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Fixed #9363 (knownConditionTrueFalse: False positive about function parameter)

This commit is contained in:
Daniel Marjamäki 2019-10-31 08:32:39 +01:00
parent 7c2c81bf41
commit 9094ff01d3
2 changed files with 32 additions and 51 deletions
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56
lib/checkcondition.cpp
View File

@ -1333,11 +1333,28 @@ void CheckCondition::alwaysTrueFalse()
const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
for (const Scope * scope : symbolDatabase->functionScopes) {
for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) {
if (tok->link()) // don't write false positives when templates are used
continue;
if (!tok->hasKnownIntValue())
continue;
{
// is this a condition..
const Token *parent = tok->astParent();
while (Token::Match(parent, "%oror%|&&"))
parent = parent->astParent();
if (!parent)
continue;
const Token *condition = nullptr;
if (parent->str() == "?" && precedes(tok, parent))
condition = parent->astOperand1();
else if (Token::Match(parent->previous(), "if|while ("))
condition = parent->astOperand2();
else if (parent->str() == ";" && parent->astParent() && parent->astParent()->astParent() && Token::simpleMatch(parent->astParent()->astParent()->previous(), "for ("))
condition = parent->astOperand1();
else
continue;
(void)condition;
}
// Skip already diagnosed values
if (diag(tok, false))
continue;
@ -1355,38 +1372,9 @@ void CheckCondition::alwaysTrueFalse()
(Token::Match(tok->astParent(), "%oror%|&&") || Token::Match(tok->astParent()->astOperand1(), "if|while"));
const bool constValExpr = tok->isNumber() && Token::Match(tok->astParent(),"%oror%|&&|?"); // just one number in boolean expression
const bool compExpr = Token::Match(tok, "%comp%|!"); // a compare expression
const bool returnStatement = Token::simpleMatch(tok->astTop(), "return") &&
Token::Match(tok->astParent(), "%oror%|&&|return");
const bool ternaryExpression = Token::simpleMatch(tok->astParent(), "?");
if (!(constIfWhileExpression || constValExpr || compExpr || returnStatement || ternaryExpression))
continue;
if (returnStatement && (!scope->function || !Token::simpleMatch(scope->function->retDef, "bool")))
continue;
if (returnStatement && isConstVarExpression(tok))
continue;
if (returnStatement && Token::simpleMatch(tok->astParent(), "return") && tok->variable() && (
!tok->variable()->isLocal() ||
tok->variable()->isReference() ||
tok->variable()->isConst() ||
!isVariableChanged(tok->variable(), mSettings, mTokenizer->isCPP())))
continue;
// Don't warn in assertions. Condition is often 'always true' by intention.
// If platform,defines,etc cause 'always false' then that is not dangerous neither.
bool assertFound = false;
for (const Token * tok2 = tok->astParent(); tok2 ; tok2 = tok2->astParent()) { // move backwards and try to find "assert"
if (tok2->str() == "(" && tok2->astOperand2()) {
const std::string& str = tok2->previous()->str();
if ((str.find("assert")!=std::string::npos || str.find("ASSERT")!=std::string::npos))
assertFound = true;
break;
}
}
if (assertFound)
if (!(constIfWhileExpression || constValExpr || compExpr || ternaryExpression))
continue;
// Don't warn when there are expanded macros..
@ -1446,15 +1434,15 @@ void CheckCondition::alwaysTrueFalse()
void CheckCondition::alwaysTrueFalseError(const Token *tok, const ValueFlow::Value *value)
{
const bool condvalue = value && (value->intvalue != 0);
const bool alwaysTrue = value && (value->intvalue != 0);
const std::string expr = tok ? tok->expressionString() : std::string("x");
const std::string errmsg = "Condition '" + expr + "' is always " + (condvalue ? "true" : "false");
const std::string errmsg = "Condition '" + expr + "' is always " + (alwaysTrue ? "true" : "false");
const ErrorPath errorPath = getErrorPath(tok, value, errmsg);
reportError(errorPath,
Severity::style,
"knownConditionTrueFalse",
errmsg,
(condvalue ? CWE571 : CWE570), false);
(alwaysTrue ? CWE571 : CWE570), false);
}
void CheckCondition::checkInvalidTestForOverflow()

27
test/testcondition.cpp
View File

@ -2681,8 +2681,7 @@ private:
"}");
ASSERT_EQUALS("[test.cpp:2]: (style) Suspicious condition (bitwise operator + comparison); Clarify expression with parentheses.\n"
"[test.cpp:2]: (style) Boolean result is used in bitwise operation. Clarify expression with parentheses.\n"
"[test.cpp:2]: (style) Condition 'x&3==2' is always false\n"
"[test.cpp:2]: (style) Condition '3==2' is always false\n", errout.str());
"[test.cpp:2]: (style) Condition 'x&3==2' is always false\n", errout.str());
check("void f() {\n"
" if (a & fred1.x == fred2.y) {}\n"
@ -2834,21 +2833,6 @@ private:
"}");
ASSERT_EQUALS("[test.cpp:4]: (style) Condition '!x' is always true\n", errout.str());
check("bool f(int x) {\n"
" if(x == 0) { x++; return x == 0; } \n"
" return false;\n"
"}");
ASSERT_EQUALS("[test.cpp:2] -> [test.cpp:2]: (style) Condition 'x==0' is always false\n", errout.str());
check("void f() {\n" // #6898 (Token::expressionString)
" int x = 0;\n"
" A(x++ == 1);\n"
" A(x++ == 2);\n"
"}");
ASSERT_EQUALS("[test.cpp:3]: (style) Condition 'x++==1' is always false\n"
"[test.cpp:4]: (style) Condition 'x++==2' is always false\n",
errout.str());
check("void f1(const std::string &s) { if(s.empty()) if(s.size() == 0) {}} ");
ASSERT_EQUALS("[test.cpp:1] -> [test.cpp:1]: (style) Condition 's.size()==0' is always true\n", errout.str());
@ -2953,6 +2937,15 @@ private:
"}");
ASSERT_EQUALS("", errout.str());
// #9363 - do not warn about value passed to function
check("void f(bool b) {\n"
" if (b) {\n"
" if (bar(!b)) {}\n"
" }\n"
"}\n");
ASSERT_EQUALS("", errout.str());
// #7783 FP knownConditionTrueFalse on assert(0 && "message")
check("void foo(int x) {\n"
" if (x<0)\n"