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Fix #14535: false positive: unreadVariable (array access after pointer cast) #8324

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Fix #14535: false positive: unreadVariable (array access after pointer cast) #8324

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388afe6
Add test
ludviggunne Mar 11, 2026
c9588f2
Fix #14353
ludviggunne Mar 11, 2026
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32 changes: 19 additions & 13 deletions lib/astutils.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3670,21 +3670,27 @@ bool isGlobalData(const Token *expr)
globalData = true;
return ChildrenToVisit::none;
}
if (Token::Match(tok, "[*[]") && tok->astOperand1() && tok->astOperand1()->variable()) {
if (Token::Match(tok, "[*[]") && tok->astOperand1()) {
// TODO check if pointer points at local data
const Variable *lhsvar = tok->astOperand1()->variable();
const ValueType *lhstype = tok->astOperand1()->valueType();
if (lhsvar->isPointer() || !lhstype || lhstype->type == ValueType::Type::ITERATOR) {
globalData = true;
return ChildrenToVisit::none;
}
if (lhsvar->isArgument() && lhsvar->isArray()) {
globalData = true;
return ChildrenToVisit::none;
const Token *lhs = tok->astOperand1();
if (!lhs->variable() && Token::Match(lhs, "( %type%")) {
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@chrchr-github chrchr-github Mar 11, 2026

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It's probably better to check lhs->isCast() && !lhs->astOperand2(). That should also handle (::Type).

lhs = lhs->astOperand1();
}
if (lhsvar->isArgument() && lhstype->type <= ValueType::Type::VOID && !lhstype->container) {
globalData = true;
return ChildrenToVisit::none;
if (lhs && lhs->variable()) {
const Variable *lhsvar = lhs->variable();
const ValueType *lhstype = lhs->valueType();
if (lhsvar->isPointer() || !lhstype || lhstype->type == ValueType::Type::ITERATOR) {
globalData = true;
return ChildrenToVisit::none;
}
if (lhsvar->isArgument() && lhsvar->isArray()) {
globalData = true;
return ChildrenToVisit::none;
}
if (lhsvar->isArgument() && lhstype->type <= ValueType::Type::VOID && !lhstype->container) {
globalData = true;
return ChildrenToVisit::none;
}
}
}
if (tok->varId() == 0 && tok->isName() && tok->strAt(-1) != ".") {
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11 changes: 11 additions & 0 deletions test/testunusedvar.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -271,6 +271,8 @@ class TestUnusedVar : public TestFixture {
TEST_CASE(globalData);

TEST_CASE(structuredBinding); // #13269

TEST_CASE(pointerCast); // #14535
}

struct FunctionVariableUsageOptions
Expand Down Expand Up @@ -7308,6 +7310,15 @@ class TestUnusedVar : public TestFixture {
"}\n");
ASSERT_EQUALS("", errout_str());
}

void pointerCast() { // #14535
functionVariableUsage("void f(int* p)\n"
"{\n"
" int* p2 = p;\n"
" ((int *)(p2))[0] = 0; // remove cast for warning to disappear\n"
"}\n");
ASSERT_EQUALS("", errout_str());
}
};

REGISTER_TEST(TestUnusedVar)
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