[PATCH] D34249: [libc++] Don't use UTIME_OMIT to detect utimensat on Apple

[Duncan P. N. Exon Smith via Phabricator via cfe-commits]

dexonsmith added a comment.

This is the right idea, although it only covers macOS.

Any ideas for how to test this?



================
Comment at: src/experimental/filesystem/operations.cpp:23-28
+// We can use the presence of UTIME_OMIT to detect platforms that do not
+// provide utimensat, with some exceptions on OS X.
+#if !defined(UTIME_OMIT) || \
+   (defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && __MAC_OS_X_VERSION_MIN_REQUIRED < 1030)
+#define _LIBCPP_HAS_NO_UTIMENSAT
+#endif
----------------
Sadly this isn't quite sufficient.  As per Jack's suggested SDK patch in the PR, we need to enumerate the platforms :/.  I think this should be the right logic for the four Darwin platforms:

    (defined(__IPHONE_OS_VERSION_MIN_REQUIRED) && __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_11_0) || \
    (defined(__WATCH_OS_VERSION_MIN_REQUIRED) &&  __WATCH_OS_VERSION_MIN_REQUIRED < __WATCHOS_4_0)  || \
    (defined(__TV_OS_VERSION_MIN_REQUIRED) && __TV_OS_VERSION_MIN_REQUIRED < __TVOS_11_0)           || \
    (defined(__MAC_OS_X_VERSION_MIN_REQUIRED) && __MAC_OS_X_VERSION_MIN_REQUIRED < __MAC_10_13)



https://reviews.llvm.org/D34249