[gcc(refs/users/aoliva/heads/testme)] libstdc++: testsuite: skip fs last_write_time tests if dummy

[Alexandre Oliva <aoliva@gcc.gnu.org>]

https://gcc.gnu.org/g:738640626f9ccafcdad98b657ecef8f0fa5d6fee

commit 738640626f9ccafcdad98b657ecef8f0fa5d6fee
Author: Alexandre Oliva <oliva@adacore.com>
Date:   Mon Jun 20 20:44:03 2022 -0300

    libstdc++: testsuite: skip fs last_write_time tests if dummy
    
    The last_write_time functions are defined in ways that are useful, or
    that fail immediately, depending on various macros.  When they fail
    immediately, the filesystem last_write_time.cc tests fail noisily, but
    the fail is entirely expected.
    
    Define NO_LAST_WRITE_TIME in the last_write_time.cc tests, according
    to the macros that select implementations of last_write_time, and use
    it through the new dg-require-target-fs-lwt to skip tests that are
    expected to fail.
    
    
    for  libstdc++-v3/ChangeLog
    
            * testsuite/util/testsuite_fs.h (NO_LAST_WRITE_TIME): Define
            when appropriate.
            * testsuite/lib/libstdc++.exp
            (check_v3_target_fs_last_write_time): New.
            * testsuite/lib/dg-options.exp (dg-require-target-fs-lwt):
            New.
            * testsuite/27_io/filesystem/operations/last_write_time.cc:
            Skip the test if the features are unavailable.
            * testsuite/experimental/filesystem/operations/last_write_time.cc:
            Likewise.

Diff:
---
 .../testsuite/27_io/filesystem/operations/last_write_time.cc     | 1 +
 .../experimental/filesystem/operations/last_write_time.cc        | 1 +
 libstdc++-v3/testsuite/lib/dg-options.exp                        | 9 +++++++++
 libstdc++-v3/testsuite/lib/libstdc++.exp                         | 8 ++++++++
 libstdc++-v3/testsuite/util/testsuite_fs.h                       | 5 +++++
 5 files changed, 24 insertions(+)

diff --git a/libstdc++-v3/testsuite/27_io/filesystem/operations/last_write_time.cc b/libstdc++-v3/testsuite/27_io/filesystem/operations/last_write_time.cc
index 7d6468a5124..f6460fb83d7 100644
--- a/libstdc++-v3/testsuite/27_io/filesystem/operations/last_write_time.cc
+++ b/libstdc++-v3/testsuite/27_io/filesystem/operations/last_write_time.cc
@@ -17,6 +17,7 @@
 
 // { dg-do run { target c++17 } }
 // { dg-require-filesystem-ts "" }
+// { dg-require-target-fs-lwt "" }
 
 // 15.25 Permissions [fs.op.last_write_time]
 
diff --git a/libstdc++-v3/testsuite/experimental/filesystem/operations/last_write_time.cc b/libstdc++-v3/testsuite/experimental/filesystem/operations/last_write_time.cc
index 38fafc392ca..a0bf01ea935 100644
--- a/libstdc++-v3/testsuite/experimental/filesystem/operations/last_write_time.cc
+++ b/libstdc++-v3/testsuite/experimental/filesystem/operations/last_write_time.cc
@@ -18,6 +18,7 @@
 // { dg-options "-DUSE_FILESYSTEM_TS -lstdc++fs" }
 // { dg-do run { target c++11 } }
 // { dg-require-filesystem-ts "" }
+// { dg-require-target-fs-lwt "" }
 
 // 15.25 Permissions [fs.op.last_write_time]
 
diff --git a/libstdc++-v3/testsuite/lib/dg-options.exp b/libstdc++-v3/testsuite/lib/dg-options.exp
index 81bb8f448bd..b61c4c0cb8f 100644
--- a/libstdc++-v3/testsuite/lib/dg-options.exp
+++ b/libstdc++-v3/testsuite/lib/dg-options.exp
@@ -259,6 +259,15 @@ proc dg-require-target-fs-space { args } {
     return
 }
 
+proc dg-require-target-fs-lwt { args } {
+    if { ![ check_v3_target_fs_last_write_time ] } {
+	upvar dg-do-what dg-do-what
+	set dg-do-what [list [lindex ${dg-do-what} 0] "N" "P"]
+	return
+    }
+    return
+}
+
 proc add_options_for_no_pch { flags } {
     # This forces any generated and possibly included PCH to be invalid.
     return "-D__GLIBCXX__=99999999"
diff --git a/libstdc++-v3/testsuite/lib/libstdc++.exp b/libstdc++-v3/testsuite/lib/libstdc++.exp
index 4305ec60994..0338b50897f 100644
--- a/libstdc++-v3/testsuite/lib/libstdc++.exp
+++ b/libstdc++-v3/testsuite/lib/libstdc++.exp
@@ -1286,6 +1286,14 @@ proc check_v3_target_fs_space { } {
     return [v3_check_preprocessor_condition fs_space $cond $inc]
 }
 
+# Return 1 if the libstdc++ filesystem implementation of
+# last_write_time is not an always-failing dummy.
+proc check_v3_target_fs_last_write_time { } {
+    set inc "#include <testsuite_fs.h>"
+    set cond "!defined NO_LAST_WRITE_TIME"
+    return [v3_check_preprocessor_condition fs_last_write_time $cond $inc]
+}
+
 # Return 1 if the "cxx11" ABI is in use using the current flags, 0 otherwise.
 # Any flags provided by RUNTESTFLAGS or a target board will be used here.
 # Flags added in the test by dg-options or dg-add-options will not be used.
diff --git a/libstdc++-v3/testsuite/util/testsuite_fs.h b/libstdc++-v3/testsuite/util/testsuite_fs.h
index e9fb4fff8f2..29d0b029b75 100644
--- a/libstdc++-v3/testsuite/util/testsuite_fs.h
+++ b/libstdc++-v3/testsuite/util/testsuite_fs.h
@@ -51,6 +51,11 @@ namespace test_fs = std::experimental::filesystem;
 #define NO_SPACE
 #endif
 
+#if !(_GLIBCXX_HAVE_SYS_STAT_H \
+      && (_GLIBCXX_USE_UTIMENSAT || _GLIBCXX_USE_UTIME))
+#define NO_LAST_WRITE_TIME 1
+#endif
+
 namespace __gnu_test
 {
 #define PATH_CHK(p1, p2, fn) \