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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Assertion failure in CXXNameMangler::mangleFunctionParam with typeid() of VLA"
href="http://llvm.org/bugs/show_bug.cgi?id=21632">21632</a>
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<th>Summary</th>
<td>Assertion failure in CXXNameMangler::mangleFunctionParam with typeid() of VLA
</td>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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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>
</tr>
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<th>Reporter</th>
<td>warren_ristow@playstation.sony.com
</td>
</tr>
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<th>CC</th>
<td>dgregor@apple.com, llvmbugs@cs.uiuc.edu
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>This is a low-priority issue.
When compiling the following test-case:
#include <typeinfo>
#include <stdio.h>
void foo(int i) {
char bar[i];
printf("%s\n", typeid(bar).name());
return;
}
with a Release+Asserts build of Clang, an assertion-failure triggers. A
Release (without Asserts) version compiles it successfully (and without any
warnings). FTR, in the Release version, 'typeid(bar).name()' returns "Afp__c",
whereas if (for example) the literal 17 had been used for the array (as in
'char bar[17];'), then it returns "A17_c". I've tested this with a modern
compiler (r222492), but the behavior appears to have existed for a long time.
The assertion-failure is:
clang: llvm/tools/clang/lib/AST/ItaniumMangle.cpp:3292:
void (anonymous namespace)::CXXNameMangler::mangleFunctionParam(const
clang::ParmVarDecl *):
Assertion `parmDepth < FunctionTypeDepth.getDepth()' failed.
Note that the test-case contains ill-formed C++ code. Specifically, the
typeid() of a Variable-Length array type is ill-formed. For reference, the
link:
<a href="http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3639.html">http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3639.html</a>
contains the following example, which explicitly has a typeid() of a VLA
indicated as being ill-formed:
void f(std::size_t n)
{
int a[n];
unsigned int x = sizeof(a); // ill-formed
const std::type_info& ti = typeid(a); // ill-formed
typedef int t[n]; // ill-formed
}
g++ considers this to be a user-error (tested with g++ version 4.8.2, but
probably is an error with all relevant versions of g++). Also tested with
other compilers, and it's considered a user-error. Likely, the Clang fix will
be to consider it a user-error, and then the ICE will be avoided.</pre>
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