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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Clang recommends `string.h` for missing `strndup` declaration"
href="https://bugs.llvm.org/show_bug.cgi?id=50786">50786</a>
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<th>Summary</th>
<td>Clang recommends `string.h` for missing `strndup` declaration
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>12.0
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>prs.ttg+llvm@pm.me
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<th>CC</th>
<td>blitzrakete@gmail.com, dgregor@apple.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<pre>Clang recommends `string.h` for missing `strndup` declaration despite `strndup`
not being part of `string.h` under the Windows libc.
This means that compilation of something like this:
```
#include <string.h>
char* test(const char* str, size_t n) {
return strndup(str, n);
}
...
```
would result in:
```
implicitly declaring library function 'strndup' with type 'char *(const char *,
unsigned long long)' [-Wimplicit-function-declaration]
return strndup(str, n);
^
note: include the header <string.h> or explicitly provide a declaration for
'strndup'
```
which is quite misleading.
I'm not sure if there is a way to see whether a given header provides a decl
under a given compilation env, or if it would just be a case of not treating
`strndup` as a library function on windows targets.
This came to light from GH Actions CI so I can't really provide many more
details on the environment - clang seems to be installed from
'<a href="https://github.com/llvm/llvm-project/releases/download/llvmorg-12.0.0/LLVM-12.0.0-win64.exe">https://github.com/llvm/llvm-project/releases/download/llvmorg-12.0.0/LLVM-12.0.0-win64.exe</a>'
(using `egor-tensin/setup-clang@v1` for the action)</pre>
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