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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Could warn for more uses of null pointer"
href="https://bugs.llvm.org/show_bug.cgi?id=45238">45238</a>
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<th>Summary</th>
<td>Could warn for more uses of null pointer
</td>
</tr>
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<th>Product</th>
<td>clang
</td>
</tr>
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<th>Version</th>
<td>unspecified
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<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>
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<th>Reporter</th>
<td>john.brawn@arm.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, neeilans@live.com, richard-llvm@metafoo.co.uk
</td>
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<p>
<div>
<pre>For the following functions:
int fn1() {
int *var;
return *var;
}
int fn2() {
int *var = 0;
return *var;
}
int fn3() {
return *(int*)0;
}
With -Wall we give a warning for fn1 and fn3, but not fn2:
tmp.c:3:11: warning: variable 'var' is uninitialized when used here
[-Wuninitialized]
return *var;
^~~
tmp.c:2:11: note: initialize the variable 'var' to silence this warning
int *var;
^
= 0
tmp.c:10:10: warning: indirection of non-volatile null pointer will be deleted,
not trap [-Wnull-dereference]
return *(int*)0;
^~~~~~~~
tmp.c:10:10: note: consider using __builtin_trap() or qualifying pointer with
'volatile'
It looks like we should be able to warn for fn2 as well, given that we can warn
for use of var when it's uninitialized.</pre>
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</p>
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