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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 - Clang uses >8GB of RAM to build a PCH for a simple header"
href="https://bugs.llvm.org/show_bug.cgi?id=41625">41625</a>
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<th>Summary</th>
<td>Clang uses >8GB of RAM to build a PCH for a simple header
</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>Linux
</td>
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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
</td>
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<th>Component</th>
<td>C++
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
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<th>Reporter</th>
<td>poletti.marco@gmail.com
</td>
</tr>
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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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<p>
<div>
<pre>Compiling a PCH for the following code:
struct Wrapper {
struct X {};
using Y = X(X(X(X(X(X(X(X(X(X(X(X(X(X(X(X())))))))))))))));
};
With a command like:
clang-8 -x c++-header file.h -o file.pch
Uses several GBs of RAM (>8).
If you want to reproduce, you might want to set a RAM limit in the current
shell, e.g. with "ulimit -Sv 8000000" otherwise your PC might start swapping
and/or become unresponsive.
I tested the following versions of Clang (on Ubuntu Linux):
8.0.0: affected
7.0.1: affected
6.0.1: NOT affected
So this seems to be a regression in Clang 7.x.
The above example is a minimized version of real code in
<a href="https://github.com/google/fruit">https://github.com/google/fruit</a>, where building PCHs now fails in Travis CI
with OOM errors.</pre>
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