7 +24,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::tinyness_before == expected, "tinyness_before test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, false>();
     test<char, false>();
@@ -53,4 +53,6 @@ int main()
     test<float, false>();
     test<double, false>();
     test<long double, false>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/traps.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/traps.pass.cpp
index e71432b18a1..e7ea388192d 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/traps.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits.members/traps.pass.cpp
@@ -31,7 +31,7 @@ test()
     static_assert(std::numeric_limits<const volatile T>::traps == expected, "traps test 4");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool, false>();
     test<char, integral_types_trap>();
@@ -60,4 +60,6 @@ int main()
     test<float, false>();
     test<double, false>();
     test<long double, false>();
+
+  return 0;
 }