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Fix #14005 FP: returnDanglingLifetime while returning reference to struct field #7661

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Merged
chrchr-github merged 4 commits into from
Jul 12, 2025
Merged

Fix #14005 FP: returnDanglingLifetime while returning reference to struct field #7661

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9778fd2
Fix #14005 FP: returnDanglingLifetime while returning reference to s…
web-flow Jul 10, 2025
ece8678
Update valueflow.cpp
chrchr-github Jul 10, 2025
8df5f3b
Update testautovariables.cpp
chrchr-github Jul 11, 2025
e412c1f
Fix FN
web-flow Jul 11, 2025
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8 changes: 8 additions & 0 deletions lib/valueflow.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3119,6 +3119,14 @@ static void valueFlowLifetime(TokenList &tokenlist, ErrorLogger &errorLogger, co
else if (tok->isUnaryOp("&")) {
if (Token::simpleMatch(tok->astParent(), "*"))
continue;
if (Token::simpleMatch(tok->astOperand1(), "[")) {
const Token* const op1 = tok->astOperand1()->astOperand1();
const Token* tok2 = op1;
while (Token::simpleMatch(tok2, "."))
tok2 = tok2->astOperand2();
if (tok2 && tok2 != op1 && (!tok2->variable() || !tok2->variable()->isArray()) && !(tok2->valueType() && tok2->valueType()->container))
continue;
}
for (const ValueFlow::LifetimeToken& lt : ValueFlow::getLifetimeTokens(tok->astOperand1(), settings)) {
if (!settings.certainty.isEnabled(Certainty::inconclusive) && lt.inconclusive)
continue;
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21 changes: 21 additions & 0 deletions test/testautovariables.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,7 @@ class TestAutoVariables : public TestFixture {
TEST_CASE(testautovar_return3);
TEST_CASE(testautovar_return4);
TEST_CASE(testautovar_return5);
TEST_CASE(testautovar_return6);
TEST_CASE(testautovar_extern);
TEST_CASE(testautovar_reassigned);
TEST_CASE(testinvaliddealloc);
Expand Down Expand Up @@ -624,6 +625,26 @@ class TestAutoVariables : public TestFixture {
ASSERT_EQUALS("", errout_str());
}

void testautovar_return6() { // #14005
check("struct S;\n"
"struct T { const struct S *s; };\n"
"extern struct T factory();\n"
"const struct S* f() {\n"
" struct T t = factory();\n"
" return &t.s[0];\n"
"}\n");
ASSERT_EQUALS("", errout_str());

check("struct S;\n"
"struct T { std::vector<struct S> v; };\n"
"extern struct T factory();\n"
"const struct S* f() {\n"
" struct T t = factory();\n"
" return &t.v[0];\n"
"}\n");
ASSERT_EQUALS("[test.cpp:6:12] -> [test.cpp:5:14] -> [test.cpp:6:12]: (error) Returning pointer to local variable 't' that will be invalid when returning. [returnDanglingLifetime]\n", errout_str());
}

void testautovar_extern() {
check("struct foo *f()\n"
"{\n"
Expand Down