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Fixed #2162 (false positive: Mutual exclusion over ||)

This commit is contained in:
Zachary Blair 2010-11-21 00:06:43 -08:00
parent 1394d0245a
commit 215cb5ac8d
4 changed files with 57 additions and 27 deletions
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67
lib/checkother.cpp
View File

@ -220,10 +220,6 @@ void CheckOther::checkAssignmentInAssert()
//---------------------------------------------------------------------------
void CheckOther::checkIncorrectLogicOperator()
{
// Inconclusive until #2162 is fixed:
if (!_settings->inconclusive)
return;
if (!_settings->_checkCodingStyle)
return;
@ -234,6 +230,7 @@ void CheckOther::checkIncorrectLogicOperator()
while (tok && endTok)
{
// Find a pair of OR'd terms, with or without parenthesis
// e.g. if (x != 3 || x != 4)
const Token *logicTok = NULL, *term1Tok = NULL, *term2Tok = NULL;
if (NULL != (logicTok = Token::findmatch(tok, "( %any% != %any% ) %oror% ( %any% != %any% ) !!&&", endTok)))
{
@ -246,29 +243,55 @@ void CheckOther::checkIncorrectLogicOperator()
term2Tok = logicTok->tokAt(4);
}
// If both terms reference a common variable and are not AND'd with anything, this is an error
// The terms must not be AND'd with anything, to prevent false positives
if (logicTok && (logicTok->strAt(-1) != "&&"))
{
// (var11 != var12) || (var21 != var22)
const unsigned int varId11 = term1Tok->varId();
const unsigned int varId12 = term1Tok->tokAt(2)->varId();
const unsigned int varId21 = term2Tok->varId();
const unsigned int varId22 = term2Tok->tokAt(2)->varId();
// Find the common variable and the two different-valued constants
unsigned int variableTested = 0;
std::string firstConstant, secondConstant;
if (Token::Match(term1Tok, "%var% != %num%"))
{
const unsigned int varId = term1Tok->varId();
firstConstant = term1Tok->tokAt(2)->str();
// (var != const1) || (var != const2)
if (Token::Match(term1Tok, "%var%") &&
varId11 != 0 &&
(varId11 == varId21 || varId11 == varId22))
if (Token::Match(term2Tok, "%varid% != %num%", varId))
{
variableTested = varId;
secondConstant = term2Tok->tokAt(2)->str();
}
else if (Token::Match(term2Tok, "%num% != %varid%", varId))
{
variableTested = varId;
secondConstant = term2Tok->str();
}
}
else if (Token::Match(term1Tok, "%num% != %var%"))
{
const unsigned int varId = term1Tok->tokAt(2)->varId();
firstConstant = term1Tok->str();
if (Token::Match(term2Tok, "%varid% != %num%", varId))
{
variableTested = varId;
secondConstant = term2Tok->tokAt(2)->str();
}
else if (Token::Match(term2Tok, "%num% != %varid%", varId))
{
variableTested = varId;
secondConstant = term2Tok->str();
}
}
// If there is a common variable tested for inequality against
// either of two different-valued constants, then the expression
// will always evaluate to true and the || probably should be an &&
if (variableTested != 0 &&
!firstConstant.empty() &&
!secondConstant.empty() &&
firstConstant != secondConstant)
{
incorrectLogicOperatorError(term1Tok);
}
// (const1 != var) || (const2 != var)
else if (Token::Match(term1Tok->tokAt(2), "%var%") &&
varId12 != 0 &&
(varId12 == varId21 || varId12 == varId22))
{
incorrectLogicOperatorError(term1Tok->tokAt(2));
}
}
tok = Token::findmatch(endTok->next(), conditionPattern);
@ -2643,8 +2666,6 @@ void CheckOther::assignmentInAssertError(const Token *tok, const std::string &va
void CheckOther::incorrectLogicOperatorError(const Token *tok)
{
if (!_settings->inconclusive)
return;
reportError(tok, Severity::warning,
"incorrectLogicOperator", "Mutual exclusion over || always evaluates to true. Did you intend to use && instead?");
}

2
lib/checkother.h
View File

@ -251,7 +251,7 @@ public:
"* look for 'sizeof sizeof ..'\n"
"* look for calculations inside sizeof()\n"
"* assignment of a variable to itself\n"
//"* mutual exclusion over || always evaluating to true\n"
"* mutual exclusion over || always evaluating to true\n"
// optimisations
"* optimisation: detect post increment/decrement\n";

11
test/testother.cpp
View File

@ -104,7 +104,6 @@ private:
// Check..
Settings settings;
settings._checkCodingStyle = true;
settings.inconclusive = true;
CheckOther checkOther(&tokenizer, &settings, this);
// Clear the error buffer..
@ -1485,6 +1484,16 @@ private:
"}\n"
);
ASSERT_EQUALS("", errout.str());
check("void f(unsigned int a, unsigned int b, unsigned int c) {\n"
" if((a != b) || (c != b) || (c != a))\n"
" {\n"
" return true;\n"
" }\n"
" return false;\n"
"}\n"
);
ASSERT_EQUALS("", errout.str());
}
};