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Hi all,</div>
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<br>
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For the code below, there is a undefined value assignment. However the report is incomplete, based on the report, we can't know where the undefined value came from.</div>
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<br>
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```</div>
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// clang -cc1 -analyze -analyzer-checker=core -analyzer-output=text test.c</div>
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void foo() {</div>
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char *argv[10];</div>
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const char* s = argv[2];</div>
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}</div>
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<br>
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// R<span style=" background-color: rgb(255, 255, 255); display: inline !important">eport information.</span></div>
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<br>
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<span>test.c:3:2: warning: Assigned value is garbage or undefined<br>
</span>
<div> const char *s = argv[2];<br>
</div>
<div> ^ ~~~~~~~<br>
</div>
<div>test.c:3:2: note: Assigned value is garbage or undefined<br>
</div>
<div> const char *s = argv[2];<br>
</div>
<div> ^ ~~~~~~~<br>
</div>
<span>1 warning generated.</span><br>
</div>
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```</div>
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The fix for this is not complex, adding the special hanle for `ArraySubscriptExpr` in `peelOffOuterExpr()` can achieve the goal.</div>
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```</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<span>static const Expr *peelOffOuterExpr(const Expr *Ex, </span><span>const ExplodedNode *N) {</span></div>
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// ...</div>
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<br>
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<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<span>if (auto *ASE = dyn_cast<ArraySubscriptExpr>(Ex))<br>
</span>
<div> return peelOffOuterExpr(ASE->getBase(), N);<br>
</div>
<span></span><br>
</div>
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// ...</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
}</div>
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```</div>
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<br>
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<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
However, After we modified `peelOffOuterExpr()`, another problem emerged at this time. Although we got the information where the undefined value came from, the description is not correct. </div>
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```</div>
<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
<span>test.c:3:2: warning: Assigned value is garbage or undefined<br>
</span>
<div> const char *s = argv[2];<br>
</div>
<div> ^ ~~~~~~~<br>
</div>
<div>test.c:2:2: note: 'argv' initialized here<br>
</div>
<div> char *argv[10];<br>
</div>
<div> ^~~~~~~~~~<br>
</div>
<div>test.c:3:2: note: Assigned value is garbage or undefined<br>
</div>
<div> const char *s = argv[2];<br>
</div>
<div> ^ ~~~~~~~<br>
</div>
<span>1 warning generated.</span><br>
</div>
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```</div>
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<br>
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<div style="font-family: Calibri, Helvetica, sans-serif; font-size: 12pt; color: rgb(0, 0, 0);">
The essential reason is that analyzer <span>treat </span><span>completely-undefined structures as defined values, see
<a href="http://clang-developers.42468.n3.nabble.com/uninitialized-variable-tp4053392p4053393.html" id="LPlnk313727">
http://clang-developers.42468.n3.nabble.com/uninitialized-variable-tp4053392p4053393.html</a>. That's why `showBRDiagnostics()` gave the wrong description.</span></div>
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uninitialized variable. I am writing a checker to check that a variable is given a value before it is accessed. So I created a checkLocation call-back: void checkLocation(SVal L, bool IsLoad, const...</div>
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I want to know if there is a simple and efficient way to determine whether the `LazyCompoundVal` is undefined or partially-undefined except iterating the `ElementRegion` bindings?</div>
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Thanks in advance!</div>
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<div style="font-family:Calibri,Helvetica,sans-serif; font-size:12pt; color:rgb(0,0,0)">
Henry Wong</div>
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Qihoo 360 Codesafe Team</div>
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