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Fix #11558 FP knownConditionTrueFalse when checking for zero character (#4794) 

* Fix #11558 FP knownConditionTrueFalse when checking for zero characte

* Fix test

* Set impossible value only for non-Boolean conditions, rename

* Fix condition
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chrchr-github 2023-02-18 17:35:12 +01:00 committed by GitHub
parent 1c11d3039d
commit ff0eee4d77
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2 changed files with 17 additions and 1 deletions
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8
lib/valueflow.cpp
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@ -5033,11 +5033,16 @@ static const Token* findIncompleteVar(const Token* start, const Token* end)
static ValueFlow::Value makeConditionValue(long long val,
const Token* condTok,
bool assume,
bool impossible = false,
const Settings* settings = nullptr,
SourceLocation loc = SourceLocation::current())
{
ValueFlow::Value v(val);
v.setKnown();
if (impossible) {
v.intvalue = !v.intvalue;
v.setImpossible();
}
v.condition = condTok;
if (assume)
v.errorPath.emplace_back(condTok, "Assuming condition '" + condTok->expressionString() + "' is true");
@ -5116,7 +5121,8 @@ static void valueFlowConditionExpressions(TokenList *tokenlist, SymbolDatabase*
{
for (const Token* condTok2 : getConditions(condTok, "&&")) {
if (is1) {
SameExpressionAnalyzer a1(condTok2, makeConditionValue(1, condTok2, true), tokenlist);
const bool isBool = astIsBool(condTok2) || Token::Match(condTok2, "%comp%|%oror%|&&");
SameExpressionAnalyzer a1(condTok2, makeConditionValue(1, condTok2, /*assume*/ true, !isBool), tokenlist); // don't set '1' for non-boolean expressions
valueFlowGenericForward(startTok, startTok->link(), a1, settings);
}

10
test/testcondition.cpp
View File

@ -4483,6 +4483,16 @@ private:
" g(s ? s->get() : 0);\n"
"}\n");
ASSERT_EQUALS("[test.cpp:5] -> [test.cpp:7]: (style) Condition 's' is always true\n", errout.str());
check("void f(const char* o) {\n" // #11558
" if (!o || !o[0])\n"
" return;\n"
" if (o[0] == '-' && o[1]) {\n"
" if (o[1] == '-') {}\n"
" if (o[1] == '\\0') {}\n"
" }\n"
"}\n");
ASSERT_EQUALS("[test.cpp:6]: (style) Condition 'o[1]=='\\0'' is always false\n", errout.str());
}
void alwaysTrueSymbolic()