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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - UTIME_OMIT shouldn't be used to detect presence of utimensat()"
href="https://bugs.llvm.org/show_bug.cgi?id=33469">33469</a>
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<th>Summary</th>
<td>UTIME_OMIT shouldn't be used to detect presence of utimensat()
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<th>Product</th>
<td>libc++
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<th>Version</th>
<td>4.0
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<th>Hardware</th>
<td>Macintosh
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<th>OS</th>
<td>MacOS X
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>All Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>howarth.mailing.lists@gmail.com
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org, mclow.lists@gmail.com
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<p>
<div>
<pre>The Xcode 9 beta release breaks the assumption...
// We can use the presence of UTIME_OMIT to detect platforms that do not
// provide utimensat.
made in src/experimental/filesystem/operations.cpp. The new Xcode 9 release has
a shared SDK for both 10.12/10.13 on 10.12...
% cd /Library/Developer/CommandLineTools/SDKs
[Mac-Pro:Developer/CommandLineTools/SDKs] howarth% ls -l
total 16
drwxr-xr-x 5 root wheel 170 Jun 14 17:48 MacOSX.sdk
lrwxr-xr-x 1 root wheel 10 Jun 14 09:11 MacOSX10.12.sdk -> MacOSX.sdk
lrwxr-xr-x 1 root wheel 10 Jun 14 17:47 MacOSX10.13.sdk -> MacOSX.sdk
which results in a MacOSX.sdk/usr/include/sys/stat.h being used which
unconditionally contains...
#define UTIME_OMIT -2
This produces a undefined _utimensat symbol when '-isysroot
/Library/Developer/CommandLineTools/SDKs/MacOSX10.12.sdk
-mmacosx-version-min=10.12' is used. This is because the the
MacOSX.sdk/usr/include/sys/stat.h properly uses the __API_AVAILABLE() macro on
the utimensat()...
int utimensat(int __fd, const char *__path, const struct timespec
__times[2],
int __flag) __API_AVAILABLE(macosx(10.13), ios(11.0),
tvos(11.0), watchos(4.0));
which leaves that symbol undeclared on the 10.12 target. However
src/experimental/filesystem/operations.cpp errornously tries to use the
utimensat() call based on the definition of UTIME_OMIT.
This should be replaced with an appropriate cmake module to check for
utimensat() directly with the current compile flags rather than incorrectly
depending on the definition of UTIME_OMIT.</pre>
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