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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Feature: Add a warning when case labels from a different enum than the one in switch(EXPR) are used"
href="https://bugs.llvm.org/show_bug.cgi?id=39635">39635</a>
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<th>Summary</th>
<td>Feature: Add a warning when case labels from a different enum than the one in switch(EXPR) are used
</td>
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<th>Product</th>
<td>clang
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<th>Version</th>
<td>unspecified
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<th>Hardware</th>
<td>All
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<th>OS</th>
<td>All
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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>-New Bugs
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>avarab@gmail.com
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<th>CC</th>
<td>htmldeveloper@gmail.com, llvm-bugs@lists.llvm.org, richard-llvm@metafoo.co.uk
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<p>
<div>
<pre>I've filed this against GCC as well:
<a href="https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87983">https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87983</a>
A bug was fixed in git that would have been spotted by the following program
warning:
```
#include <stdio.h>
enum { A, B } foo = A;
enum { C, D } bar = C;
int main(void)
{
switch (foo) {
case C: /* Should warn: switch() on C instead of A */
puts("A");
break;
case B:
puts("B");
break;
}
}
```
I don't know how hard it would be to implement this. I understand why it's not
warning, in C enums are only skin-deep, so the compiler would need to keep
track of "foo" and the name (not just value) of C and B, and it wouldn't work
in the more general case of:
```
switch (some_complex_function(foo)) [...]
```</pre>
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