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

14 files changed, 42 insertions, 14 deletions

diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/member_swap.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/member_swap.pass.cpp
index b5dce8fb914..6977d3189cf 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/member_swap.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/member_swap.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf1("testing");
@@ -60,4 +60,6 @@ int main()
         assert(buf.str() == L"testing");
         assert(buf1.str() == L"");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/move.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/move.pass.cpp
index 2a469ebb79a..653edc0d19c 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/move.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/move.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf1("testing");
@@ -54,4 +54,6 @@ int main()
         buf = move(buf1);
         assert(buf.str() == L"testing");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/nonmember_swap.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/nonmember_swap.pass.cpp
index 5a57f902af3..38562fc3220 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/nonmember_swap.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/nonmember_swap.pass.cpp
@@ -18,7 +18,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf1("testing");
@@ -62,4 +62,6 @@ int main()
         assert(buf.str() == L"testing");
         assert(buf1.str() == L"");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/default.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/default.pass.cpp
index 2121a7a842e..836509f2fdd 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/default.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/default.pass.cpp
@@ -31,7 +31,7 @@ struct testbuf
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf;
@@ -49,4 +49,6 @@ int main()
         testbuf<wchar_t> buf;
         buf.check();
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/move.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/move.pass.cpp
index 70eff738492..a3cccd39c87 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/move.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/move.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf1("testing");
@@ -48,4 +48,6 @@ int main()
         std::wstringbuf buf(move(buf1));
         assert(buf.str() == L"testing");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/string.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/string.pass.cpp
index 607d314255b..de211c80ea1 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/string.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/string.pass.cpp
@@ -17,7 +17,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf("testing");
@@ -43,4 +43,6 @@ int main()
         std::wstringbuf buf(L"testing", std::ios_base::out);
         assert(buf.str() == L"testing");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.members/str.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.members/str.pass.cpp
index baf406b696c..78b572454a5 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.members/str.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.members/str.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf("testing");
@@ -30,4 +30,6 @@ int main()
         buf.str(L"another test");
         assert(buf.str() == L"another test");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/overflow.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/overflow.pass.cpp
index 0f833070525..c9fdd0abcc9 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/overflow.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/overflow.pass.cpp
@@ -34,7 +34,7 @@ struct testbuf
     void pbump(int n) {base::pbump(n);}
 };
 
-int main()
+int main(int, char**)
 {
     {  // sanity check
     testbuf<char> tb("");
@@ -97,4 +97,6 @@ int main()
         assert(sb.sputc('2') == '2');
         assert(sb.str() == "abc12");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/pbackfail.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/pbackfail.pass.cpp
index dfbe2084b9d..458e393c8ec 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/pbackfail.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/pbackfail.pass.cpp
@@ -32,7 +32,7 @@ struct testbuf
     void pbump(int n) {base::pbump(n);}
 };
 
-int main()
+int main(int, char**)
 {
     {  // sanity check
     testbuf<char> tb("");
@@ -92,4 +92,6 @@ int main()
         assert(sb.pbackfail(std::char_traits<wchar_t>::eof()) == std::char_traits<wchar_t>::eof());
         assert(sb.str() == L"133");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp
index dbe117eaa17..1bee5c216a5 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp
@@ -17,7 +17,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf sb(std::ios_base::in);
@@ -163,4 +163,6 @@ int main()
         assert(sb.sputc(L'c') == L'c');
         assert(sb.str() == L"0123456c89");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekpos.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekpos.pass.cpp
index 7d687e070c1..fde91e74ba0 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekpos.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekpos.pass.cpp
@@ -17,7 +17,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf sb("0123456789", std::ios_base::in);
@@ -73,4 +73,6 @@ int main()
         assert(sb.sputc(L'3') == L'3');
         assert(sb.str() == L"0123456789");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/setbuf.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/setbuf.pass.cpp
index 99bc75e6c8a..f833debe39d 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/setbuf.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/setbuf.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf sb("0123456789");
@@ -28,4 +28,6 @@ int main()
         assert(sb.pubsetbuf(0, 0) == &sb);
         assert(sb.str() == L"0123456789");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/underflow.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/underflow.pass.cpp
index c3244985749..23b77d229ca 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/underflow.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/underflow.pass.cpp
@@ -28,7 +28,7 @@ struct testbuf
     void pbump(int n) {base::pbump(n);}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("123");
@@ -66,4 +66,6 @@ int main()
         assert(sb.underflow() == L'4');
         assert(sb.underflow() == L'4');
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/types.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/types.pass.cpp
index 29d651fc5e5..c27db853599 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/types.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/types.pass.cpp
@@ -23,7 +23,7 @@
 #include <sstream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::basic_streambuf<char>, std::basic_stringbuf<char> >::value), "");
     static_assert((std::is_same<std::basic_stringbuf<char>::char_type, char>::value), "");
@@ -32,4 +32,6 @@ int main()
     static_assert((std::is_same<std::basic_stringbuf<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_stringbuf<char>::off_type, std::char_traits<char>::off_type>::value), "");
     static_assert((std::is_same<std::basic_stringbuf<char>::allocator_type, std::allocator<char> >::value), "");
+
+  return 0;
 }