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

18 files changed, 54 insertions, 18 deletions

diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.pointer.pass.cpp
index bb6c3431652..e771bd328a9 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.pointer.pass.cpp
@@ -27,7 +27,7 @@ test(S lhs, const typename S::value_type* rhs, bool x)
     assert((rhs == lhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -65,4 +65,6 @@ int main()
     static_assert (!("abcde0" == sv2), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string.pass.cpp
index bb142b0b3c3..d27d4c44588 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string.pass.cpp
@@ -25,7 +25,7 @@ test(const std::string &lhs, S rhs, bool x)
     assert((rhs == lhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -46,5 +46,7 @@ int main()
     test("abcdefghijklmnopqrst", S("abcdefghij"), false);
     test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), true);
     }
+
+  return 0;
 }
 
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string_view.pass.cpp
index d7b113c120b..259711e3c52 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string_view.pass.cpp
@@ -26,7 +26,7 @@ test(S lhs, S rhs, bool x)
     assert((rhs == lhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -58,4 +58,6 @@ int main()
     static_assert (!(sv1 == sv3), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.pointer.pass.cpp
index 4f32425dc49..5fa57eb394c 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.pointer.pass.cpp
@@ -27,7 +27,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x, bool y)
     assert((rhs >= lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -68,4 +68,6 @@ int main()
     static_assert (  "abcde0" >= sv2, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string.pass.cpp
index 9cbe389cd48..dddaa390ed3 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string.pass.cpp
@@ -25,7 +25,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x, bool y)
     assert((rhs >= lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -46,4 +46,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghij", true, false);
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", true, true);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string_view.pass.cpp
index 81fee1f3953..d35bea575c8 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string_view.pass.cpp
@@ -26,7 +26,7 @@ test(const S& lhs, const S& rhs, bool x, bool y)
     assert((rhs >= lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -61,4 +61,6 @@ int main()
     static_assert (  sv2 >= sv1,  "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.pointer.pass.cpp
index c295645a9b7..80dcc7b497b 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.pointer.pass.cpp
@@ -27,7 +27,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x, bool y)
     assert((rhs > lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -68,4 +68,6 @@ int main()
     static_assert (  "abcde0" > sv2, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string.pass.cpp
index b07b6a7aca2..84c9478bfc5 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string.pass.cpp
@@ -25,7 +25,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x, bool y)
     assert((rhs > lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -46,4 +46,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghij", true, false);
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", false, false);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string_view.pass.cpp
index 984f2c6a32e..ec31d5c2c1d 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string_view.pass.cpp
@@ -26,7 +26,7 @@ test(const S& lhs, const S& rhs, bool x, bool y)
     assert((rhs > lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -61,4 +61,6 @@ int main()
     static_assert (  sv2 > sv1, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.pointer.pass.cpp
index 81d0d167a00..4f582239a83 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.pointer.pass.cpp
@@ -27,7 +27,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x, bool y)
     assert((rhs <= lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -68,4 +68,6 @@ int main()
     static_assert (!("abcde0" <= sv2), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string.pass.cpp
index 3cdb0215e48..80e80757bf9 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string.pass.cpp
@@ -25,7 +25,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x, bool y)
     assert((rhs <= lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -46,4 +46,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghij", false, true);
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", true, true);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string_view.pass.cpp
index 3ec0222f66f..b1c18612425 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string_view.pass.cpp
@@ -26,7 +26,7 @@ test(const S& lhs, const S& rhs, bool x, bool y)
     assert((rhs <= lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -61,4 +61,6 @@ int main()
     static_assert (!(sv2 <= sv1), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.pointer.pass.cpp
index f8093c86a73..14bba2abfe6 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.pointer.pass.cpp
@@ -27,7 +27,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x, bool y)
     assert((rhs < lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -68,4 +68,6 @@ int main()
     static_assert (!("abcde0" < sv2), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string.pass.cpp
index e7341f17d1f..f611bac7a84 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string.pass.cpp
@@ -25,7 +25,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x, bool y)
     assert((rhs < lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -46,4 +46,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghij", false, true);
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", false, false);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string_view.pass.cpp
index a7e51f9af8c..f44e373619a 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string_view.pass.cpp
@@ -26,7 +26,7 @@ test(const S& lhs, const S& rhs, bool x, bool y)
     assert((rhs < lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -61,4 +61,6 @@ int main()
     static_assert (!(sv2 < sv1), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.pointer.pass.cpp
index 1531626a884..6b8add83146 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.pointer.pass.cpp
@@ -27,7 +27,7 @@ test(S lhs, const typename S::value_type* rhs, bool x)
     assert((rhs != lhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -66,4 +66,6 @@ int main()
     static_assert (  "abcde0" != sv2, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string.pass.cpp
index 8e5539a8079..613eaf7b32f 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string.pass.cpp
@@ -25,7 +25,7 @@ test(const std::string &lhs, S rhs, bool x)
     assert((rhs != lhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -46,4 +46,6 @@ int main()
     test("abcdefghijklmnopqrst", S("abcdefghij"), true);
     test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), false);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string_view.pass.cpp
index 0e01e94db43..90d153335ff 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string_view.pass.cpp
@@ -26,7 +26,7 @@ test(S lhs, S rhs, bool x)
     assert((rhs != lhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -58,4 +58,6 @@ int main()
     static_assert (   sv1 != sv3,  "" );
     }
 #endif
+
+  return 0;
 }