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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - __builtin_wmemchr does not work with clang-cl"
href="https://bugs.llvm.org/show_bug.cgi?id=41226">41226</a>
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<th>Summary</th>
<td>__builtin_wmemchr does not work with clang-cl
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>8.0
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>other
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>release blocker
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>C++'17
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
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<th>Reporter</th>
<td>powerchord@web.de
</td>
</tr>
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<th>CC</th>
<td>blitzrakete@gmail.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>int main()
{
static_assert(__has_feature(cxx_constexpr_string_builtins)); // is true
static_assert(__has_builtin(__builtin_wmemchr)); // is true
static_assert(!__builtin_wmemchr(nullptr, 0, 0)); // is true
__builtin_wmemchr(nullptr, 0, 0); // no error reported
}
This program does not compile.
link.exe reports this error:
LNK2019 unresolved external symbol _wmemchr referenced in function _main
lld-link.exe reports this error:
undefined symbol: _wmemchr
This issue is related to <a class="bz_bug_link
bz_status_NEW "
title="NEW - clang-cl emits bogus error LNK2019: unresolved external symbol _wmemchr"
href="show_bug.cgi?id=37911">Bug 37911</a>
(<a class="bz_bug_link
bz_status_NEW "
title="NEW - clang-cl emits bogus error LNK2019: unresolved external symbol _wmemchr"
href="show_bug.cgi?id=37911#c1">https://bugs.llvm.org/show_bug.cgi?id=37911#c1</a>) reported by Stephan Lavavej
from Microsoft.
It seems that if __builtin_wmemchr is not forced to be evaluated at compile
time it is not "called" and clang emits the symbol _wmemchr instead. But
Microsoft's libraries do not have that symbol.
I think this is a bug. clang should be able to "call" its builtin function at
both compile time and run-time.
Maybe this is a leftover from previous clang versions, that is, before wmemchr
was made constexpr and builtin?
I tested this in VS 2017 and 2019 RC with the LLVM Compiler Toolchain
extension.</pre>
</div>
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