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/numerics/numarray/template.slice.array/slice.arr.comp.assign/addition.pass.cpp b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/addition.pass.cpp
index 5934c2015c4..0433877e749 100644
--- a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/addition.pass.cpp
+++ b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/addition.pass.cpp
@@ -15,7 +15,7 @@
 #include <valarray>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     int a1[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
     int a2[] = {-1, -2, -3, -4, -5};
@@ -39,4 +39,6 @@ int main()
     assert(v1[13] ==  8);
     assert(v1[14] == 14);
     assert(v1[15] == 15);
+
+  return 0;
 }
diff --git a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/and.pass.cpp b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/and.pass.cpp
index 3af46538bad..90bbe4ef333 100644
--- a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/and.pass.cpp
+++ b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/and.pass.cpp
@@ -15,7 +15,7 @@
 #include <valarray>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     int a1[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
     int a2[] = {1, 2, 3, 4, 5};
@@ -39,4 +39,6 @@ int main()
     assert(v1[13] ==  5);
     assert(v1[14] == 14);
     assert(v1[15] == 15);
+
+  return 0;
 }
diff --git a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/divide.pass.cpp b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/divide.pass.cpp
index 508ebbbd8ca..ae1383b84bd 100644
--- a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/divide.pass.cpp
+++ b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/divide.pass.cpp
@@ -15,7 +15,7 @@
 #include <valarray>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     int a1[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
     int a2[] = {-1, -2, -3, -4, -5};
@@ -39,4 +39,6 @@ int main()
     assert(v1[13] == -2);
     assert(v1[14] == 14);
     assert(v1[15] == 15);
+
+  return 0;
 }
diff --git a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/modulo.pass.cpp b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/modulo.pass.cpp
index 7b3919e49f0..89c1acfb381 100644
--- a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/modulo.pass.cpp
+++ b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/modulo.pass.cpp
@@ -15,7 +15,7 @@
 #include <valarray>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     int a1[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
     int a2[] = {-1, -2, -3, -4, -5};
@@ -39,4 +39,6 @@ int main()
     assert(v1[13] ==  3);
     assert(v1[14] == 14);
     assert(v1[15] == 15);
+
+  return 0;
 }
diff --git a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/multiply.pass.cpp b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/multiply.pass.cpp
index ffcd8542419..b7c6b13530a 100644
--- a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/multiply.pass.cpp
+++ b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/multiply.pass.cpp
@@ -15,7 +15,7 @@
 #include <valarray>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     int a1[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
     int a2[] = {-1, -2, -3, -4, -5};
@@ -39,4 +39,6 @@ int main()
     assert(v1[13] == -65);
     assert(v1[14] == 14);
     assert(v1[15] == 15);
+
+  return 0;
 }
diff --git a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/or.pass.cpp b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/or.pass.cpp
index b4054423447..0f37579e86d 100644
--- a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/or.pass.cpp
+++ b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/or.pass.cpp
@@ -15,7 +15,7 @@
 #include <valarray>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     int a1[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
     int a2[] = {1, 2, 3, 4, 5};
@@ -39,4 +39,6 @@ int main()
     assert(v1[13] == 13);
     assert(v1[14] == 14);
     assert(v1[15] == 15);
+
+  return 0;
 }
diff --git a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/shift_left.pass.cpp b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/shift_left.pass.cpp
index fcf51bb1857..547a8cd279a 100644
--- a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/shift_left.pass.cpp
+++ b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/shift_left.pass.cpp
@@ -15,7 +15,7 @@
 #include <valarray>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     int a1[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
     int a2[] = {1, 2, 3, 4, 5};
@@ -39,4 +39,6 @@ int main()
     assert(v1[13] == 416);
     assert(v1[14] == 14);
     assert(v1[15] == 15);
+
+  return 0;
 }
diff --git a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/shift_right.pass.cpp b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/shift_right.pass.cpp
index 4c79b559b02..99c4ef94311 100644
--- a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/shift_right.pass.cpp
+++ b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/shift_right.pass.cpp
@@ -15,7 +15,7 @@
 #include <valarray>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     int a1[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
     int a2[] = {1, 2, 3, 4, 5};
@@ -39,4 +39,6 @@ int main()
     assert(v1[13] ==  0);
     assert(v1[14] == 14);
     assert(v1[15] == 15);
+
+  return 0;
 }
diff --git a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/subtraction.pass.cpp b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/subtraction.pass.cpp
index aae003cf318..db513bc9629 100644
--- a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/subtraction.pass.cpp
+++ b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/subtraction.pass.cpp
@@ -15,7 +15,7 @@
 #include <valarray>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     int a1[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
     int a2[] = {-1, -2, -3, -4, -5};
@@ -39,4 +39,6 @@ int main()
     assert(v1[13] == 18);
     assert(v1[14] == 14);
     assert(v1[15] == 15);
+
+  return 0;
 }
diff --git a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/xor.pass.cpp b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/xor.pass.cpp
index afebc882049..4ecba47238e 100644
--- a/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/xor.pass.cpp
+++ b/libcxx/test/std/numerics/numarray/template.slice.array/slice.arr.comp.assign/xor.pass.cpp
@@ -15,7 +15,7 @@
 #include <valarray>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     int a1[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15};
     int a2[] = {1, 2, 3, 4, 5};
@@ -39,4 +39,6 @@ int main()
     assert(v1[13] ==  8);
     assert(v1[14] == 14);
     assert(v1[15] == 15);
+
+  return 0;
 }