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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - clang-cl: Come up with a way to do the equivalent of %INCLUDE% via command-line flags"
href="https://llvm.org/bugs/show_bug.cgi?id=26751">26751</a>
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<th>Summary</th>
<td>clang-cl: Come up with a way to do the equivalent of %INCLUDE% via command-line flags
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>PC
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<th>OS</th>
<td>Linux
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<th>Status</th>
<td>NEW
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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>Driver
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>nicolasweber@gmx.de
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>clang-cl currently supports a bunch of magic env vars, like cl.exe. Passing
things in env vars is messy (for example: if you want to use clang-cl on Linux,
should the env var item separator be : or ;?), so we should have the ability to
do the same with flags.
I thought just exposing -isystem and then passing one -isystem flag per INCLUDE
entry would be enough, but that's sadly not the case:
1. If I misspell the -isystem flag to point to a nonexistent directory, they're
ignored and the "real" system includes are still picked up. -nostdlibinc fixes
that, but clang-cl doesn't expose that. We could expose this flag too, seems
like a good and easy fix.
2. But even then, the -isystem flags are now searched before the built-in
headers, which has the effect of e.g. `#include <stddef.h>` picking up the msvs
header instead of clang's version (and now offsetof is no longer constexpr
etc). I guess one fix for this would be to add an explicit -isystem flag
pointing to clang's builtin header dir, but this is getting a bit ugly.
Does anyone happen to have better suggestions on how to get the exact same
effect as setting %INCLUDE% with flags?</pre>
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