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Fix #8260 Improve check: Pointer calculation result not null #8061

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Fix #8260 Improve check: Pointer calculation result not null #8061

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6c5d17b
Fix #8260 Improve check: Pointer calculation result not null
francois-berder Dec 26, 2025
a455bb2
fixup! Fix #8260 Improve check: Pointer calculation result not null
francois-berder Dec 26, 2025
4b1135d
fixup! fixup! Fix #8260 Improve check: Pointer calculation result no…
francois-berder Dec 26, 2025
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30 changes: 27 additions & 3 deletions lib/checkcondition.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1782,15 +1782,39 @@ void CheckCondition::checkPointerAdditionResultNotNull()
if (tok->isExpandedMacro())
continue;

const Token *calcToken, *exprToken;
const Token *calcToken = nullptr, *exprToken = nullptr;
if (tok->astOperand1()->str() == "+") {
calcToken = tok->astOperand1();
exprToken = tok->astOperand2();
} else if (tok->astOperand2()->str() == "+") {
calcToken = tok->astOperand2();
exprToken = tok->astOperand1();
} else
continue;
} else {
const Token *pointerToken = nullptr;
if (tok->astOperand1()->variable() && tok->astOperand1()->variable()->isPointer())
pointerToken = tok->astOperand1();
else if (tok->astOperand2()->variable() && tok->astOperand2()->variable()->isPointer())
pointerToken = tok->astOperand2();

if (!pointerToken)
continue;

const std::list<ValueFlow::Value> &tokenValues = pointerToken->values();
for (const ValueFlow::Value &val : tokenValues) {
if (val.isSymbolicValue()) {
if (val.tokvalue->str() == "+") {
calcToken = val.tokvalue;
if (pointerToken == tok->astOperand1())
exprToken = tok->astOperand2();
else
exprToken = tok->astOperand1();
break;
}
}
}
if (!calcToken || !exprToken)
continue;
}

// pointer comparison against NULL (ptr+12==0)
if (calcToken->hasKnownIntValue())
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12 changes: 12 additions & 0 deletions test/testcondition.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6026,6 +6026,18 @@ class TestCondition : public TestFixture {
" if (ptr + 1 != 0);\n"
"}");
ASSERT_EQUALS("[test.cpp:2:15]: (warning) Comparison is wrong. Result of 'ptr+1' can't be 0 unless there is pointer overflow, and pointer overflow is undefined behaviour. [pointerAdditionResultNotNull]\n", errout_str());

// #8260
check("void f(int *p) {\n"
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@chrchr-github chrchr-github Dec 27, 2025

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Is it worth adding a test for the original example from #8260?

" int * q = p + 1;\n"
" if (q != 0);\n"
"}");
ASSERT_EQUALS("[test.cpp:3:9]: (warning) Comparison is wrong. Result of 'p+1' can't be 0 unless there is pointer overflow, and pointer overflow is undefined behaviour. [pointerAdditionResultNotNull]\n", errout_str());
check("void f(int *p) {\n"
" int * q = p + 1;\n"
" if (0 != q);\n"
"}");
ASSERT_EQUALS("[test.cpp:3:9]: (warning) Comparison is wrong. Result of 'p+1' can't be 0 unless there is pointer overflow, and pointer overflow is undefined behaviour. [pointerAdditionResultNotNull]\n", errout_str());
}

void duplicateConditionalAssign() {
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