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Fix #14392 FN knownConditionTrueFalse (assigning function call result) #8118

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Fix #14392 FN knownConditionTrueFalse (assigning function call result) #8118

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e93fb9c
Update checkcondition.cpp
chrchr-github Jan 13, 2026
0faaf14
Update testcondition.cpp
chrchr-github Jan 13, 2026
8dc1bd6
Update checkcondition.cpp
chrchr-github Jan 13, 2026
5a1aa4f
Update .selfcheck_suppressions
chrchr-github Jan 13, 2026
e5f529a
Update checkcondition.cpp
chrchr-github Jan 15, 2026
48b66db
Update testcondition.cpp
chrchr-github Jan 15, 2026
73a4900
Update checkcondition.cpp
chrchr-github Jan 15, 2026
4551f97
Update testcondition.cpp
chrchr-github Jan 15, 2026
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1 change: 1 addition & 0 deletions .selfcheck_suppressions
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Original file line number Diff line number Diff line change
Expand Up @@ -40,5 +40,6 @@ naming-privateMemberVariable:externals/tinyxml2/tinyxml2.h
functionStatic:externals/tinyxml2/tinyxml2.cpp
funcArgNamesDifferent:externals/tinyxml2/tinyxml2.cpp
nullPointerRedundantCheck:externals/tinyxml2/tinyxml2.cpp
knownConditionTrueFalse:externals/tinyxml2/tinyxml2.cpp
useStlAlgorithm:externals/simplecpp/simplecpp.cpp
missingMemberCopy:externals/simplecpp/simplecpp.h
13 changes: 12 additions & 1 deletion lib/checkcondition.cpp
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Expand Up @@ -1545,6 +1545,8 @@ void CheckCondition::alwaysTrueFalse()
condition = parent->astParent()->astParent()->previous();
else if (Token::Match(tok, "%comp%"))
condition = tok;
else if (tok->str() == "(" && astIsBool(parent) && Token::Match(parent, "%assign%"))
condition = tok;
else
continue;
}
Expand Down Expand Up @@ -1647,11 +1649,20 @@ void CheckCondition::alwaysTrueFalse()
}
}

static std::string getConditionString(const Token* condition)
{
if (Token::simpleMatch(condition, "return"))
return "Return value";
if (Token::simpleMatch(condition, "(") && Token::Match(condition->astParent(), "%assign%"))
return "Assigned value";
return "Condition";
}

void CheckCondition::alwaysTrueFalseError(const Token* tok, const Token* condition, const ValueFlow::Value* value)
{
const bool alwaysTrue = value && (value->intvalue != 0 || value->isImpossible());
const std::string expr = tok ? tok->expressionString() : std::string("x");
const std::string conditionStr = (Token::simpleMatch(condition, "return") ? "Return value" : "Condition");
const std::string conditionStr = getConditionString(condition);
const std::string errmsg = conditionStr + " '" + expr + "' is always " + bool_to_string(alwaysTrue);
ErrorPath errorPath = getErrorPath(tok, value, errmsg);
reportError(std::move(errorPath),
Expand Down
13 changes: 13 additions & 0 deletions test/testcondition.cpp
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Expand Up @@ -4787,6 +4787,19 @@ class TestCondition : public TestFixture {
" }\n"
"}\n");
ASSERT_EQUALS("", errout_str());

check("struct S {\n" // #14392
" bool g() const { return m; }\n"
" bool m{};\n"
"};\n"
"bool f(S s) {\n"
" if (s.g()) {\n"
" bool b = s.g();\n"
" return b;\n"
" }\n"
" return false;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:6:12] -> [test.cpp:7:21]: (style) Assigned value 's.g()' is always true [knownConditionTrueFalse]\n", errout_str());
}

void alwaysTrueSymbolic()
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