[libc++][lit][AIX] Enable test case last_write_time.pass.cpp for AIX

[xingxue]

Summary

This patch enables libc++ LIT test case last_write_time.pass.cpp for AIX. Because system call utimensat() of AIX which is used in the libc++ implementation of last_write_time() does not accept the times parameter with a negative tv_sec or tv_nsec field, testing of setting file time to before epoch time is excluded for AIX.

This is the AIX utimensat() man page, noting utimensat() returns -1 with errno set to EINVAL - The Times parameter has a negative tv_sec field.

[ldionne]

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

501–502

Instead, can we move the comment above to here, always define before_epoch_time & friends, and only have one #ifdef block? That will reduce the scope of the workaround.

[xingxue]

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

501–502

Defining before_epoch_time and friends without using them will fail the test because of -Werror,-Wunused-variable.

[ldionne]

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

501–502

You can use (void) to silence it!

[xingxue]

Addressed comments:

• always define before_epoch_time & friends to reduce the scope of the workaround.

[xingxue]

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

501–502

Ah, I see, thanks!

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

 //===----------------------------------------------------------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03
 
-// XFAIL: LIBCXX-AIX-FIXME
-
 // The string reported on errors changed, which makes those tests fail when run
 // against already-released libc++'s.
 // XFAIL: use_system_cxx_lib && target={{.+}}-apple-macosx{{10.15|11.0}}
 
 // <filesystem>
 
 // file_time_type last_write_time(const path& p);
 // file_time_type last_write_time(const path& p, std::error_code& ec) noexcept;
static int stat_file(const char *path, StatT *buf, int flags) {
   return ret;
 }
 static int stat(const char *path, StatT *buf) {
   return stat_file(path, buf, 0);
 }
 static int lstat(const char *path, StatT *buf) {
   return stat_file(path, buf, FILE_FLAG_OPEN_REPARSE_POINT);
 }
+#elif defined(_AIX)
+using TimeSpec = st_timespec_t;
+using StatT = struct stat;
 #else
 using TimeSpec = timespec;
 using StatT = struct stat;
 #endif
 
 #if defined(__APPLE__)
 TimeSpec extract_mtime(StatT const& st) { return st.st_mtimespec; }
 TimeSpec extract_atime(StatT const& st) { return st.st_atimespec; }
TEST_CASE(set_last_write_time_dynamic_env_test)
     const path dir = env.create_dir("dir");
     const auto now = Clock::now();
     const file_time_type epoch_time = now - now.time_since_epoch();
 
     const file_time_type future_time = now + Hours(3) + Sec(42) + SubSec(17);
     const file_time_type past_time = now - Minutes(3) - Sec(42) - SubSec(17);
     const file_time_type before_epoch_time =
         epoch_time - Minutes(3) - Sec(42) - SubSec(17);
+    (void)before_epoch_time;
     // FreeBSD has a bug in their utimes implementation where the time is not update
     // when the number of seconds is '-1'.
 #if defined(__FreeBSD__) || defined(__NetBSD__)
     const file_time_type just_before_epoch_time =
         epoch_time - Sec(2) - SubSec(17);
 #else
     const file_time_type just_before_epoch_time = epoch_time - SubSec(17);
+    (void)just_before_epoch_time;
 #endif
 
     struct TestCase {
       const char * case_name;
       path p;
       file_time_type new_time;
     } cases[] = {
         {"file, epoch_time", file, epoch_time},
         {"dir, epoch_time", dir, epoch_time},
         {"file, future_time", file, future_time},
         {"dir, future_time", dir, future_time},
         {"file, past_time", file, past_time},
-        {"dir, past_time", dir, past_time},
+        {"dir, past_time", dir, past_time}
+        // Exclude file time types of before epoch time from testing on AIX
+        // because AIX system call utimensat() does not accept the times
+        // parameter having a negative tv_sec or tv_nsec field.
+#if !defined(_AIX)
+        ,
         {"file, before_epoch_time", file, before_epoch_time},
         {"dir, before_epoch_time", dir, before_epoch_time},
         {"file, just_before_epoch_time", file, just_before_epoch_time},
         {"dir, just_before_epoch_time", dir, just_before_epoch_time}
+#endif
     };
+
     for (const auto& TC : cases) {
         const auto old_times = GetTimes(TC.p);
         file_time_type old_time;
         TEST_REQUIRE(ConvertFromTimeSpec(old_time, old_times.write));
 
         std::error_code ec = GetTestEC();
         last_write_time(TC.p, TC.new_time, ec);
         TEST_CHECK(!ec);