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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
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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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2 changes: 1 addition & 1 deletion test/testsymboldatabase.cpp
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Expand Up @@ -3633,7 +3633,7 @@ class TestSymbolDatabase : public TestFixture {
ASSERT(fredScope != nullptr);

// The struct Fred has two functions, a constructor and a destructor
ASSERT_EQUALS(2U, fredScope->functionList.size());
ASSERT_EQUALS(2U, fredScope->functionList.size()); // cppcheck-suppress nullPointer // see ticket #9747

@danmar danmar Oct 1, 2026

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This is an AI review. Take it with a grain of salt and feel free to reject it by resolving the comment.

I confirmed that this suppression is needed because of the PR. With selfcheck's options (--check-level=exhaustive --library=cppcheck-lib ...), the merge base gives no warning here, while this PR gives Possible null pointer dereference: fredScope. It is a false positive, since assert_() throws when the condition fails. The cause is that the removed "condition depends on only one variable" guard in setTokenValue() used to drop the nullptr from (it == db->scopeList.end()) ? nullptr : &*it, because the condition contains a function call. So user code with the same "ternary + throwing check" pattern will now also hit #9747.

To get a feel for how often that happens, I compared warnings for the merge base and the PR on lib/, cli/, test/cfg/, samples/, testsymboldatabase.cpp and testvalueflow.cpp (normal check level, style/warning/portability/performance, inconclusive). Both gave exactly the same 2407 warnings, so it doesn't look widespread. Some correlated-ternary probes such as d = (a > b) ? 0 : a - b; if (a > b) return 0; return 10 / d; also stayed silent. Just mentioning it so the trade-off is a conscious one.

@claude claude Bot Oct 10, 2026

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This suppression is only needed because of the valueflow change, so selfcheck now reports a new nullPointer false positive (after ASSERT(fredScope != nullptr)). I'd fix the regression rather than suppress it here. Users will hit the same pattern.


// Get linenumbers where the bodies for the constructor and destructor are..
unsigned int constructor = 0;
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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"
" 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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