Really do make sure that last_write_time.pass.cpp still works with old clang

I *did* try to check that such kind of an issue was not introduced
by the rL315874, but clearly i failed to finish verification.

llvm-svn: 315876

1 files changed, 6 insertions, 2 deletions

diff --git a/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.last_write_time/last_write_time.pass.cpp b/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.last_write_time/last_write_time.pass.cpp
index 49da6fbd2ae..cd7a556fa4c 100644
--- a/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.last_write_time/last_write_time.pass.cpp
+++ b/libcxx/test/std/experimental/filesystem/fs.op.funcs/fs.op.last_write_time/last_write_time.pass.cpp
@@ -89,9 +89,11 @@ bool TestSupportsNegativeTimes() {
 }
 
 // In some configurations, the comparison is tautological and the test is valid.
-// We disable the warning so that we can actually test it regardless.
+// We disable the warning so that we can actually test it regardless. Also, that
+// diagnostic is pretty new, so also don't fail if old clang does not support it
 #if defined(__clang__)
 #pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunknown-warning-option"
 #pragma clang diagnostic ignored "-Wtautological-constant-compare"
 #endif
 
@@ -123,9 +125,11 @@ static const bool SupportsMaxTime = TestSupportsMaxTime();
 } // end namespace
 
 // In some configurations, the comparison is tautological and the test is valid.
-// We disable the warning so that we can actually test it regardless.
+// We disable the warning so that we can actually test it regardless. Also, that
+// diagnostic is pretty new, so also don't fail if old clang does not support it
 #if defined(__clang__)
 #pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wunknown-warning-option"
 #pragma clang diagnostic ignored "-Wtautological-constant-compare"
 #endif