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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Storing nullable values to local variables defeats -Wnullable-to-nonnull-conversion"
href="https://llvm.org/bugs/show_bug.cgi?id=30804">30804</a>
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<th>Summary</th>
<td>Storing nullable values to local variables defeats -Wnullable-to-nonnull-conversion
</td>
</tr>
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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>Macintosh
</td>
</tr>
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<th>OS</th>
<td>MacOS X
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Frontend
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>tjw@me.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=17499" name="attach_17499" title="sample case">attachment 17499</a> <a href="attachment.cgi?id=17499&action=edit" title="sample case">[details]</a></span>
sample case
Adding nullability annotations to ObjC source for correct interoperability with
Swift is made more difficult by the inability of clang to detect if a method
might return nil even if it says it doesn't.
clang apparently has a -Wnullable-to-nonnull-conversion flag to detect cases
like this. While it works for code like:
- (nonnull NSString *)ok:(nullable NSString *)arg;
{
return arg;
}
it is trivially confused by:
- (nonnull NSString *)bad:(nullable NSString *)arg;
{
// BAD: nullable value returned to a non-nullable result
NSString *result = arg;
return result;
}
Example file attached with a couple variants.</pre>
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