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Fix #15034 FN arrayIndexOutOfBounds (ternary in subfunction) #8856

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Fix #15034 FN arrayIndexOutOfBounds (ternary in subfunction) #8856

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50b9a36
Update valueflow.cpp
chrchr-github Sep 15, 2026
67eb159
Update vf_settokenvalue.cpp
chrchr-github Sep 15, 2026
86f316f
Update testvalueflow.cpp
chrchr-github Sep 15, 2026
55d8250
Update testvalueflow.cpp
chrchr-github Sep 15, 2026
1406a57
Update testsymboldatabase.cpp
chrchr-github Sep 15, 2026
bbd2441
Merge branch 'main' into chr_15034
chrchr-github Oct 1, 2026
72fa075
Merge branch 'main' into chr_15034
chrchr-github Oct 10, 2026
c9716c6
Update testvalueflow.cpp
chrchr-github Oct 13, 2026
dff6214
Update vf_settokenvalue.cpp
chrchr-github Oct 13, 2026
7ae3a34
Update testsymboldatabase.cpp
chrchr-github Oct 14, 2026
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3 changes: 2 additions & 1 deletion lib/valueflow.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -5164,8 +5164,9 @@ static void valueFlowInferCondition(TokenList& tokenlist, const Settings& settin
setTokenValue(tok, std::move(value), settings);
}
}
} else if (Token::Match(tok->astParent(), "?|&&|!|%oror%") ||
} else if (Token::Match(tok->astParent(), "&&|!|%oror%") ||
Token::Match(tok->astParent()->previous(), "if|while (") ||
(astIsLHS(tok) && Token::simpleMatch(tok->astParent(), "?")) ||
((astIsPointer(tok) || tok->function()) && isUsedAsBool(tok, settings))) {
std::vector<ValueFlow::Value> result = infer(makeIntegralInferModel(), "!=", tok->values(), 0);
if (result.size() != 1)
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3 changes: 1 addition & 2 deletions lib/vf_settokenvalue.cpp
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Expand Up @@ -434,7 +434,7 @@ namespace ValueFlow
visitAstNodes(parent->astOperand1(),
[&](const Token *t) {
if (t->varId()) {
if (varId > 0 || value.varId != 0)
if (varId > 0)
ret = true;
varId = t->varId();
} else if (t->str() == "(" && Token::Match(t->previous(), "%name%"))
Expand All @@ -443,7 +443,6 @@ namespace ValueFlow
});
if (ret)
return;

value.conditional = true;
value.changeKnownToPossible();

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39 changes: 39 additions & 0 deletions test/testvalueflow.cpp
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Expand Up @@ -4325,6 +4325,45 @@ class TestValueFlow : public TestFixture {
"}\n";
auto values = tokenValues(code, "s :", ValueFlow::Value::ValueType::FLOAT);
ASSERT_EQUALS(0, values.size());

code = "int a[5];\n" // 15034
"int g(int i) {\n"
" return a[i < 0 ? -i : i];\n"
"}\n"
"int f() {\n"
" return g(-5);\n"
"}\n";
values = tokenValues(code, "?");
ASSERT_EQUALS(2, values.size());
auto it = values.begin();
ASSERT_EQUALS_ENUM(ValueFlow::Value::ValueType::INT, it->valueType);
ASSERT_EQUALS(0, it->intvalue);
ASSERT_EQUALS_ENUM(ValueFlow::Value::Bound::Lower, it->bound);
ASSERT_EQUALS_ENUM(ValueFlow::Value::ValueKind::Possible, it->valueKind);
++it;
ASSERT_EQUALS_ENUM(ValueFlow::Value::ValueType::INT, it->valueType);
ASSERT_EQUALS(5, it->intvalue);
ASSERT_EQUALS_ENUM(ValueFlow::Value::Bound::Point, it->bound);
ASSERT_EQUALS_ENUM(ValueFlow::Value::ValueKind::Possible, it->valueKind);

@claude claude Bot Oct 10, 2026

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The ticket is about an arrayIndexOutOfBounds false negative, but there's no checker-level test for it. Please add the ticket example to testbufferoverrun.cpp, together with a negative case such as a[i < 0 ? 0 : i] called with g(-5), which must not warn.


code = "int f(int a, int b) {\n"
" if (b <= 0)\n"
" return b;\n"
" int a = (a > 0) ? a : -a;\n"

@dmcppcheck dmcppcheck Oct 15, 2026

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AI review

This snippet isn't valid C/C++: int a = (a > 0) ? a : -a; redeclares the parameter a in the function's outermost block, and it initialises a from itself. Running cppcheck on it gives legacyUninitvar on line 4. Please use a fresh variable, e.g. int c = (a > 0) ? a : -a; return 1 / (c < b ? b : c);, which gives the same value-flow shape.

Also, the two values below are asserted with identical fields (SYMBOLIC, -1, Upper, Impossible), and it->tokvalue is never checked. That means the test can't tell the !<=symbolic=(a-1) value from the !<=symbolic=(b-1) value. Checking the symbol, e.g. ASSERT_EQUALS("b", it->tokvalue->expressionString()), or using isImpossibleContainerSizeValue-style helpers would make the test pin down the intended behaviour.

" return 1 / (a < b ? b : a);\n"
"}\n";
values = tokenValues(code, "? b");
ASSERT_EQUALS(2, values.size());
it = values.begin();
ASSERT_EQUALS_ENUM(ValueFlow::Value::ValueType::SYMBOLIC, it->valueType);
ASSERT_EQUALS(-1, it->intvalue);
ASSERT_EQUALS_ENUM(ValueFlow::Value::Bound::Upper, it->bound);
ASSERT_EQUALS_ENUM(ValueFlow::Value::ValueKind::Impossible, it->valueKind);
++it;
ASSERT_EQUALS_ENUM(ValueFlow::Value::ValueType::SYMBOLIC, it->valueType);
ASSERT_EQUALS(-1, it->intvalue);
ASSERT_EQUALS_ENUM(ValueFlow::Value::Bound::Upper, it->bound);
ASSERT_EQUALS_ENUM(ValueFlow::Value::ValueKind::Impossible, it->valueKind);
}

void valueFlowForwardLambda() {
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