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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Clang 10 disallows modifying const member by an unused member function in a templated class; while Clang 9 allows it"
href="https://bugs.llvm.org/show_bug.cgi?id=47789">47789</a>
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<th>Summary</th>
<td>Clang 10 disallows modifying const member by an unused member function in a templated class; while Clang 9 allows it
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>10.0
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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>enhancement
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>C++
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>jjkoshy@gmail.com
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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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<pre>Created <span class=""><a href="attachment.cgi?id=24042" name="attach_24042" title="Sample program demonstrating the issue">attachment 24042</a> <a href="attachment.cgi?id=24042&action=edit" title="Sample program demonstrating the issue">[details]</a></span>
Sample program demonstrating the issue
I'm not sure this is a bug or not.
- The sample program has a class template with a const member.
- A member function attempts to modify the member.
- The program does not actually use that member function
- Clang 9 and gcc compile the code fine, while clang 10 gives an error.
I see this behavior only with template classes, so I was thinking it may be a
case of SFINAE (in which case clang 10 should not be giving an error). However,
some others on cpplang slack are of the opinion this is a case of IFNDR, and
clang 10 is basically issuing eager diagnostics.
Code is here <a href="https://godbolt.org/z/r9sT44">https://godbolt.org/z/r9sT44</a>
and also attached to this report</pre>
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