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

10 files changed, 30 insertions, 10 deletions

diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/T_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/T_size_size.pass.cpp
index b0541712257..044b3724041 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/T_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/T_size_size.pass.cpp
@@ -70,7 +70,7 @@ test_npos(S s, SV sv, typename S::size_type pos, S expected)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -191,4 +191,6 @@ int main()
     s.assign(sv, 0, std::string::npos);
     assert(s == "ABCDEFGHIJKLMNOPQRSTUVWXYZ");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/initializer_list.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/initializer_list.pass.cpp
index 72097dae630..692b84b557d 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/initializer_list.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/initializer_list.pass.cpp
@@ -18,7 +18,7 @@
 #include "test_macros.h"
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::string s("123");
@@ -31,4 +31,6 @@ int main()
         s.assign({'a', 'b', 'c'});
         assert(s == "abc");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/iterator.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/iterator.pass.cpp
index 4bf805c99d6..c03b5efdfd5 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/iterator.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/iterator.pass.cpp
@@ -43,7 +43,7 @@ test_exceptions(S s, It first, It last)
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -204,4 +204,6 @@ int main()
     s.assign(p, p + 4);
     assert(s == "ABCD");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer.pass.cpp
index 62a173a186d..325c354c56a 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer.pass.cpp
@@ -26,7 +26,7 @@ test(S s, const typename S::value_type* str, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -74,4 +74,6 @@ int main()
     s_long.assign(s_long.c_str() + 30);
     assert(s_long == "nsectetur/");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer_size.pass.cpp
index 442d8c00024..5d3fe262184 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer_size.pass.cpp
@@ -27,7 +27,7 @@ test(S s, const typename S::value_type* str, typename S::size_type n, S expected
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -85,4 +85,6 @@ int main()
     s_long.assign(s_long.data() + 2, 8 );
     assert(s_long == "rem ipsu");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/rv_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/rv_string.pass.cpp
index 3d401c8a917..ac26f369ddb 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/rv_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/rv_string.pass.cpp
@@ -27,7 +27,7 @@ test(S s, S str, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -77,4 +77,6 @@ int main()
          S("12345678901234567890"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/size_char.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/size_char.pass.cpp
index 8c69b138f9f..4e5ecad2e9d 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/size_char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/size_char.pass.cpp
@@ -26,7 +26,7 @@ test(S s, typename S::size_type n, typename S::value_type c, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -60,4 +60,6 @@ int main()
     test(S("12345678901234567890"), 10, 'a', S(10, 'a'));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string.pass.cpp
index 274703a565d..fae45c80de0 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string.pass.cpp
@@ -37,7 +37,7 @@ testAlloc(S s, S str, const typename S::allocator_type& a)
     assert(s.get_allocator() == a);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -113,4 +113,6 @@ int main()
     static_assert(noexcept(S().assign(S())), "");  // LWG#2063
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_size_size.pass.cpp
index 76dd273455b..8e11b150e91 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_size_size.pass.cpp
@@ -71,7 +71,7 @@ test_npos(S s, S str, typename S::size_type pos, S expected)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -133,4 +133,6 @@ int main()
     test_npos(S(), S("12345"), 5, S(""));
     test_npos(S(), S("12345"), 6, S("not happening"));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_view.pass.cpp
index d445ad9b793..2d1158e41de 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_view.pass.cpp
@@ -38,7 +38,7 @@ testAlloc(S s, SV sv, const typename S::allocator_type& a)
     assert(s.get_allocator() == a);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -101,4 +101,6 @@ int main()
     testAlloc(S(), SV("12345678901234567890"), min_allocator<char>());
     }
 #endif
+
+  return 0;
 }