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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Type mismatch for pointer to template template function"
href="https://bugs.llvm.org/show_bug.cgi?id=49079">49079</a>
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<th>Summary</th>
<td>Type mismatch for pointer to template template function
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>11.0
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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>Severity</th>
<td>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>C++17
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>pavel.kryukov@phystech.edu
</td>
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<th>CC</th>
<td>blitzrakete@gmail.com, erik.pilkington@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>If a function is a template template function (template<template<typename>
class> void foo(int&)), and a template template parameter has a default value,
it does not fit to function pointer type.
Example:
<span class="quote">> template<typename, typename = int> class A { };
>
> template<template<typename> class> void foo(int&);
> void bar(void(*)(int&));
>
> int main()
> {
> bar(foo<A>);
> }</span >
Output:
<span class="quote">> <source>:8:5: error: no matching function for call to 'bar'
> bar(foo<A>);
> ^~~
> <source>:4:6: note: candidate function not viable:
> no overload of 'foo' matching 'void (*)(int &)' for 1st argument
> void bar(void(*)(int&));</span >
Godbolt: <a href="https://godbolt.org/z/enhYs8">https://godbolt.org/z/enhYs8</a>
With GCC and MSVC, example compiles fine.</pre>
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