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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [modules] #include "stddef.h" breaks module map search paths; causes redefinitions."
href="https://llvm.org/bugs/show_bug.cgi?id=31905">31905</a>
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<th>Summary</th>
<td>[modules] #include "stddef.h" breaks module map search paths; causes redefinitions.
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
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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>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Modules
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>eric@efcs.ca
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<th>CC</th>
<td>dgregor@apple.com, llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=17951" name="attach_17951" title="full reproducer.">attachment 17951</a> <a href="attachment.cgi?id=17951&action=edit" title="full reproducer.">[details]</a></span>
full reproducer.
Currently including "stddef.h" or other builtin headers when modules is enabled
causes Clang to find `module.modulemap` files along the wrong search paths. For
example, given the following configuration:
1) A project "my_project" which provides a module map for its headers.
2) The system has an installation of "my_project" in
"/usr/local/include/my_project".
3) A user has a local development copy of "my_project" that they are trying to
compile.
While compiling the local copy both the in-tree and system installed
module.modulemap are along the header include paths, however the local copy has
precedence and that's the module.modulemap Clang initially selects.
However after Clang processes a `#include "stddef.h"` it will end up processing
`/usr/local/include/my_project/module.modulemap`. This causes module
re-definition compile errors.
This bug is currently preventing LLVM from installing it's module maps, because
this bug will be hit when re-compiling LLVM.</pre>
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