[libcxx] [test] Fix building create_directory in MSVC configurations

[mstorsjo]

Summary

Don't use the mode_t type - the official windows sdk doesn't have that type.
(Mingw headers does have such a typedef though.) The umask function returns
int on windows, in both header variants.

Thus just use auto to deduce the umask return type automatically.

[• Quuxplusone]

Accepted iff you add the requested comment.

libcxx/test/std/input.output/filesystems/fs.op.funcs/fs.op.create_directory/create_directory.pass.cpp

35

Please add a comment on this line: // int on Windows, mode_t on POSIX.
Otherwise someone'll just change it back in the future.

[curdeius]

LGTM with Arthur's suggestion.

[mstorsjo]

libcxx/test/std/input.output/filesystems/fs.op.funcs/fs.op.create_directory/create_directory.pass.cpp

35

Good point, will do before pushing.

libcxx/test/std/input.output/filesystems/fs.op.funcs/fs.op.create_directory/create_directory.pass.cpp

 #include "filesystem_test_helper.h"
 
 #include <sys/types.h>
 #include <sys/stat.h>
 
 using namespace fs;
 
 fs::perms read_umask() {
-    mode_t old_mask = umask(0);
+    auto old_mask = umask(0); // int on Windows, mode_t on POSIX.
     umask(old_mask); // reset the mask to the old value.
     return static_cast<fs::perms>(old_mask);
 }
 
 TEST_SUITE(filesystem_create_directory_test_suite)
 
 TEST_CASE(test_signatures)
 {