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

210 files changed, 546 insertions, 210 deletions

diff --git a/libcxx/test/std/language.support/cmp/cmp.common/common_comparison_category.pass.cpp b/libcxx/test/std/language.support/cmp/cmp.common/common_comparison_category.pass.cpp
index 4c999637ffb..218291b6b49 100644
--- a/libcxx/test/std/language.support/cmp/cmp.common/common_comparison_category.pass.cpp
+++ b/libcxx/test/std/language.support/cmp/cmp.common/common_comparison_category.pass.cpp
@@ -33,7 +33,7 @@ void test_cat() {
 
 // [class.spaceship]p4: The 'common comparison type' U of a possibly-empty list
 //   of 'n' types T0, T1, ..., TN, is defined as follows:
-int main() {
+int main(int, char**) {
   using WE = std::weak_equality;
   using SE = std::strong_equality;
   using PO = std::partial_ordering;
@@ -89,4 +89,6 @@ int main() {
     test_cat<SO, SO>();
     test_cat<SO, SO, SO>();
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/cmp/cmp.partialord/partialord.pass.cpp b/libcxx/test/std/language.support/cmp/cmp.partialord/partialord.pass.cpp
index 6c51b7a208d..f2e673db696 100644
--- a/libcxx/test/std/language.support/cmp/cmp.partialord/partialord.pass.cpp
+++ b/libcxx/test/std/language.support/cmp/cmp.partialord/partialord.pass.cpp
@@ -155,9 +155,11 @@ constexpr bool test_constexpr() {
   return true;
 }
 
-int main() {
+int main(int, char**) {
   test_static_members();
   test_signatures();
   static_assert(test_conversion(), "conversion test failed");
   static_assert(test_constexpr(), "constexpr test failed");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/cmp/cmp.strongeq/cmp.strongeq.pass.cpp b/libcxx/test/std/language.support/cmp/cmp.strongeq/cmp.strongeq.pass.cpp
index e34cadc55ce..a5af910a5e0 100644
--- a/libcxx/test/std/language.support/cmp/cmp.strongeq/cmp.strongeq.pass.cpp
+++ b/libcxx/test/std/language.support/cmp/cmp.strongeq/cmp.strongeq.pass.cpp
@@ -87,9 +87,11 @@ constexpr bool test_constexpr() {
   return true;
 }
 
-int main() {
+int main(int, char**) {
   test_static_members();
   test_signatures();
   test_conversion();
   static_assert(test_constexpr(), "constexpr test failed");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/cmp/cmp.strongord/strongord.pass.cpp b/libcxx/test/std/language.support/cmp/cmp.strongord/strongord.pass.cpp
index 4b75e5d51ef..a31fd34d4f1 100644
--- a/libcxx/test/std/language.support/cmp/cmp.strongord/strongord.pass.cpp
+++ b/libcxx/test/std/language.support/cmp/cmp.strongord/strongord.pass.cpp
@@ -203,9 +203,11 @@ constexpr bool test_constexpr() {
   return true;
 }
 
-int main() {
+int main(int, char**) {
   test_static_members();
   test_signatures();
   static_assert(test_conversion(), "conversion test failed");
   static_assert(test_constexpr(), "constexpr test failed");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/cmp/cmp.weakeq/cmp.weakeq.pass.cpp b/libcxx/test/std/language.support/cmp/cmp.weakeq/cmp.weakeq.pass.cpp
index dae2f214717..367aac6bebe 100644
--- a/libcxx/test/std/language.support/cmp/cmp.weakeq/cmp.weakeq.pass.cpp
+++ b/libcxx/test/std/language.support/cmp/cmp.weakeq/cmp.weakeq.pass.cpp
@@ -62,8 +62,10 @@ constexpr bool test_constexpr() {
   return true;
 }
 
-int main() {
+int main(int, char**) {
   test_static_members();
   test_signatures();
   static_assert(test_constexpr(), "constexpr test failed");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/cmp/cmp.weakord/weakord.pass.cpp b/libcxx/test/std/language.support/cmp/cmp.weakord/weakord.pass.cpp
index 6e9e7d44106..ada8d240b6d 100644
--- a/libcxx/test/std/language.support/cmp/cmp.weakord/weakord.pass.cpp
+++ b/libcxx/test/std/language.support/cmp/cmp.weakord/weakord.pass.cpp
@@ -160,9 +160,11 @@ constexpr bool test_constexpr() {
   return true;
 }
 
-int main() {
+int main(int, char**) {
   test_static_members();
   test_signatures();
   static_assert(test_conversion(), "conversion test failed");
   static_assert(test_constexpr(), "constexpr test failed");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/cstdint/cstdint.syn/cstdint.pass.cpp b/libcxx/test/std/language.support/cstdint/cstdint.syn/cstdint.pass.cpp
index 6f46342da94..ec4afd7f69d 100644
--- a/libcxx/test/std/language.support/cstdint/cstdint.syn/cstdint.pass.cpp
+++ b/libcxx/test/std/language.support/cstdint/cstdint.syn/cstdint.pass.cpp
@@ -18,7 +18,7 @@
 #include <limits>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     // typedef std::int8_t
     static_assert(sizeof(std::int8_t)*CHAR_BIT == 8,
@@ -288,4 +288,6 @@ int main()
 #ifndef UINTMAX_C
 #error UINTMAX_C not defined
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/nothing_to_do.pass.cpp b/libcxx/test/std/language.support/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/language.support/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/language.support/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/align_val_t.pass.cpp b/libcxx/test/std/language.support/support.dynamic/align_val_t.pass.cpp
index 1b0b4c00baa..6e65518233a 100644
--- a/libcxx/test/std/language.support/support.dynamic/align_val_t.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/align_val_t.pass.cpp
@@ -14,7 +14,7 @@
 
 #include "test_macros.h"
 
-int main() {
+int main(int, char**) {
   {
     static_assert(std::is_enum<std::align_val_t>::value, "");
     static_assert(std::is_same<std::underlying_type<std::align_val_t>::type, std::size_t>::value, "");
@@ -30,4 +30,6 @@ int main() {
     static_assert(b == std::align_val_t(32), "");
     static_assert(static_cast<std::size_t>(c) == (std::size_t)-1, "");
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/alloc.errors/bad.alloc/bad_alloc.pass.cpp b/libcxx/test/std/language.support/support.dynamic/alloc.errors/bad.alloc/bad_alloc.pass.cpp
index 713e66245c0..f0b2bd21fec 100644
--- a/libcxx/test/std/language.support/support.dynamic/alloc.errors/bad.alloc/bad_alloc.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/alloc.errors/bad.alloc/bad_alloc.pass.cpp
@@ -12,7 +12,7 @@
 #include <type_traits>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::exception, std::bad_alloc>::value),
                  "std::is_base_of<std::exception, std::bad_alloc>::value");
@@ -23,4 +23,6 @@ int main()
     b2 = b;
     const char* w = b2.what();
     assert(w);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/alloc.errors/new.badlength/bad_array_new_length.pass.cpp b/libcxx/test/std/language.support/support.dynamic/alloc.errors/new.badlength/bad_array_new_length.pass.cpp
index d2fefdd1b94..35fd1304125 100644
--- a/libcxx/test/std/language.support/support.dynamic/alloc.errors/new.badlength/bad_array_new_length.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/alloc.errors/new.badlength/bad_array_new_length.pass.cpp
@@ -12,7 +12,7 @@
 #include <type_traits>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::bad_alloc, std::bad_array_new_length>::value),
                   "std::is_base_of<std::bad_alloc, std::bad_array_new_length>::value");
@@ -23,4 +23,6 @@ int main()
     b2 = b;
     const char* w = b2.what();
     assert(w);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/alloc.errors/new.handler/new_handler.pass.cpp b/libcxx/test/std/language.support/support.dynamic/alloc.errors/new.handler/new_handler.pass.cpp
index f5681d8d92f..b69fe15232c 100644
--- a/libcxx/test/std/language.support/support.dynamic/alloc.errors/new.handler/new_handler.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/alloc.errors/new.handler/new_handler.pass.cpp
@@ -14,9 +14,11 @@
 
 void f() {}
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_same<std::new_handler, void(*)()>::value), "");
     std::new_handler p = f;
     assert(p == &f);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/alloc.errors/nothing_to_do.pass.cpp b/libcxx/test/std/language.support/support.dynamic/alloc.errors/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/language.support/support.dynamic/alloc.errors/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/alloc.errors/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/alloc.errors/set.new.handler/get_new_handler.pass.cpp b/libcxx/test/std/language.support/support.dynamic/alloc.errors/set.new.handler/get_new_handler.pass.cpp
index 922ab9db49c..a9ed3b0cf36 100644
--- a/libcxx/test/std/language.support/support.dynamic/alloc.errors/set.new.handler/get_new_handler.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/alloc.errors/set.new.handler/get_new_handler.pass.cpp
@@ -14,11 +14,13 @@
 void f1() {}
 void f2() {}
 
-int main()
+int main(int, char**)
 {
     assert(std::get_new_handler() == 0);
     std::set_new_handler(f1);
     assert(std::get_new_handler() == f1);
     std::set_new_handler(f2);
     assert(std::get_new_handler() == f2);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/alloc.errors/set.new.handler/set_new_handler.pass.cpp b/libcxx/test/std/language.support/support.dynamic/alloc.errors/set.new.handler/set_new_handler.pass.cpp
index 37c477f1312..cff382b0ee3 100644
--- a/libcxx/test/std/language.support/support.dynamic/alloc.errors/set.new.handler/set_new_handler.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/alloc.errors/set.new.handler/set_new_handler.pass.cpp
@@ -14,8 +14,10 @@
 void f1() {}
 void f2() {}
 
-int main()
+int main(int, char**)
 {
     assert(std::set_new_handler(f1) == 0);
     assert(std::set_new_handler(f2) == f1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/delete_align_val_t_replace.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/delete_align_val_t_replace.pass.cpp
index de09a75557a..0a5265861b6 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/delete_align_val_t_replace.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/delete_align_val_t_replace.pass.cpp
@@ -83,7 +83,7 @@ void operator delete [] (void* p, std::align_val_t) TEST_NOEXCEPT
 struct alignas(OverAligned) A {};
 struct alignas(std::max_align_t) B {};
 
-int main()
+int main(int, char**)
 {
     reset();
     {
@@ -113,4 +113,6 @@ int main()
         assert(0 == unsized_delete_nothrow_called);
         assert(1 == aligned_delete_called);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t.pass.cpp
index bd99495e573..e303c820847 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t.pass.cpp
@@ -90,7 +90,7 @@ void test_throw_max_size() {
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
         A* ap = new A[2];
@@ -103,4 +103,6 @@ int main()
     {
         test_throw_max_size();
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_nothrow.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_nothrow.pass.cpp
index a8367876903..ed7a53743f0 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_nothrow.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_nothrow.pass.cpp
@@ -92,7 +92,7 @@ void test_max_alloc() {
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
         A* ap = new(std::nothrow) A[3];
@@ -105,4 +105,6 @@ int main()
     {
         test_max_alloc();
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_nothrow_replace.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_nothrow_replace.pass.cpp
index 5fbcc5ce753..49aa2bce3ea 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_nothrow_replace.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_nothrow_replace.pass.cpp
@@ -86,7 +86,7 @@ void  operator delete[](void* p, std::align_val_t a) TEST_NOEXCEPT
     --new_called;
 }
 
-int main()
+int main(int, char**)
 {
     {
         A* ap = new (std::nothrow) A[2];
@@ -106,4 +106,6 @@ int main()
         assert(!new_called);
         assert(!B_constructed);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_replace.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_replace.pass.cpp
index 40ba48dec53..cb9a2ef7f6c 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_replace.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_align_val_t_replace.pass.cpp
@@ -66,7 +66,7 @@ void  operator delete[](void* p, std::align_val_t) TEST_NOEXCEPT
 }
 
 
-int main()
+int main(int, char**)
 {
     {
         A* ap = new A[3];
@@ -85,4 +85,6 @@ int main()
         delete [] bp;
         assert(!new_called);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array.pass.cpp
index 8365b053c5d..55dc5c75334 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array.pass.cpp
@@ -34,7 +34,7 @@ struct A
     ~A() {--A_constructed;}
 };
 
-int main()
+int main(int, char**)
 {
 #ifndef TEST_HAS_NO_EXCEPTIONS
     std::set_new_handler(my_new_handler);
@@ -60,4 +60,6 @@ int main()
     delete [] ap;
     DoNotOptimize(ap);
     assert(A_constructed == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_nothrow.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_nothrow.pass.cpp
index 3effc7ea3ec..b4d8aa34986 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_nothrow.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_nothrow.pass.cpp
@@ -34,7 +34,7 @@ struct A
     ~A() {--A_constructed;}
 };
 
-int main()
+int main(int, char**)
 {
     std::set_new_handler(my_new_handler);
 #ifndef TEST_HAS_NO_EXCEPTIONS
@@ -59,4 +59,6 @@ int main()
     delete [] ap;
     DoNotOptimize(ap);
     assert(A_constructed == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_nothrow_replace.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_nothrow_replace.pass.cpp
index a28f7f4f153..4d90aa9a3fe 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_nothrow_replace.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_nothrow_replace.pass.cpp
@@ -43,7 +43,7 @@ struct A
     ~A() {--A_constructed;}
 };
 
-int main()
+int main(int, char**)
 {
     A *ap = new (std::nothrow) A[3];
     DoNotOptimize(ap);
@@ -54,4 +54,6 @@ int main()
     DoNotOptimize(ap);
     assert(A_constructed == 0);
     assert(!new_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_replace.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_replace.pass.cpp
index 4ea28241c07..e705fc3b499 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_replace.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_array_replace.pass.cpp
@@ -44,7 +44,7 @@ struct A
     ~A() {--A_constructed;}
 };
 
-int main()
+int main(int, char**)
 {
     A *ap = new A[3];
     DoNotOptimize(ap);
@@ -55,4 +55,6 @@ int main()
     DoNotOptimize(ap);
     assert(A_constructed == 0);
     assert(new_called == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size.sh.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size.sh.cpp
index 482a27e9cf6..a04ceb6ad42 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size.sh.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size.sh.cpp
@@ -19,7 +19,9 @@
 
 #include <new>
 
-int main ()
+int main(int, char**)
 {
     ::operator new[](4);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size_align.sh.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size_align.sh.cpp
index 6183c0c2ce3..e2a61591ad2 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size_align.sh.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size_align.sh.cpp
@@ -19,7 +19,9 @@
 
 #include <new>
 
-int main ()
+int main(int, char**)
 {
     ::operator new[](4, std::align_val_t{4});  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size_align_nothrow.sh.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size_align_nothrow.sh.cpp
index 1f39219090b..5ad81863d4d 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size_align_nothrow.sh.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size_align_nothrow.sh.cpp
@@ -19,7 +19,9 @@
 
 #include <new>
 
-int main ()
+int main(int, char**)
 {
     ::operator new[](4, std::align_val_t{4}, std::nothrow);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size_nothrow.sh.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size_nothrow.sh.cpp
index 39de421c283..53af2c764c0 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size_nothrow.sh.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/new_size_nothrow.sh.cpp
@@ -19,7 +19,9 @@
 
 #include <new>
 
-int main ()
+int main(int, char**)
 {
     ::operator new[](4, std::nothrow);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array11.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array11.pass.cpp
index 686ef66bab8..e1a545cc983 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array11.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array11.pass.cpp
@@ -54,7 +54,7 @@ void operator delete[](void* p, std::size_t) TEST_NOEXCEPT
 //   selected.
 struct A { ~A() {} };
 
-int main()
+int main(int, char**)
 {
 
     A* x = new A[3];
@@ -66,4 +66,6 @@ int main()
     assert(1 == unsized_delete_called);
     assert(0 == sized_delete_called);
     assert(0 == unsized_delete_nothrow_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array14.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array14.pass.cpp
index 773a9b9928d..d69c28be72b 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array14.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array14.pass.cpp
@@ -59,7 +59,7 @@ void operator delete[](void* p, std::size_t) TEST_NOEXCEPT
 //   selected.
 struct A { ~A() {} };
 
-int main()
+int main(int, char**)
 {
     A* x = new A[3];
     assert(0 == unsized_delete_called);
@@ -70,4 +70,6 @@ int main()
     assert(0 == unsized_delete_called);
     assert(0 == unsized_delete_nothrow_called);
     assert(1 == sized_delete_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array_calls_unsized_delete_array.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array_calls_unsized_delete_array.pass.cpp
index 2d845e6010d..026250daeee 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array_calls_unsized_delete_array.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array_calls_unsized_delete_array.pass.cpp
@@ -45,7 +45,7 @@ void operator delete[](void* p, const std::nothrow_t&) TEST_NOEXCEPT
 //   selected.
 struct A { ~A() {} };
 
-int main()
+int main(int, char**)
 {
     A *x = new A[3];
     DoNotOptimize(x);
@@ -56,4 +56,6 @@ int main()
     DoNotOptimize(x);
     assert(1 == delete_called);
     assert(0 == delete_nothrow_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array_fsizeddeallocation.sh.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array_fsizeddeallocation.sh.cpp
index a077fb7cec6..41739c0ccdc 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array_fsizeddeallocation.sh.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.array/sized_delete_array_fsizeddeallocation.sh.cpp
@@ -73,7 +73,7 @@ void operator delete[](void* p, std::size_t) TEST_NOEXCEPT
 //   selected.
 struct A { ~A() {} };
 
-int main()
+int main(int, char**)
 {
     A* x = new A[3];
     assert(0 == unsized_delete_called);
@@ -84,4 +84,6 @@ int main()
     assert(0 == unsized_delete_called);
     assert(0 == unsized_delete_nothrow_called);
     assert(1 == sized_delete_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.dataraces/not_testable.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.dataraces/not_testable.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.dataraces/not_testable.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.dataraces/not_testable.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new.pass.cpp
index 3cd5e12458f..8256b93185d 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new.pass.cpp
@@ -19,11 +19,13 @@ struct A
     ~A() {--A_constructed;}
 };
 
-int main()
+int main(int, char**)
 {
     char buf[sizeof(A)];
 
     A* ap = new(buf) A;
     assert((char*)ap == buf);
     assert(A_constructed == 1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new_array.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new_array.pass.cpp
index 671a3cc050f..8a78df6bffb 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new_array.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new_array.pass.cpp
@@ -19,7 +19,7 @@ struct A
     ~A() {--A_constructed;}
 };
 
-int main()
+int main(int, char**)
 {
     const std::size_t Size = 3;
     // placement new might require additional space.
@@ -30,4 +30,6 @@ int main()
     assert((char*)ap >= buf);
     assert((char*)ap < (buf + ExtraSize));
     assert(A_constructed == Size);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new_array_ptr.fail.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new_array_ptr.fail.cpp
index b7b17e196e8..4cba717dba8 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new_array_ptr.fail.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new_array_ptr.fail.cpp
@@ -18,8 +18,10 @@
 
 #include "test_macros.h"
 
-int main ()
+int main(int, char**)
 {
     char buffer[100];
     ::operator new[](4, buffer);  // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new_ptr.fail.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new_ptr.fail.cpp
index 7b5eb19d92c..05a9b244c1e 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new_ptr.fail.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.placement/new_ptr.fail.cpp
@@ -18,8 +18,10 @@
 
 #include "test_macros.h"
 
-int main ()
+int main(int, char**)
 {
     char buffer[100];
     ::operator new(4, buffer);  // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/delete_align_val_t_replace.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/delete_align_val_t_replace.pass.cpp
index 63e797480b1..22abcba0522 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/delete_align_val_t_replace.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/delete_align_val_t_replace.pass.cpp
@@ -82,7 +82,7 @@ void operator delete(void* p, std::align_val_t) TEST_NOEXCEPT
 struct alignas(OverAligned) A {};
 struct alignas(std::max_align_t) B {};
 
-int main()
+int main(int, char**)
 {
     reset();
     {
@@ -112,4 +112,6 @@ int main()
         assert(0 == unsized_delete_nothrow_called);
         assert(1 == aligned_delete_called);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new.pass.cpp
index 3c73738d6fd..448da171790 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new.pass.cpp
@@ -34,7 +34,7 @@ struct A
     ~A() {A_constructed = false;}
 };
 
-int main()
+int main(int, char**)
 {
 #ifndef TEST_HAS_NO_EXCEPTIONS
     std::set_new_handler(my_new_handler);
@@ -58,4 +58,6 @@ int main()
     assert(A_constructed);
     delete ap;
     assert(!A_constructed);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t.pass.cpp
index d0d4b98aee4..0d96db5de48 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t.pass.cpp
@@ -90,7 +90,7 @@ void test_throw_max_size() {
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
         A* ap = new A;
@@ -103,4 +103,6 @@ int main()
     {
         test_throw_max_size();
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_nothrow.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_nothrow.pass.cpp
index d0990c0586b..4b621f78a72 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_nothrow.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_nothrow.pass.cpp
@@ -92,7 +92,7 @@ void test_max_alloc() {
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
         A* ap = new(std::nothrow) A;
@@ -105,4 +105,6 @@ int main()
     {
         test_max_alloc();
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_nothrow_replace.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_nothrow_replace.pass.cpp
index fa8dc13cf64..892eac20582 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_nothrow_replace.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_nothrow_replace.pass.cpp
@@ -88,7 +88,7 @@ void  operator delete(void* p, std::align_val_t a) TEST_NOEXCEPT
 }
 
 
-int main()
+int main(int, char**)
 {
     {
         A* ap = new (std::nothrow) A;
@@ -108,4 +108,6 @@ int main()
         assert(!new_called);
         assert(!B_constructed);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_replace.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_replace.pass.cpp
index d37ca28f03b..32c27d5899e 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_replace.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_align_val_t_replace.pass.cpp
@@ -66,7 +66,7 @@ void  operator delete(void* p, std::align_val_t) TEST_NOEXCEPT
 }
 
 
-int main()
+int main(int, char**)
 {
     {
         A* ap = new A;
@@ -85,4 +85,6 @@ int main()
         delete bp;
         assert(!new_called);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_nothrow.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_nothrow.pass.cpp
index 6d391645f11..dfdf7d77e80 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_nothrow.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_nothrow.pass.cpp
@@ -34,7 +34,7 @@ struct A
     ~A() {A_constructed = false;}
 };
 
-int main()
+int main(int, char**)
 {
     std::set_new_handler(my_new_handler);
 #ifndef TEST_HAS_NO_EXCEPTIONS
@@ -56,4 +56,6 @@ int main()
     assert(A_constructed);
     delete ap;
     assert(!A_constructed);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_nothrow_replace.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_nothrow_replace.pass.cpp
index b4217525fe6..1f186d8b3d1 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_nothrow_replace.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_nothrow_replace.pass.cpp
@@ -43,7 +43,7 @@ struct A
     ~A() {A_constructed = false;}
 };
 
-int main()
+int main(int, char**)
 {
     A *ap = new (std::nothrow) A;
     DoNotOptimize(ap);
@@ -54,4 +54,6 @@ int main()
     DoNotOptimize(ap);
     assert(!A_constructed);
     assert(!new_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_replace.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_replace.pass.cpp
index 300843b2fa0..4854c2fb776 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_replace.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_replace.pass.cpp
@@ -42,7 +42,7 @@ struct A
     ~A() {A_constructed = false;}
 };
 
-int main()
+int main(int, char**)
 {
     A *ap = new A;
     DoNotOptimize(ap);
@@ -53,4 +53,6 @@ int main()
     DoNotOptimize(ap);
     assert(!A_constructed);
     assert(!new_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size.fail.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size.fail.cpp
index 5042a8d1e49..4769933d399 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size.fail.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size.fail.cpp
@@ -18,7 +18,9 @@
 
 #include "test_macros.h"
 
-int main ()
+int main(int, char**)
 {
     ::operator new(4);  // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size_align.sh.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size_align.sh.cpp
index e22ea0fdd20..a0d99c76d07 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size_align.sh.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size_align.sh.cpp
@@ -19,7 +19,9 @@
 
 #include <new>
 
-int main ()
+int main(int, char**)
 {
     ::operator new(4, std::align_val_t{4});  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size_align_nothrow.sh.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size_align_nothrow.sh.cpp
index 617eeae3cfd..54b25ac5589 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size_align_nothrow.sh.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size_align_nothrow.sh.cpp
@@ -19,7 +19,9 @@
 
 #include <new>
 
-int main ()
+int main(int, char**)
 {
     ::operator new(4, std::align_val_t{4}, std::nothrow);  // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size_nothrow.fail.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size_nothrow.fail.cpp
index dd51ad54af9..a0bfa8b7f92 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size_nothrow.fail.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/new_size_nothrow.fail.cpp
@@ -18,7 +18,9 @@
 
 #include "test_macros.h"
 
-int main ()
+int main(int, char**)
 {
     ::operator new(4, std::nothrow);  // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete11.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete11.pass.cpp
index 779d7b2acfe..69f8bce2767 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete11.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete11.pass.cpp
@@ -43,7 +43,7 @@ void operator delete(void* p, std::size_t) TEST_NOEXCEPT
     std::free(p);
 }
 
-int main()
+int main(int, char**)
 {
     int *x = new int(42);
     DoNotOptimize(x);
@@ -56,4 +56,6 @@ int main()
     assert(1 == unsized_delete_called);
     assert(0 == sized_delete_called);
     assert(0 == unsized_delete_nothrow_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete14.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete14.pass.cpp
index bed5cc2323a..deb17d1ae74 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete14.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete14.pass.cpp
@@ -48,7 +48,7 @@ void operator delete(void* p, std::size_t) TEST_NOEXCEPT
     std::free(p);
 }
 
-int main()
+int main(int, char**)
 {
     int *x = new int(42);
     DoNotOptimize(x);
@@ -61,4 +61,6 @@ int main()
     assert(0 == unsized_delete_called);
     assert(1 == sized_delete_called);
     assert(0 == unsized_delete_nothrow_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete_calls_unsized_delete.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete_calls_unsized_delete.pass.cpp
index 9c54750bde1..fbc9cf070bc 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete_calls_unsized_delete.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete_calls_unsized_delete.pass.cpp
@@ -34,7 +34,7 @@ void operator delete(void* p, const std::nothrow_t&) TEST_NOEXCEPT
     std::free(p);
 }
 
-int main()
+int main(int, char**)
 {
     int *x = new int(42);
     DoNotOptimize(x);
@@ -45,4 +45,6 @@ int main()
     DoNotOptimize(x);
     assert(1 == delete_called);
     assert(0 == delete_nothrow_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete_fsizeddeallocation.sh.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete_fsizeddeallocation.sh.cpp
index be208b43165..3d62040cbe8 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete_fsizeddeallocation.sh.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/new.delete.single/sized_delete_fsizeddeallocation.sh.cpp
@@ -61,7 +61,7 @@ void operator delete(void* p, std::size_t) TEST_NOEXCEPT
     std::free(p);
 }
 
-int main()
+int main(int, char**)
 {
     int *x = new int(42);
     DoNotOptimize(x);
@@ -74,4 +74,6 @@ int main()
     assert(1 == sized_delete_called);
     assert(0 == unsized_delete_called);
     assert(0 == unsized_delete_nothrow_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/new.delete/nothing_to_do.pass.cpp b/libcxx/test/std/language.support/support.dynamic/new.delete/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/language.support/support.dynamic/new.delete/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/new.delete/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/ptr.launder/launder.nodiscard.fail.cpp b/libcxx/test/std/language.support/support.dynamic/ptr.launder/launder.nodiscard.fail.cpp
index 3f105410bad..e7252395d35 100644
--- a/libcxx/test/std/language.support/support.dynamic/ptr.launder/launder.nodiscard.fail.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/ptr.launder/launder.nodiscard.fail.cpp
@@ -19,8 +19,10 @@
 
 #include "test_macros.h"
 
-int main ()
+int main(int, char**)
 {
     int *p = nullptr;
     std::launder(p);  // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/ptr.launder/launder.pass.cpp b/libcxx/test/std/language.support/support.dynamic/ptr.launder/launder.pass.cpp
index c3d2271834f..f9d4da37146 100644
--- a/libcxx/test/std/language.support/support.dynamic/ptr.launder/launder.pass.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/ptr.launder/launder.pass.cpp
@@ -20,7 +20,7 @@
 constexpr int gi = 5;
 constexpr float gf = 8.f;
 
-int main() {
+int main(int, char**) {
     static_assert(std::launder(&gi) == &gi, "" );
     static_assert(std::launder(&gf) == &gf, "" );
 
@@ -31,4 +31,6 @@ int main() {
 
     assert(std::launder(i) == i);
     assert(std::launder(f) == f);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.dynamic/ptr.launder/launder.types.fail.cpp b/libcxx/test/std/language.support/support.dynamic/ptr.launder/launder.types.fail.cpp
index f8fd12f1cda..d97d00194e2 100644
--- a/libcxx/test/std/language.support/support.dynamic/ptr.launder/launder.types.fail.cpp
+++ b/libcxx/test/std/language.support/support.dynamic/ptr.launder/launder.types.fail.cpp
@@ -21,7 +21,7 @@
 
 void foo() {}
 
-int main ()
+int main(int, char**)
 {
     void *p = nullptr;
     (void) std::launder((               void *) nullptr);
@@ -32,4 +32,6 @@ int main ()
 
     (void) std::launder(foo);                              // expected-error-re@new:* 1 {{static_assert failed{{.*}} "can't launder functions"}}
     // expected-error@new:* 0-1 {{function pointer argument to '__builtin_launder' is not allowed}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/bad.exception/bad_exception.pass.cpp b/libcxx/test/std/language.support/support.exception/bad.exception/bad_exception.pass.cpp
index c4e1cc7a1ab..e5f4fbe6dcf 100644
--- a/libcxx/test/std/language.support/support.exception/bad.exception/bad_exception.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/bad.exception/bad_exception.pass.cpp
@@ -12,7 +12,7 @@
 #include <type_traits>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::exception, std::bad_exception>::value),
                  "std::is_base_of<std::exception, std::bad_exception>::value");
@@ -23,4 +23,6 @@ int main()
     b2 = b;
     const char* w = b2.what();
     assert(w);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/except.nested/assign.pass.cpp b/libcxx/test/std/language.support/support.exception/except.nested/assign.pass.cpp
index c03f4bbfd4f..972649579b1 100644
--- a/libcxx/test/std/language.support/support.exception/except.nested/assign.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/except.nested/assign.pass.cpp
@@ -26,7 +26,7 @@ public:
     friend bool operator==(const A& x, const A& y) {return x.data_ == y.data_;}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::nested_exception e0;
@@ -59,4 +59,6 @@ int main()
         }
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/except.nested/ctor_copy.pass.cpp b/libcxx/test/std/language.support/support.exception/except.nested/ctor_copy.pass.cpp
index cc8c9985622..9d65f5fb22b 100644
--- a/libcxx/test/std/language.support/support.exception/except.nested/ctor_copy.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/except.nested/ctor_copy.pass.cpp
@@ -26,7 +26,7 @@ public:
     friend bool operator==(const A& x, const A& y) {return x.data_ == y.data_;}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::nested_exception e0;
@@ -57,4 +57,6 @@ int main()
         }
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/except.nested/ctor_default.pass.cpp b/libcxx/test/std/language.support/support.exception/except.nested/ctor_default.pass.cpp
index 5aa762cf7ca..a96c3d015a1 100644
--- a/libcxx/test/std/language.support/support.exception/except.nested/ctor_default.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/except.nested/ctor_default.pass.cpp
@@ -26,7 +26,7 @@ public:
     friend bool operator==(const A& x, const A& y) {return x.data_ == y.data_;}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::nested_exception e;
@@ -55,4 +55,6 @@ int main()
         }
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/except.nested/rethrow_if_nested.pass.cpp b/libcxx/test/std/language.support/support.exception/except.nested/rethrow_if_nested.pass.cpp
index 426ea55bff9..01ef7ade7c2 100644
--- a/libcxx/test/std/language.support/support.exception/except.nested/rethrow_if_nested.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/except.nested/rethrow_if_nested.pass.cpp
@@ -56,7 +56,7 @@ class E1 : public std::nested_exception {};
 class E2 : public std::nested_exception {};
 class E : public E1, public E2 {};
 
-int main()
+int main(int, char**)
 {
     {
         try
@@ -131,4 +131,6 @@ int main()
         }
     }
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/except.nested/rethrow_nested.pass.cpp b/libcxx/test/std/language.support/support.exception/except.nested/rethrow_nested.pass.cpp
index ba81b8fe3af..204c3b567e7 100644
--- a/libcxx/test/std/language.support/support.exception/except.nested/rethrow_nested.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/except.nested/rethrow_nested.pass.cpp
@@ -31,7 +31,7 @@ void go_quietly()
     std::exit(0);
 }
 
-int main()
+int main(int, char**)
 {
     {
         try
@@ -67,4 +67,6 @@ int main()
             assert(false);
         }
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/except.nested/throw_with_nested.pass.cpp b/libcxx/test/std/language.support/support.exception/except.nested/throw_with_nested.pass.cpp
index c0bc423b01b..b63053c3304 100644
--- a/libcxx/test/std/language.support/support.exception/except.nested/throw_with_nested.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/except.nested/throw_with_nested.pass.cpp
@@ -42,7 +42,7 @@ public:
 struct Final final {};
 #endif
 
-int main()
+int main(int, char**)
 {
     {
         try
@@ -128,4 +128,6 @@ int main()
         }
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/exception.terminate/nothing_to_do.pass.cpp b/libcxx/test/std/language.support/support.exception/exception.terminate/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/language.support/support.exception/exception.terminate/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/exception.terminate/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/exception.terminate/set.terminate/get_terminate.pass.cpp b/libcxx/test/std/language.support/support.exception/exception.terminate/set.terminate/get_terminate.pass.cpp
index 2ec624ba654..851d93bc0c8 100644
--- a/libcxx/test/std/language.support/support.exception/exception.terminate/set.terminate/get_terminate.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/exception.terminate/set.terminate/get_terminate.pass.cpp
@@ -15,10 +15,12 @@
 void f1() {}
 void f2() {}
 
-int main()
+int main(int, char**)
 {
     std::set_terminate(f1);
     assert(std::get_terminate() == f1);
     std::set_terminate(f2);
     assert(std::get_terminate() == f2);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/exception.terminate/set.terminate/set_terminate.pass.cpp b/libcxx/test/std/language.support/support.exception/exception.terminate/set.terminate/set_terminate.pass.cpp
index 9eae3a45edf..e4464b9afc1 100644
--- a/libcxx/test/std/language.support/support.exception/exception.terminate/set.terminate/set_terminate.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/exception.terminate/set.terminate/set_terminate.pass.cpp
@@ -15,8 +15,10 @@
 void f1() {}
 void f2() {}
 
-int main()
+int main(int, char**)
 {
     std::set_terminate(f1);
     assert(std::set_terminate(f2) == f1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/exception.terminate/terminate.handler/terminate_handler.pass.cpp b/libcxx/test/std/language.support/support.exception/exception.terminate/terminate.handler/terminate_handler.pass.cpp
index 8f889beee8f..2519f0bc9ce 100644
--- a/libcxx/test/std/language.support/support.exception/exception.terminate/terminate.handler/terminate_handler.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/exception.terminate/terminate.handler/terminate_handler.pass.cpp
@@ -14,9 +14,11 @@
 
 void f() {}
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_same<std::terminate_handler, void(*)()>::value), "");
     std::terminate_handler p = f;
     assert(p == &f);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/exception.terminate/terminate/terminate.pass.cpp b/libcxx/test/std/language.support/support.exception/exception.terminate/terminate/terminate.pass.cpp
index 431ad8bf943..4243fb5cadf 100644
--- a/libcxx/test/std/language.support/support.exception/exception.terminate/terminate/terminate.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/exception.terminate/terminate/terminate.pass.cpp
@@ -17,9 +17,11 @@ void f1()
     std::exit(0);
 }
 
-int main()
+int main(int, char**)
 {
     std::set_terminate(f1);
     std::terminate();
     assert(false);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/exception/exception.pass.cpp b/libcxx/test/std/language.support/support.exception/exception/exception.pass.cpp
index bfb27418f53..893a7d5b363 100644
--- a/libcxx/test/std/language.support/support.exception/exception/exception.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/exception/exception.pass.cpp
@@ -12,7 +12,7 @@
 #include <type_traits>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     static_assert(std::is_polymorphic<std::exception>::value,
                  "std::is_polymorphic<std::exception>::value");
@@ -21,4 +21,6 @@ int main()
     b2 = b;
     const char* w = b2.what();
     assert(w);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/propagation/current_exception.pass.cpp b/libcxx/test/std/language.support/support.exception/propagation/current_exception.pass.cpp
index 3c265d8bb88..c95368163d4 100644
--- a/libcxx/test/std/language.support/support.exception/propagation/current_exception.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/propagation/current_exception.pass.cpp
@@ -29,7 +29,7 @@ struct A
 
 int A::constructed = 0;
 
-int main()
+int main(int, char**)
 {
     {
         std::exception_ptr p = std::current_exception();
@@ -270,4 +270,6 @@ int main()
         assert(p != nullptr);
     }
     assert(A::constructed == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/propagation/exception_ptr.pass.cpp b/libcxx/test/std/language.support/support.exception/propagation/exception_ptr.pass.cpp
index 39f2d6014dc..164e7774be9 100644
--- a/libcxx/test/std/language.support/support.exception/propagation/exception_ptr.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/propagation/exception_ptr.pass.cpp
@@ -15,7 +15,7 @@
 #include <exception>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     std::exception_ptr p;
     assert(p == nullptr);
@@ -30,4 +30,6 @@ int main()
     assert(p3 == nullptr);
     p3 = nullptr;
     assert(p3 == nullptr);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/propagation/make_exception_ptr.pass.cpp b/libcxx/test/std/language.support/support.exception/propagation/make_exception_ptr.pass.cpp
index 3db951d281f..b26212fd136 100644
--- a/libcxx/test/std/language.support/support.exception/propagation/make_exception_ptr.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/propagation/make_exception_ptr.pass.cpp
@@ -26,7 +26,7 @@ struct A
 
 int A::constructed = 0;
 
-int main()
+int main(int, char**)
 {
     {
         std::exception_ptr p = std::make_exception_ptr(A(5));
@@ -52,4 +52,6 @@ int main()
         assert(A::constructed == 0);
     }
     assert(A::constructed == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/propagation/rethrow_exception.pass.cpp b/libcxx/test/std/language.support/support.exception/propagation/rethrow_exception.pass.cpp
index ab2df72e8e8..015dbef224f 100644
--- a/libcxx/test/std/language.support/support.exception/propagation/rethrow_exception.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/propagation/rethrow_exception.pass.cpp
@@ -26,7 +26,7 @@ struct A
 
 int A::constructed = 0;
 
-int main()
+int main(int, char**)
 {
     {
         std::exception_ptr p;
@@ -60,4 +60,6 @@ int main()
         assert(A::constructed == 0);
     }
     assert(A::constructed == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/uncaught/uncaught_exception.pass.cpp b/libcxx/test/std/language.support/support.exception/uncaught/uncaught_exception.pass.cpp
index 29087eb153f..61cfc8f11c1 100644
--- a/libcxx/test/std/language.support/support.exception/uncaught/uncaught_exception.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/uncaught/uncaught_exception.pass.cpp
@@ -29,7 +29,7 @@ struct B
     }
 };
 
-int main()
+int main(int, char**)
 {
     try
     {
@@ -42,4 +42,6 @@ int main()
         assert(!std::uncaught_exception());
     }
     assert(!std::uncaught_exception());
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.exception/uncaught/uncaught_exceptions.pass.cpp b/libcxx/test/std/language.support/support.exception/uncaught/uncaught_exceptions.pass.cpp
index bab33d837e5..c25e4d2e069 100644
--- a/libcxx/test/std/language.support/support.exception/uncaught/uncaught_exceptions.pass.cpp
+++ b/libcxx/test/std/language.support/support.exception/uncaught/uncaught_exceptions.pass.cpp
@@ -41,7 +41,7 @@ struct Outer {
     int d_;
 };
 
-int main () {
+int main(int, char**) {
     assert(std::uncaught_exceptions() == 0);
     {
     Outer o(0);
@@ -58,4 +58,6 @@ int main () {
         }
     }
     assert(std::uncaught_exceptions() == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.general/nothing_to_do.pass.cpp b/libcxx/test/std/language.support/support.general/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/language.support/support.general/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/language.support/support.general/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.initlist/include_cxx03.pass.cpp b/libcxx/test/std/language.support/support.initlist/include_cxx03.pass.cpp
index 343da95f406..282636ed05b 100644
--- a/libcxx/test/std/language.support/support.initlist/include_cxx03.pass.cpp
+++ b/libcxx/test/std/language.support/support.initlist/include_cxx03.pass.cpp
@@ -12,6 +12,8 @@
 
 #include <initializer_list>
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.initlist/support.initlist.access/access.pass.cpp b/libcxx/test/std/language.support/support.initlist/support.initlist.access/access.pass.cpp
index ff532fbf267..097f21a5c69 100644
--- a/libcxx/test/std/language.support/support.initlist/support.initlist.access/access.pass.cpp
+++ b/libcxx/test/std/language.support/support.initlist/support.initlist.access/access.pass.cpp
@@ -51,11 +51,13 @@ struct B
 
 #endif  // TEST_STD_VER > 11
 
-int main()
+int main(int, char**)
 {
     A test1 = {3, 2, 1};
 #if TEST_STD_VER > 11
     constexpr B test2 = {3, 2, 1};
     (void)test2;
 #endif  // TEST_STD_VER > 11
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.initlist/support.initlist.cons/default.pass.cpp b/libcxx/test/std/language.support/support.initlist/support.initlist.cons/default.pass.cpp
index dc5c5ffd47a..8d2e0a7e713 100644
--- a/libcxx/test/std/language.support/support.initlist/support.initlist.cons/default.pass.cpp
+++ b/libcxx/test/std/language.support/support.initlist/support.initlist.cons/default.pass.cpp
@@ -19,7 +19,7 @@
 
 struct A {};
 
-int main()
+int main(int, char**)
 {
     std::initializer_list<A> il;
     assert(il.size() == 0);
@@ -28,4 +28,6 @@ int main()
     constexpr std::initializer_list<A> il2;
     static_assert(il2.size() == 0, "");
 #endif  // TEST_STD_VER > 11
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.initlist/support.initlist.range/begin_end.pass.cpp b/libcxx/test/std/language.support/support.initlist/support.initlist.range/begin_end.pass.cpp
index 61bf2708441..ec755bfeb98 100644
--- a/libcxx/test/std/language.support/support.initlist/support.initlist.range/begin_end.pass.cpp
+++ b/libcxx/test/std/language.support/support.initlist/support.initlist.range/begin_end.pass.cpp
@@ -49,11 +49,13 @@ struct B
 
 #endif  // TEST_STD_VER > 11
 
-int main()
+int main(int, char**)
 {
     A test1 = {3, 2, 1};
 #if TEST_STD_VER > 11
     constexpr B test2 = {3, 2, 1};
     (void)test2;
 #endif  // TEST_STD_VER > 11
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.initlist/types.pass.cpp b/libcxx/test/std/language.support/support.initlist/types.pass.cpp
index 9aad9b3f757..1b48980a240 100644
--- a/libcxx/test/std/language.support/support.initlist/types.pass.cpp
+++ b/libcxx/test/std/language.support/support.initlist/types.pass.cpp
@@ -25,7 +25,7 @@
 
 struct A {};
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_same<std::initializer_list<A>::value_type, A>::value), "");
     static_assert((std::is_same<std::initializer_list<A>::reference, const A&>::value), "");
@@ -33,4 +33,6 @@ int main()
     static_assert((std::is_same<std::initializer_list<A>::size_type, std::size_t>::value), "");
     static_assert((std::is_same<std::initializer_list<A>::iterator, const A*>::value), "");
     static_assert((std::is_same<std::initializer_list<A>::const_iterator, const A*>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/c.limits/cfloat.pass.cpp b/libcxx/test/std/language.support/support.limits/c.limits/cfloat.pass.cpp
index ec144a03177..12b80adf011 100644
--- a/libcxx/test/std/language.support/support.limits/c.limits/cfloat.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/c.limits/cfloat.pass.cpp
@@ -178,6 +178,8 @@
 #endif
 #endif
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/c.limits/climits.pass.cpp b/libcxx/test/std/language.support/support.limits/c.limits/climits.pass.cpp
index 317d5d5094f..d124f7ca28d 100644
--- a/libcxx/test/std/language.support/support.limits/c.limits/climits.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/c.limits/climits.pass.cpp
@@ -86,6 +86,8 @@
 #error ULLONG_MAX not defined
 #endif
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/denorm.style/check_values.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/denorm.style/check_values.pass.cpp
index 6b48dfbc379..adbd102dc20 100644
--- a/libcxx/test/std/language.support/support.limits/limits/denorm.style/check_values.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/denorm.style/check_values.pass.cpp
@@ -18,7 +18,7 @@ struct two {one _[2];};
 one test(std::float_round_style);
 two test(int);
 
-int main()
+int main(int, char**)
 {
     static_assert(std::round_indeterminate == -1,
                  "std::round_indeterminate == -1");
@@ -34,4 +34,6 @@ int main()
                  "sizeof(test(std::round_to_nearest)) == 1");
     static_assert(sizeof(test(1)) == 2,
                  "sizeof(test(1)) == 2");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/is_specialized.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/is_specialized.pass.cpp
index 4959d5f54b9..b836555afc7 100644
--- a/libcxx/test/std/language.support/support.limits/limits/is_specialized.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/is_specialized.pass.cpp
@@ -39,7 +39,7 @@ void test()
                  "std::numeric_limits<const volatile T>::is_specialized");
 }
 
-int main()
+int main(int, char**)
 {
     test<bool>();
     test<char>();
@@ -67,4 +67,6 @@ int main()
     test<long double>();
     static_assert(!std::numeric_limits<std::complex<double> >::is_specialized,
                  "!std::numeric_limits<std::complex<double> >::is_specialized");
+
+  return 0;
 }
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;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.limits/default.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.limits/default.pass.cpp
index 3c7cefd55cf..6e258c13a78 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.limits/default.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.limits/default.pass.cpp
@@ -22,7 +22,7 @@ struct A
 
 bool operator == (const A& x, const A& y) {return x.data_ == y.data_;}
 
-int main()
+int main(int, char**)
 {
     static_assert(std::numeric_limits<A>::is_specialized == false,
                  "std::numeric_limits<A>::is_specialized == false");
@@ -79,4 +79,6 @@ int main()
                  "std::numeric_limits<A>::tinyness_before == false");
     static_assert(std::numeric_limits<A>::round_style == std::round_toward_zero,
                  "std::numeric_limits<A>::round_style == std::round_toward_zero");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/numeric.special/nothing_to_do.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/numeric.special/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/language.support/support.limits/limits/numeric.special/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/numeric.special/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/limits/round.style/check_values.pass.cpp b/libcxx/test/std/language.support/support.limits/limits/round.style/check_values.pass.cpp
index c6a01bf66fb..b1a4e4450a1 100644
--- a/libcxx/test/std/language.support/support.limits/limits/round.style/check_values.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/limits/round.style/check_values.pass.cpp
@@ -18,7 +18,7 @@ struct two {one _[2];};
 one test(std::float_denorm_style);
 two test(int);
 
-int main()
+int main(int, char**)
 {
     static_assert(std::denorm_indeterminate == -1,
                  "std::denorm_indeterminate == -1");
@@ -30,4 +30,6 @@ int main()
                  "sizeof(test(std::denorm_present)) == 1");
     static_assert(sizeof(test(1)) == 2,
                  "sizeof(test(1)) == 2");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/nothing_to_do.pass.cpp b/libcxx/test/std/language.support/support.limits/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/language.support/support.limits/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/algorithm.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/algorithm.version.pass.cpp
index 57234ad4362..5458e919429 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/algorithm.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/algorithm.version.pass.cpp
@@ -188,4 +188,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/any.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/any.version.pass.cpp
index 9bbaca7aa15..f5255c0e26a 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/any.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/any.version.pass.cpp
@@ -52,4 +52,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/array.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/array.version.pass.cpp
index 85bda432290..d590f98042d 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/array.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/array.version.pass.cpp
@@ -101,4 +101,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.pass.cpp
index 3fb2c7ed147..d8f6f548cd2 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/atomic.version.pass.cpp
@@ -118,4 +118,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/bit.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/bit.version.pass.cpp
index 6c26e06a0b0..3e42d06fbe8 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/bit.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/bit.version.pass.cpp
@@ -55,4 +55,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/charconv.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/charconv.pass.cpp
index 045dcb8ac38..2afe2e26ba5 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/charconv.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/charconv.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 //  ensure that the macros that are supposed to be defined in <utility> are defined.
 
@@ -28,4 +28,6 @@ int main()
 # error "__cpp_lib_fooby has an invalid value"
 #endif
 */
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/chrono.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/chrono.version.pass.cpp
index 9e434c5c253..88da2dcca6d 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/chrono.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/chrono.version.pass.cpp
@@ -78,4 +78,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/cmath.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/cmath.version.pass.cpp
index bcc2053585a..d81218e66ab 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/cmath.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/cmath.version.pass.cpp
@@ -87,4 +87,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/compare.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/compare.version.pass.cpp
index 2864c9f4eb0..7f1836fba00 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/compare.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/compare.version.pass.cpp
@@ -55,4 +55,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/complex.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/complex.version.pass.cpp
index c6a9b16481f..bcff0bbe185 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/complex.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/complex.version.pass.cpp
@@ -55,4 +55,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/concepts.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/concepts.version.pass.cpp
index 9d9b9bca3fe..16febf8d3e2 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/concepts.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/concepts.version.pass.cpp
@@ -19,7 +19,7 @@
 #include <cassert>
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 //  ensure that the macros that are supposed to be defined in <concepts> are defined.
 
@@ -30,4 +30,6 @@ int main()
 # error "__cpp_lib_fooby has an invalid value"
 #endif
 */
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/cstddef.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/cstddef.version.pass.cpp
index 82a0932d0dc..b18ea07ea0c 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/cstddef.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/cstddef.version.pass.cpp
@@ -52,4 +52,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/deque.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/deque.version.pass.cpp
index 53a1b33450b..9d07dcdd246 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/deque.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/deque.version.pass.cpp
@@ -95,4 +95,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/exception.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/exception.version.pass.cpp
index c27bdc6b063..1ecebb48f0f 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/exception.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/exception.version.pass.cpp
@@ -52,4 +52,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/execution.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/execution.version.pass.cpp
index 476a31ef93f..b05f41bb173 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/execution.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/execution.version.pass.cpp
@@ -19,7 +19,7 @@
 #include <cassert>
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 //  ensure that the macros that are supposed to be defined in <execution> are defined.
 
@@ -30,4 +30,6 @@ int main()
 # error "__cpp_lib_fooby has an invalid value"
 #endif
 */
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/filesystem.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/filesystem.version.pass.cpp
index 6638cdee90c..d1c09fc7ee4 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/filesystem.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/filesystem.version.pass.cpp
@@ -78,4 +78,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/forward_list.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/forward_list.version.pass.cpp
index 102cd29ea56..7ecad6d3e34 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/forward_list.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/forward_list.version.pass.cpp
@@ -144,4 +144,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/functional.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/functional.version.pass.cpp
index e1146423119..a29a1d708a3 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/functional.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/functional.version.pass.cpp
@@ -241,4 +241,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/iomanip.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/iomanip.version.pass.cpp
index bd2ea2417a2..23378e0e2e3 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/iomanip.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/iomanip.version.pass.cpp
@@ -55,4 +55,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/istream.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/istream.version.pass.cpp
index 9194ff85528..3d8fb7a4cf9 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/istream.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/istream.version.pass.cpp
@@ -55,4 +55,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/iterator.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/iterator.version.pass.cpp
index b1ad28206f7..9c1719b53cf 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/iterator.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/iterator.version.pass.cpp
@@ -179,4 +179,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/limits.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/limits.version.pass.cpp
index bb2005e327c..2d2f243e704 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/limits.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/limits.version.pass.cpp
@@ -55,4 +55,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/list.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/list.version.pass.cpp
index c1159cf73a1..b736d1f9a21 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/list.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/list.version.pass.cpp
@@ -144,4 +144,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/locale.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/locale.version.pass.cpp
index c5a5b543650..eeea5390afd 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/locale.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/locale.version.pass.cpp
@@ -55,4 +55,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/map.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/map.version.pass.cpp
index c1ecad72321..a41dd1b8e98 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/map.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/map.version.pass.cpp
@@ -167,4 +167,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/memory.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/memory.version.pass.cpp
index 55e595fa9a8..6c845d71feb 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/memory.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/memory.version.pass.cpp
@@ -243,4 +243,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/memory_resource.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/memory_resource.version.pass.cpp
index cb182adc16a..d712a8bca8d 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/memory_resource.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/memory_resource.version.pass.cpp
@@ -19,7 +19,7 @@
 #include <cassert>
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 //  ensure that the macros that are supposed to be defined in <memory_resource> are defined.
 
@@ -30,4 +30,6 @@ int main()
 # error "__cpp_lib_fooby has an invalid value"
 #endif
 */
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/mutex.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/mutex.version.pass.cpp
index 4986a1f192d..9dae806b812 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/mutex.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/mutex.version.pass.cpp
@@ -52,4 +52,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/new.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/new.version.pass.cpp
index 95a717dfbd2..5f012cd55f6 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/new.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/new.version.pass.cpp
@@ -101,4 +101,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/numeric.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/numeric.version.pass.cpp
index f44cbc2c75c..eb5eb557b7b 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/numeric.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/numeric.version.pass.cpp
@@ -87,4 +87,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/optional.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/optional.version.pass.cpp
index 59e698d769d..d88fbb0fee8 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/optional.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/optional.version.pass.cpp
@@ -52,4 +52,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/ostream.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/ostream.version.pass.cpp
index 17be75c2e72..d3ba25867d0 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/ostream.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/ostream.version.pass.cpp
@@ -55,4 +55,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/regex.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/regex.version.pass.cpp
index 412e29c6c54..66becadbbfb 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/regex.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/regex.version.pass.cpp
@@ -52,4 +52,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/scoped_allocator.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/scoped_allocator.version.pass.cpp
index d111f263c13..2ea98256e1b 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/scoped_allocator.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/scoped_allocator.version.pass.cpp
@@ -52,4 +52,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/set.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/set.version.pass.cpp
index c886850ceba..80cf9c0af3c 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/set.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/set.version.pass.cpp
@@ -144,4 +144,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/shared_mutex.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/shared_mutex.version.pass.cpp
index 12c58480bdf..7c92dfc085c 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/shared_mutex.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/shared_mutex.version.pass.cpp
@@ -110,4 +110,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.pass.cpp
index 0f1c37b90e4..bdd517da0de 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/string.version.pass.cpp
@@ -170,4 +170,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.pass.cpp
index adad6b084e3..816083e0d7f 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/string_view.version.pass.cpp
@@ -104,4 +104,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/tuple.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/tuple.version.pass.cpp
index e2d9865324e..5c1e6580c57 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/tuple.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/tuple.version.pass.cpp
@@ -153,4 +153,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/type_traits.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/type_traits.version.pass.cpp
index 59994b77956..7e8b3de35f4 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/type_traits.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/type_traits.version.pass.cpp
@@ -393,4 +393,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/unordered_map.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/unordered_map.version.pass.cpp
index f6f4e6cecc2..07eb1a9bc35 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/unordered_map.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/unordered_map.version.pass.cpp
@@ -167,4 +167,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/unordered_set.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/unordered_set.version.pass.cpp
index 07a3c302adc..845318a79a5 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/unordered_set.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/unordered_set.version.pass.cpp
@@ -144,4 +144,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/utility.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/utility.version.pass.cpp
index 6b051d289d4..1fd38627a71 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/utility.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/utility.version.pass.cpp
@@ -191,4 +191,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/variant.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/variant.version.pass.cpp
index 23a15a67060..7a17307460d 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/variant.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/variant.version.pass.cpp
@@ -52,4 +52,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/vector.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/vector.version.pass.cpp
index c22921e775d..3ea2a0cf00b 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/vector.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/vector.version.pass.cpp
@@ -118,4 +118,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp
index aa409e1547a..b85d42d00ca 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.pass.cpp
@@ -2174,4 +2174,4 @@
 
 #endif // TEST_STD_VER > 17
 
-int main() {}
+int main(int, char**) { return 0; }
diff --git a/libcxx/test/std/language.support/support.limits/version.pass.cpp b/libcxx/test/std/language.support/support.limits/version.pass.cpp
index b67df2892f0..783af5c728b 100644
--- a/libcxx/test/std/language.support/support.limits/version.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/version.pass.cpp
@@ -11,6 +11,8 @@
 
 #include <version>
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.rtti/bad.cast/bad_cast.pass.cpp b/libcxx/test/std/language.support/support.rtti/bad.cast/bad_cast.pass.cpp
index 5f9dc962daf..23afd223cc4 100644
--- a/libcxx/test/std/language.support/support.rtti/bad.cast/bad_cast.pass.cpp
+++ b/libcxx/test/std/language.support/support.rtti/bad.cast/bad_cast.pass.cpp
@@ -12,7 +12,7 @@
 #include <type_traits>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::exception, std::bad_cast>::value),
                  "std::is_base_of<std::exception, std::bad_cast>::value");
@@ -23,4 +23,6 @@ int main()
     b2 = b;
     const char* w = b2.what();
     assert(w);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.rtti/bad.typeid/bad_typeid.pass.cpp b/libcxx/test/std/language.support/support.rtti/bad.typeid/bad_typeid.pass.cpp
index 90b6bc20a30..94424bb03ad 100644
--- a/libcxx/test/std/language.support/support.rtti/bad.typeid/bad_typeid.pass.cpp
+++ b/libcxx/test/std/language.support/support.rtti/bad.typeid/bad_typeid.pass.cpp
@@ -12,7 +12,7 @@
 #include <type_traits>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::exception, std::bad_typeid>::value),
                  "std::is_base_of<std::exception, std::bad_typeid>::value");
@@ -23,4 +23,6 @@ int main()
     b2 = b;
     const char* w = b2.what();
     assert(w);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.rtti/type.info/type_info.pass.cpp b/libcxx/test/std/language.support/support.rtti/type.info/type_info.pass.cpp
index fec07526a2e..980bfeeccdc 100644
--- a/libcxx/test/std/language.support/support.rtti/type.info/type_info.pass.cpp
+++ b/libcxx/test/std/language.support/support.rtti/type.info/type_info.pass.cpp
@@ -16,7 +16,7 @@
 bool test_constructor_explicit(std::type_info const&) { return false; }
 bool test_constructor_explicit(std::string const&) { return true; }
 
-int main()
+int main(int, char**)
 {
   {
     const std::type_info& t1 = typeid(int);
@@ -36,4 +36,6 @@ int main()
     // See: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=216201
     assert(test_constructor_explicit("abc"));
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.rtti/type.info/type_info_hash.pass.cpp b/libcxx/test/std/language.support/support.rtti/type.info/type_info_hash.pass.cpp
index d519622b7b1..c65f3bbf790 100644
--- a/libcxx/test/std/language.support/support.rtti/type.info/type_info_hash.pass.cpp
+++ b/libcxx/test/std/language.support/support.rtti/type.info/type_info_hash.pass.cpp
@@ -12,11 +12,13 @@
 #include <cstring>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     const std::type_info& t1 = typeid(int);
     const std::type_info& t2 = typeid(int);
     const std::type_info& t3 = typeid(short);
     assert(t1.hash_code() == t2.hash_code());
     assert(t1.hash_code() != t3.hash_code());
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.runtime/csetjmp.pass.cpp b/libcxx/test/std/language.support/support.runtime/csetjmp.pass.cpp
index dc68bf4a342..c1fa71b0e37 100644
--- a/libcxx/test/std/language.support/support.runtime/csetjmp.pass.cpp
+++ b/libcxx/test/std/language.support/support.runtime/csetjmp.pass.cpp
@@ -15,10 +15,12 @@
 #error setjmp not defined
 #endif
 
-int main()
+int main(int, char**)
 {
     std::jmp_buf jb;
     ((void)jb); // Prevent unused warning
     static_assert((std::is_same<decltype(std::longjmp(jb, 0)), void>::value),
                   "std::is_same<decltype(std::longjmp(jb, 0)), void>::value");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.runtime/csignal.pass.cpp b/libcxx/test/std/language.support/support.runtime/csignal.pass.cpp
index b827236bb7f..dcfb4f99f5f 100644
--- a/libcxx/test/std/language.support/support.runtime/csignal.pass.cpp
+++ b/libcxx/test/std/language.support/support.runtime/csignal.pass.cpp
@@ -47,11 +47,13 @@
 #error SIGTERM not defined
 #endif
 
-int main()
+int main(int, char**)
 {
     std::sig_atomic_t sig = 0;
     ((void)sig);
     typedef void (*func)(int);
     static_assert((std::is_same<decltype(std::signal(0, (func)0)), func>::value), "");
     static_assert((std::is_same<decltype(std::raise(0)), int>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.runtime/cstdarg.pass.cpp b/libcxx/test/std/language.support/support.runtime/cstdarg.pass.cpp
index b3c919af05f..8d7fd70b75a 100644
--- a/libcxx/test/std/language.support/support.runtime/cstdarg.pass.cpp
+++ b/libcxx/test/std/language.support/support.runtime/cstdarg.pass.cpp
@@ -30,8 +30,10 @@
 #error va_start not defined
 #endif
 
-int main()
+int main(int, char**)
 {
     std::va_list va;
     ((void)va);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.runtime/cstdbool.pass.cpp b/libcxx/test/std/language.support/support.runtime/cstdbool.pass.cpp
index 98a0e7e4989..461e77c9983 100644
--- a/libcxx/test/std/language.support/support.runtime/cstdbool.pass.cpp
+++ b/libcxx/test/std/language.support/support.runtime/cstdbool.pass.cpp
@@ -26,6 +26,8 @@
 #error false should not be defined
 #endif
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.runtime/cstdlib.pass.cpp b/libcxx/test/std/language.support/support.runtime/cstdlib.pass.cpp
index bc2cfcbb49d..d8b6636795d 100644
--- a/libcxx/test/std/language.support/support.runtime/cstdlib.pass.cpp
+++ b/libcxx/test/std/language.support/support.runtime/cstdlib.pass.cpp
@@ -49,7 +49,7 @@ void test_div_struct() {
     ((void) obj);
 };
 
-int main()
+int main(int, char**)
 {
     std::size_t s = 0;
     ((void)s);
@@ -108,4 +108,6 @@ int main()
     static_assert((std::is_same<decltype(std::wctomb(pc,L' ')), int>::value), "");
     static_assert((std::is_same<decltype(std::mbstowcs(pw,"",0)), std::size_t>::value), "");
     static_assert((std::is_same<decltype(std::wcstombs(pc,pwc,0)), std::size_t>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.runtime/ctime.pass.cpp b/libcxx/test/std/language.support/support.runtime/ctime.pass.cpp
index 57fb0124515..a8c2dc7ff56 100644
--- a/libcxx/test/std/language.support/support.runtime/ctime.pass.cpp
+++ b/libcxx/test/std/language.support/support.runtime/ctime.pass.cpp
@@ -26,7 +26,7 @@
 #endif
 #endif
 
-int main()
+int main(int, char**)
 {
     std::clock_t c = 0;
     std::size_t s = 0;
@@ -58,4 +58,6 @@ int main()
     ((void)c1); // Prevent unused warning
     ((void)c2); // Prevent unused warning
     static_assert((std::is_same<decltype(std::strftime(c1,s,c2,&tm)), std::size_t>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.start.term/quick_exit.pass.cpp b/libcxx/test/std/language.support/support.start.term/quick_exit.pass.cpp
index 5b7c36b08af..50d408aa0ba 100644
--- a/libcxx/test/std/language.support/support.start.term/quick_exit.pass.cpp
+++ b/libcxx/test/std/language.support/support.start.term/quick_exit.pass.cpp
@@ -13,10 +13,12 @@
 
 void f() {}
 
-int main()
+int main(int, char**)
 {
 #ifdef _LIBCPP_HAS_QUICK_EXIT
     std::at_quick_exit(f);
     std::quick_exit(0);
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.start.term/quick_exit_check1.fail.cpp b/libcxx/test/std/language.support/support.start.term/quick_exit_check1.fail.cpp
index c1703f2bee6..63c97f21025 100644
--- a/libcxx/test/std/language.support/support.start.term/quick_exit_check1.fail.cpp
+++ b/libcxx/test/std/language.support/support.start.term/quick_exit_check1.fail.cpp
@@ -15,11 +15,13 @@
 
 void f() {}
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_QUICK_EXIT
     std::at_quick_exit(f);
 #else
 #error
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.start.term/quick_exit_check2.fail.cpp b/libcxx/test/std/language.support/support.start.term/quick_exit_check2.fail.cpp
index acf10068b97..28929b1aed3 100644
--- a/libcxx/test/std/language.support/support.start.term/quick_exit_check2.fail.cpp
+++ b/libcxx/test/std/language.support/support.start.term/quick_exit_check2.fail.cpp
@@ -14,11 +14,13 @@
 
 void f() {}
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_QUICK_EXIT
     std::quick_exit(0);
 #else
 #error
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byte.pass.cpp b/libcxx/test/std/language.support/support.types/byte.pass.cpp
index a4a9e821908..842dc38d353 100644
--- a/libcxx/test/std/language.support/support.types/byte.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byte.pass.cpp
@@ -30,4 +30,6 @@ static_assert(!std::is_same<std::byte, unsigned char>::value, "" );
 // The standard doesn't outright say this, but it's pretty clear that it has to be true.
 static_assert(sizeof(std::byte) == 1, "" );
 
-int main () {}
+int main(int, char**) {
+  return 0;
+}
diff --git a/libcxx/test/std/language.support/support.types/byteops/and.assign.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/and.assign.pass.cpp
index e4875d38f33..9ecdb5f6c0d 100644
--- a/libcxx/test/std/language.support/support.types/byteops/and.assign.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/and.assign.pass.cpp
@@ -20,7 +20,7 @@ constexpr std::byte test(std::byte b1, std::byte b2) {
     }
 
 
-int main () {
+int main(int, char**) {
     std::byte b;  // not constexpr, just used in noexcept check
     constexpr std::byte b1{static_cast<std::byte>(1)};
     constexpr std::byte b8{static_cast<std::byte>(8)};
@@ -35,4 +35,6 @@ int main () {
     static_assert(std::to_integer<int>(test(b8, b1)) == 0, "");
     static_assert(std::to_integer<int>(test(b9, b1)) == 1, "");
     static_assert(std::to_integer<int>(test(b9, b8)) == 8, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/and.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/and.pass.cpp
index 312e679cd2c..d1dbc75f70c 100644
--- a/libcxx/test/std/language.support/support.types/byteops/and.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/and.pass.cpp
@@ -13,7 +13,7 @@
 
 // constexpr byte operator&(byte l, byte r) noexcept;
 
-int main () {
+int main(int, char**) {
     constexpr std::byte b1{static_cast<std::byte>(1)};
     constexpr std::byte b8{static_cast<std::byte>(8)};
     constexpr std::byte b9{static_cast<std::byte>(9)};
@@ -27,4 +27,6 @@ int main () {
     static_assert(std::to_integer<int>(b8 & b1) ==  0, "");
     static_assert(std::to_integer<int>(b9 & b1) ==  1, "");
     static_assert(std::to_integer<int>(b9 & b8) ==  8, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/enum_direct_init.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/enum_direct_init.pass.cpp
index 99660b6b180..5111667cee0 100644
--- a/libcxx/test/std/language.support/support.types/byteops/enum_direct_init.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/enum_direct_init.pass.cpp
@@ -14,7 +14,9 @@
 // XFAIL: clang-3.5, clang-3.6, clang-3.7, clang-3.8
 // XFAIL: apple-clang-6, apple-clang-7, apple-clang-8.0
 
-int main () {
+int main(int, char**) {
   constexpr std::byte b{42};
   static_assert(std::to_integer<int>(b) == 42, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/lshift.assign.fail.cpp b/libcxx/test/std/language.support/support.types/byteops/lshift.assign.fail.cpp
index 413b62b1f42..8f2134b2072 100644
--- a/libcxx/test/std/language.support/support.types/byteops/lshift.assign.fail.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/lshift.assign.fail.cpp
@@ -25,6 +25,8 @@ constexpr std::byte test(std::byte b) {
     }
 
 
-int main () {
+int main(int, char**) {
     constexpr std::byte b1 = test(std::byte{1});
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/lshift.assign.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/lshift.assign.pass.cpp
index 9fe86883f4e..3647f5c64fc 100644
--- a/libcxx/test/std/language.support/support.types/byteops/lshift.assign.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/lshift.assign.pass.cpp
@@ -22,7 +22,7 @@ constexpr std::byte test(std::byte b) {
     }
 
 
-int main () {
+int main(int, char**) {
     std::byte b;  // not constexpr, just used in noexcept check
     constexpr std::byte b2{static_cast<std::byte>(2)};
     constexpr std::byte b3{static_cast<std::byte>(3)};
@@ -32,4 +32,6 @@ int main () {
     static_assert(std::to_integer<int>(test(b2)) ==  8, "" );
     static_assert(std::to_integer<int>(test(b3)) == 12, "" );
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/lshift.fail.cpp b/libcxx/test/std/language.support/support.types/byteops/lshift.fail.cpp
index 6d889ed23e0..83ce5b81e3f 100644
--- a/libcxx/test/std/language.support/support.types/byteops/lshift.fail.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/lshift.fail.cpp
@@ -16,7 +16,9 @@
 // These functions shall not participate in overload resolution unless
 //   is_integral_v<IntegerType> is true.
 
-int main () {
+int main(int, char**) {
     constexpr std::byte b1{static_cast<std::byte>(1)};
     constexpr std::byte b2 = b1 << 2.0f;
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/lshift.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/lshift.pass.cpp
index 73cc66373c6..855eebdf4ae 100644
--- a/libcxx/test/std/language.support/support.types/byteops/lshift.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/lshift.pass.cpp
@@ -16,7 +16,7 @@
 // These functions shall not participate in overload resolution unless
 //   is_integral_v<IntegerType> is true.
 
-int main () {
+int main(int, char**) {
     constexpr std::byte b1{static_cast<std::byte>(1)};
     constexpr std::byte b3{static_cast<std::byte>(3)};
 
@@ -26,4 +26,6 @@ int main () {
     static_assert(std::to_integer<int>(b1 << 2) ==   4, "");
     static_assert(std::to_integer<int>(b3 << 4) ==  48, "");
     static_assert(std::to_integer<int>(b3 << 6) == 192, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/not.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/not.pass.cpp
index cb94e3659b6..d6252aa356e 100644
--- a/libcxx/test/std/language.support/support.types/byteops/not.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/not.pass.cpp
@@ -13,7 +13,7 @@
 
 // constexpr byte operator~(byte b) noexcept;
 
-int main () {
+int main(int, char**) {
     constexpr std::byte b1{static_cast<std::byte>(1)};
     constexpr std::byte b2{static_cast<std::byte>(2)};
     constexpr std::byte b8{static_cast<std::byte>(8)};
@@ -23,4 +23,6 @@ int main () {
     static_assert(std::to_integer<int>(~b1) == 254, "");
     static_assert(std::to_integer<int>(~b2) == 253, "");
     static_assert(std::to_integer<int>(~b8) == 247, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/or.assign.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/or.assign.pass.cpp
index cad3acef327..1216b852b82 100644
--- a/libcxx/test/std/language.support/support.types/byteops/or.assign.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/or.assign.pass.cpp
@@ -20,7 +20,7 @@ constexpr std::byte test(std::byte b1, std::byte b2) {
     }
 
 
-int main () {
+int main(int, char**) {
     std::byte b;  // not constexpr, just used in noexcept check
     constexpr std::byte b1{static_cast<std::byte>(1)};
     constexpr std::byte b2{static_cast<std::byte>(2)};
@@ -36,4 +36,6 @@ int main () {
     static_assert(std::to_integer<int>(test(b8, b1)) ==  9, "");
     static_assert(std::to_integer<int>(test(b8, b2)) == 10, "");
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/or.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/or.pass.cpp
index 4b778398d93..69b5bfaacb2 100644
--- a/libcxx/test/std/language.support/support.types/byteops/or.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/or.pass.cpp
@@ -13,7 +13,7 @@
 
 // constexpr byte operator|(byte l, byte r) noexcept;
 
-int main () {
+int main(int, char**) {
     constexpr std::byte b1{static_cast<std::byte>(1)};
     constexpr std::byte b2{static_cast<std::byte>(2)};
     constexpr std::byte b8{static_cast<std::byte>(8)};
@@ -27,4 +27,6 @@ int main () {
     static_assert(std::to_integer<int>(b2 | b1) ==  3, "");
     static_assert(std::to_integer<int>(b8 | b1) ==  9, "");
     static_assert(std::to_integer<int>(b8 | b2) == 10, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/rshift.assign.fail.cpp b/libcxx/test/std/language.support/support.types/byteops/rshift.assign.fail.cpp
index dcd6567341e..714f5cd8b13 100644
--- a/libcxx/test/std/language.support/support.types/byteops/rshift.assign.fail.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/rshift.assign.fail.cpp
@@ -25,6 +25,8 @@ constexpr std::byte test(std::byte b) {
     }
 
 
-int main () {
+int main(int, char**) {
     constexpr std::byte b1 = test(std::byte{1});
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/rshift.assign.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/rshift.assign.pass.cpp
index bbb921240bb..b1ca9d85135 100644
--- a/libcxx/test/std/language.support/support.types/byteops/rshift.assign.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/rshift.assign.pass.cpp
@@ -22,7 +22,7 @@ constexpr std::byte test(std::byte b) {
     }
 
 
-int main () {
+int main(int, char**) {
     std::byte b;  // not constexpr, just used in noexcept check
     constexpr std::byte b16{static_cast<std::byte>(16)};
     constexpr std::byte b192{static_cast<std::byte>(192)};
@@ -31,4 +31,6 @@ int main () {
 
     static_assert(std::to_integer<int>(test(b16))  ==  4, "" );
     static_assert(std::to_integer<int>(test(b192)) == 48, "" );
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/rshift.fail.cpp b/libcxx/test/std/language.support/support.types/byteops/rshift.fail.cpp
index 1dc5f83cfca..6af06f4fc68 100644
--- a/libcxx/test/std/language.support/support.types/byteops/rshift.fail.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/rshift.fail.cpp
@@ -16,7 +16,9 @@
 // These functions shall not participate in overload resolution unless
 //   is_integral_v<IntegerType> is true.
 
-int main () {
+int main(int, char**) {
     constexpr std::byte b1{static_cast<std::byte>(1)};
     constexpr std::byte b2 = b1 >> 2.0f;
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/rshift.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/rshift.pass.cpp
index 2ca3c6c20b2..64db7556cd5 100644
--- a/libcxx/test/std/language.support/support.types/byteops/rshift.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/rshift.pass.cpp
@@ -22,7 +22,7 @@ constexpr std::byte test(std::byte b) {
     }
 
 
-int main () {
+int main(int, char**) {
     constexpr std::byte b100{static_cast<std::byte>(100)};
     constexpr std::byte b115{static_cast<std::byte>(115)};
 
@@ -33,4 +33,6 @@ int main () {
     static_assert(std::to_integer<int>(b115 >> 3) ==  14, "");
     static_assert(std::to_integer<int>(b115 >> 6) ==   1, "");
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/to_integer.fail.cpp b/libcxx/test/std/language.support/support.types/byteops/to_integer.fail.cpp
index ea3836b16a4..64996358c9c 100644
--- a/libcxx/test/std/language.support/support.types/byteops/to_integer.fail.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/to_integer.fail.cpp
@@ -16,7 +16,9 @@
 // This function shall not participate in overload resolution unless
 //   is_integral_v<IntegerType> is true.
 
-int main () {
+int main(int, char**) {
     constexpr std::byte b1{static_cast<std::byte>(1)};
     auto f = std::to_integer<float>(b1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/to_integer.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/to_integer.pass.cpp
index cdae92ac4c9..657d17d9c45 100644
--- a/libcxx/test/std/language.support/support.types/byteops/to_integer.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/to_integer.pass.cpp
@@ -16,7 +16,7 @@
 // This function shall not participate in overload resolution unless
 //   is_integral_v<IntegerType> is true.
 
-int main () {
+int main(int, char**) {
     constexpr std::byte b1{static_cast<std::byte>(1)};
     constexpr std::byte b3{static_cast<std::byte>(3)};
 
@@ -27,4 +27,6 @@ int main () {
 
     static_assert(std::to_integer<int>(b1) == 1, "");
     static_assert(std::to_integer<int>(b3) == 3, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/xor.assign.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/xor.assign.pass.cpp
index 8caeec7dcc5..c82a6fd191b 100644
--- a/libcxx/test/std/language.support/support.types/byteops/xor.assign.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/xor.assign.pass.cpp
@@ -20,7 +20,7 @@ constexpr std::byte test(std::byte b1, std::byte b2) {
     }
 
 
-int main () {
+int main(int, char**) {
     std::byte b;  // not constexpr, just used in noexcept check
     constexpr std::byte b1{static_cast<std::byte>(1)};
     constexpr std::byte b8{static_cast<std::byte>(8)};
@@ -35,4 +35,6 @@ int main () {
     static_assert(std::to_integer<int>(test(b8, b1)) == 9, "");
     static_assert(std::to_integer<int>(test(b9, b1)) == 8, "");
     static_assert(std::to_integer<int>(test(b9, b8)) == 1, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/byteops/xor.pass.cpp b/libcxx/test/std/language.support/support.types/byteops/xor.pass.cpp
index 1dbf07f36c0..150f455b1db 100644
--- a/libcxx/test/std/language.support/support.types/byteops/xor.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/byteops/xor.pass.cpp
@@ -13,7 +13,7 @@
 
 // constexpr byte operator^(byte l, byte r) noexcept;
 
-int main () {
+int main(int, char**) {
     constexpr std::byte b1{static_cast<std::byte>(1)};
     constexpr std::byte b8{static_cast<std::byte>(8)};
     constexpr std::byte b9{static_cast<std::byte>(9)};
@@ -27,4 +27,6 @@ int main () {
     static_assert(std::to_integer<int>(b8 ^ b1) == 9, "");
     static_assert(std::to_integer<int>(b9 ^ b1) == 8, "");
     static_assert(std::to_integer<int>(b9 ^ b8) == 1, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/max_align_t.pass.cpp b/libcxx/test/std/language.support/support.types/max_align_t.pass.cpp
index 50c4f5ef5a6..a49f598dff7 100644
--- a/libcxx/test/std/language.support/support.types/max_align_t.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/max_align_t.pass.cpp
@@ -15,7 +15,7 @@
 #include <stdio.h>
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 
 #if TEST_STD_VER > 17
@@ -40,4 +40,6 @@ int main()
                   std::alignment_of<void*>::value,
                   "std::alignment_of<std::max_align_t>::value >= "
                   "std::alignment_of<void*>::value");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/null.pass.cpp b/libcxx/test/std/language.support/support.types/null.pass.cpp
index ce8530a00d4..66ecdbc147c 100644
--- a/libcxx/test/std/language.support/support.types/null.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/null.pass.cpp
@@ -12,6 +12,8 @@
 #error NULL not defined
 #endif
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/nullptr_t.pass.cpp b/libcxx/test/std/language.support/support.types/nullptr_t.pass.cpp
index 01a674a0a22..14ab3c65d02 100644
--- a/libcxx/test/std/language.support/support.types/nullptr_t.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/nullptr_t.pass.cpp
@@ -74,7 +74,7 @@ void test_nullptr_conversions() {
 #endif
 
 
-int main()
+int main(int, char**)
 {
     static_assert(sizeof(std::nullptr_t) == sizeof(void*),
                   "sizeof(std::nullptr_t) == sizeof(void*)");
@@ -103,4 +103,6 @@ int main()
         test_comparisons<void(*)()>();
     }
     test_nullptr_conversions();
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/nullptr_t_integral_cast.fail.cpp b/libcxx/test/std/language.support/support.types/nullptr_t_integral_cast.fail.cpp
index e6dc3772b00..5802e46f1b8 100644
--- a/libcxx/test/std/language.support/support.types/nullptr_t_integral_cast.fail.cpp
+++ b/libcxx/test/std/language.support/support.types/nullptr_t_integral_cast.fail.cpp
@@ -10,7 +10,9 @@
 
 #include <cstddef>
 
-int main()
+int main(int, char**)
 {
     std::ptrdiff_t i = static_cast<std::ptrdiff_t>(nullptr);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/nullptr_t_integral_cast.pass.cpp b/libcxx/test/std/language.support/support.types/nullptr_t_integral_cast.pass.cpp
index ab1f447cdc6..b7696df974b 100644
--- a/libcxx/test/std/language.support/support.types/nullptr_t_integral_cast.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/nullptr_t_integral_cast.pass.cpp
@@ -16,8 +16,10 @@
 #include <cstddef>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     std::ptrdiff_t i = reinterpret_cast<std::ptrdiff_t>(nullptr);
     assert(i == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/offsetof.pass.cpp b/libcxx/test/std/language.support/support.types/offsetof.pass.cpp
index 4a9dfac5e54..756f55352ed 100644
--- a/libcxx/test/std/language.support/support.types/offsetof.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/offsetof.pass.cpp
@@ -21,7 +21,9 @@ struct A
     int x;
 };
 
-int main()
+int main(int, char**)
 {
     static_assert(noexcept(offsetof(A, x)), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/ptrdiff_t.pass.cpp b/libcxx/test/std/language.support/support.types/ptrdiff_t.pass.cpp
index 9c6c36f383d..de6f7726fe2 100644
--- a/libcxx/test/std/language.support/support.types/ptrdiff_t.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/ptrdiff_t.pass.cpp
@@ -15,7 +15,7 @@
 //  2. be the same sizeof as void*.
 //  3. be a signed integral.
 
-int main()
+int main(int, char**)
 {
     static_assert(sizeof(std::ptrdiff_t) == sizeof(void*),
                   "sizeof(std::ptrdiff_t) == sizeof(void*)");
@@ -23,4 +23,6 @@ int main()
                   "std::is_signed<std::ptrdiff_t>::value");
     static_assert(std::is_integral<std::ptrdiff_t>::value,
                   "std::is_integral<std::ptrdiff_t>::value");
+
+  return 0;
 }
diff --git a/libcxx/test/std/language.support/support.types/size_t.pass.cpp b/libcxx/test/std/language.support/support.types/size_t.pass.cpp
index ba1f6467378..5c840457b37 100644
--- a/libcxx/test/std/language.support/support.types/size_t.pass.cpp
+++ b/libcxx/test/std/language.support/support.types/size_t.pass.cpp
@@ -15,7 +15,7 @@
 //  2. be the same sizeof as void*.
 //  3. be an unsigned integral.
 
-int main()
+int main(int, char**)
 {
     static_assert(sizeof(std::size_t) == sizeof(void*),
                   "sizeof(std::size_t) == sizeof(void*)");
@@ -23,4 +23,6 @@ int main()
                   "std::is_unsigned<std::size_t>::value");
     static_assert(std::is_integral<std::size_t>::value,
                   "std::is_integral<std::size_t>::value");
+
+  return 0;
 }