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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - -Wshadow-ivar fires at point of use"
href="http://llvm.org/bugs/show_bug.cgi?id=16958">16958</a>
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<th>Summary</th>
<td>-Wshadow-ivar fires at point of use
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>Macintosh
</td>
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<th>OS</th>
<td>MacOS X
</td>
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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>
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<th>Component</th>
<td>Frontend
</td>
</tr>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>gwynne@darkrainfall.org
</td>
</tr>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>The warning controlled by -Wshadow-ivar (declaration shadows instance variable)
for Objective-C is issued at every instance where such the shadowing variable
is used, rather than at the point of the shadowing declaration. For example:
@interface A : NSObject
@end
@implementation A
{
NSString * __weak _str;
}
- (void)doSomethingHere
{
_Pragma("clang diagnostic push");
_Pragma("clang diagnostic ignored \"-Wshadow\"");
_Pragma("clang diagnostic ignored \"-Wshadow-ivar\"");
NSString * __strong _str = _str; // -Wshadow-ivar does not fire here
_Pragma("clang diagnostic pop");
NSLog(@"%@", _str); // -Wshadow-ivar DOES fire here
[self doSomethingElseWith:_str]; // -Wshadow-ivar fires again here
}
@end
This makes it impractical to deliberately shadow instance variables. A common
use case is temporarily taking a strong reference to a weak ivar, as in the
example given.</pre>
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</p>
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