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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - -Wshadow should ignore variables declared and shadowed in macros"
href="http://llvm.org/bugs/show_bug.cgi?id=18712">18712</a>
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<th>Summary</th>
<td>-Wshadow should ignore variables declared and shadowed in macros
</td>
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<th>Product</th>
<td>clang
</td>
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<th>Version</th>
<td>3.4
</td>
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<th>Hardware</th>
<td>Other
</td>
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<th>OS</th>
<td>Linux
</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>-New Bugs
</td>
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<th>Assignee</th>
<td>unassignedclangbugs@nondot.org
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<th>Reporter</th>
<td>htam@apple.com
</td>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
</td>
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<th>Classification</th>
<td>Unclassified
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<p>
<div>
<pre>I get many false positives from -Wshadow for variables that are used by some
macros that are then nested into each other. -Wshadow should ignore the case
where a variable is only used by a macro expansion.
$ cat foo.c
#include <stdio.h>
#define BAD_EXAMPLE(n) \
{ \
int __increment = 0; \
while (__increment < n) {
#define WORSE \
} \
__increment += 1; \
}
void foo(void) {
BAD_EXAMPLE(100) {
BAD_EXAMPLE(5) {
puts("hi");
} WORSE;
} WORSE;
}
$ clang foo.c -c -o /dev/null -Wshadow
foo.c:15:9: warning: declaration shadows a local variable [-Wshadow]
BAD_EXAMPLE(5) {
^
foo.c:5:13: note: expanded from macro 'BAD_EXAMPLE'
int __increment = 0; \
^
foo.c:14:5: note: previous declaration is here
BAD_EXAMPLE(100) {
^
foo.c:5:13: note: expanded from macro 'BAD_EXAMPLE'
int __increment = 0; \
^
1 warning generated.</pre>
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