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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 does not match GCC re: instantiation-dependent expressions in mangling"
href="https://bugs.llvm.org/show_bug.cgi?id=52191">52191</a>
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<th>Summary</th>
<td>Clang does not match GCC re: instantiation-dependent expressions in mangling
</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>All
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Keywords</th>
<td>ABI
</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>hstong@ca.ibm.com
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<th>CC</th>
<td>arthur.j.odwyer@gmail.com, 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>As noted by Arthur O'Dwyer in <a class="bz_bug_link
bz_status_RESOLVED bz_closed"
title="RESOLVED FIXED - Invalid subexpression in sizeof fails to remove candidate"
href="show_bug.cgi?id=28667">bug 28667</a>, Clang does not mangle
instantiation-dependent (but neither type nor value dependent) expressions as
GCC does.
For example, given:
struct A { A(int); };
template <typename T> void foo(int, char (*)[sizeof(0, A(T()))]) { }
template <typename T> void foo(int, ...);
int main(void) {
foo<decltype(nullptr)>(0, 0);
foo<int>(0, 0);
}
The sizeof expression is instantiation-dependent: substitution with nullptr_t
fails.
Clang mangles the `int` specialization as `_Z3fooIiEviPA1_c` (i.e., `void
foo<int>(int, char (*) [1])`). GCC mangles it as
`_Z3fooIiEviPAszcmLi0Ecv1AcvT__E_c` (i.e., `void foo<int>(int, char (*) [sizeof
((0),((A)((int)())))])`).
Online compiler: <a href="https://gcc.godbolt.org/z/exj1onseW">https://gcc.godbolt.org/z/exj1onseW</a></pre>
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