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fix #2827 condition always false or true)

This commit is contained in:
Robert Reif 2011-07-16 22:06:23 -04:00
parent 35938e74ad
commit 430d22032d
3 changed files with 221 additions and 45 deletions
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175
lib/checkother.cpp
View File

@ -602,6 +602,9 @@ void CheckOther::checkAssignmentInAssert()
//---------------------------------------------------------------------------
// if ((x != 1) || (x != 3)) // <- always true
// if ((x == 1) && (x == 3)) // <- always false
// if ((x < 1) && (x > 3)) // <- always false
// if ((x > 3) || (x < 10)) // <- always true
//---------------------------------------------------------------------------
void CheckOther::checkIncorrectLogicOperator()
{
@ -617,71 +620,171 @@ void CheckOther::checkIncorrectLogicOperator()
// 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)))
const Token *op1Tok = NULL, *op2Tok = NULL, *op3Tok = NULL, *nextTok = NULL;
if (NULL != (logicTok = Token::findmatch(tok, "( %any% !=|==|<|> %any% ) &&|%oror% ( %any% !=|==|<|> %any% ) %any%", endTok)))
{
term1Tok = logicTok->next();
term2Tok = logicTok->tokAt(7);
op1Tok = logicTok->tokAt(2);
op2Tok = logicTok->tokAt(5);
op3Tok = logicTok->tokAt(8);
nextTok = logicTok->tokAt(11);
}
else if (NULL != (logicTok = Token::findmatch(tok, "%any% != %any% %oror% %any% != %any% !!&&", endTok)))
else if (NULL != (logicTok = Token::findmatch(tok, "%any% !=|==|<|> %any% &&|%oror% %any% !=|==|<|> %any% %any%", endTok)))
{
term1Tok = logicTok;
term2Tok = logicTok->tokAt(4);
op1Tok = logicTok->tokAt(1);
op2Tok = logicTok->tokAt(3);
op3Tok = logicTok->tokAt(5);
nextTok = logicTok->tokAt(7);
}
// The terms must not be AND'd with anything, to prevent false positives
if (logicTok && (logicTok->strAt(-1) != "&&"))
if (logicTok)
{
// Find the common variable and the two different-valued constants
unsigned int variableTested = 0;
std::string firstConstant, secondConstant;
if (Token::Match(term1Tok, "%var% != %num%"))
bool varFirst1, varFirst2;
unsigned int varId;
if (Token::Match(term1Tok, "%var% %any% %num%"))
{
const unsigned int varId = term1Tok->varId();
varId = term1Tok->varId();
if (!varId)
{
tok = Token::findmatch(endTok->next(), conditionPattern);
endTok = tok ? tok->next()->link() : NULL;
continue;
}
varFirst1 = true;
firstConstant = term1Tok->tokAt(2)->str();
if (Token::Match(term2Tok, "%varid% != %num%", varId))
{
variableTested = varId;
secondConstant = term2Tok->tokAt(2)->str();
}
else if (Token::Match(term2Tok, "%num% != %varid%", varId))
else if (Token::Match(term1Tok, "%num% %any% %var%"))
{
variableTested = varId;
secondConstant = term2Tok->str();
}
}
else if (Token::Match(term1Tok, "%num% != %var%"))
varId = term1Tok->tokAt(2)->varId();
if (!varId)
{
const unsigned int varId = term1Tok->tokAt(2)->varId();
tok = Token::findmatch(endTok->next(), conditionPattern);
endTok = tok ? tok->next()->link() : NULL;
continue;
}
varFirst1 = false;
firstConstant = term1Tok->str();
if (Token::Match(term2Tok, "%varid% != %num%", varId))
}
else
{
variableTested = varId;
tok = Token::findmatch(endTok->next(), conditionPattern);
endTok = tok ? tok->next()->link() : NULL;
continue;
}
if (Token::Match(term2Tok, "%var% %any% %num%"))
{
const unsigned int varId2 = term2Tok->varId();
if (!varId2 || varId != varId2)
{
tok = Token::findmatch(endTok->next(), conditionPattern);
endTok = tok ? tok->next()->link() : NULL;
continue;
}
varFirst2 = true;
secondConstant = term2Tok->tokAt(2)->str();
}
else if (Token::Match(term2Tok, "%num% != %varid%", varId))
{
variableTested = varId;
secondConstant = term2Tok->str();
}
else if (Token::Match(term2Tok, "%num% %any% %var%"))
{
const unsigned int varId2 = term1Tok->tokAt(2)->varId();
if (!varId2 || varId != varId2)
{
tok = Token::findmatch(endTok->next(), conditionPattern);
endTok = tok ? tok->next()->link() : NULL;
continue;
}
varFirst2 = false;
secondConstant = term2Tok->str();
variableTested = varId;
}
else
{
tok = Token::findmatch(endTok->next(), conditionPattern);
endTok = tok ? tok->next()->link() : NULL;
continue;
}
// 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)
if (variableTested == 0 || firstConstant.empty() || secondConstant.empty())
{
incorrectLogicOperatorError(term1Tok);
tok = Token::findmatch(endTok->next(), conditionPattern);
endTok = tok ? tok->next()->link() : NULL;
continue;
}
enum Position { First, Second, NA };
enum Relation { Equal, NotEqual, Less, LessEqual, More, MoreEqual };
struct Condition
{
const char *before;
bool beforeEqual;
Position position1;
const char *op1TokStr;
const char *op2TokStr;
Position position2;
const char *op3TokStr;
const char *after;
bool afterEqual;
Relation relation;
bool state;
} conditions[] =
{
{ "&&", false, NA, "!=", "||", NA, "!=", "&&", false, NotEqual, true }, // (x != 1) || (x != 3) <- always true
{ "(", true, NA, "==", "&&", NA, "==", ")", true, NotEqual, false }, // (x == 1) && (x == 3) <- always false
{ "(", true, First, "<", "&&", First, ">", ")", true, LessEqual, false }, // (x < 1) && (x > 3) <- always false
{ "(", true, First, ">", "&&", First, "<", ")", true, MoreEqual, false }, // (x > 3) && (x < 1) <- always false
{ "(", true, Second, ">", "&&", First, ">", ")", true, LessEqual, false }, // (1 > x) && (x > 3) <- always false
{ "(", true, First, ">", "&&", Second, ">", ")", true, MoreEqual, false }, // (x > 3) && (1 > x) <- always false
{ "(", true, First, "<", "&&", Second, "<", ")", true, LessEqual, false }, // (x < 1) && (3 < x) <- always false
{ "(", true, Second, "<", "&&", First, "<", ")", true, MoreEqual, false }, // (3 < x) && (x < 1) <- always false
{ "(", true, Second, ">", "&&", Second, "<", ")", true, LessEqual, false }, // (1 > x) && (3 < x) <- always false
{ "(", true, Second, "<", "&&", Second, ">", ")", true, MoreEqual, false }, // (3 < x) && (1 > x) <- always false
{ "(", true, First , ">", "||", First, "<", ")", true, More, true }, // (x > 3) || (x < 10) <- always true
{ "(", true, First , "<", "||", First, ">", ")", true, Less, true }, // (x < 10) || (x > 3) <- always true
{ "(", true, Second, "<", "||", First, "<", ")", true, More, true }, // (3 < x) || (x < 10) <- always true
{ "(", true, First, "<", "||", Second, "<", ")", true, Less, true }, // (x < 10) || (3 < x) <- always true
{ "(", true, First, ">", "||", Second, ">", ")", true, More, true }, // (x > 3) || (10 > x) <- always true
{ "(", true, Second, ">", "||", First, ">", ")", true, Less, true }, // (10 > x) || (x > 3) <- always true
{ "(", true, Second, "<", "||", Second, ">", ")", true, More, true }, // (3 < x) || (10 > x) <- always true
{ "(", true, Second, ">", "||", Second, "<", ")", true, Less, true }, // (10 > x) || (3 < x) <- always true
};
for (unsigned int i = 0; i < (sizeof(conditions) / sizeof(conditions[0])); i++)
{
if (!((conditions[i].position1 == NA) || (((conditions[i].position1 == First) && varFirst1) || ((conditions[i].position1 == Second) && !varFirst1))))
continue;
if (!((conditions[i].position2 == NA) || (((conditions[i].position2 == First) && varFirst2) || ((conditions[i].position2 == Second) && !varFirst2))))
continue;
if (op1Tok->str() != conditions[i].op1TokStr)
continue;
if (op2Tok->str() != conditions[i].op2TokStr)
continue;
if (op3Tok->str() != conditions[i].op3TokStr)
continue;
if (!((conditions[i].beforeEqual && (conditions[i].before == logicTok->strAt(-1))) || (!conditions[i].beforeEqual && (conditions[i].before != logicTok->strAt(-1)))))
continue;
if (!((conditions[i].afterEqual && (conditions[i].after == nextTok->str())) || (!conditions[i].afterEqual && (conditions[i].after != nextTok->str()))))
continue;
if ((conditions[i].relation == Equal && firstConstant == secondConstant) ||
(conditions[i].relation == NotEqual && firstConstant != secondConstant) ||
(conditions[i].relation == Less && firstConstant < secondConstant) ||
(conditions[i].relation == LessEqual && firstConstant <= secondConstant) ||
(conditions[i].relation == More && firstConstant > secondConstant) ||
(conditions[i].relation == MoreEqual && firstConstant >= secondConstant))
incorrectLogicOperatorError(term1Tok, conditions[i].state);
}
}
@ -3685,10 +3788,14 @@ void CheckOther::assignmentInAssertError(const Token *tok, const std::string &va
"builds this is a bug.");
}
void CheckOther::incorrectLogicOperatorError(const Token *tok)
void CheckOther::incorrectLogicOperatorError(const Token *tok, bool always)
{
if (always)
reportError(tok, Severity::warning,
"incorrectLogicOperator", "Mutual exclusion over || always evaluates to true. Did you intend to use && instead?");
else
reportError(tok, Severity::warning,
"incorrectLogicOperator", "Expression always evaluates to false. Did you intend to use || instead?");
}
void CheckOther::misusedScopeObjectError(const Token *tok, const std::string& varname)

4
lib/checkother.h
View File

@ -252,7 +252,7 @@ public:
void switchCaseFallThrough(const Token *tok);
void selfAssignmentError(const Token *tok, const std::string &varname);
void assignmentInAssertError(const Token *tok, const std::string &varname);
void incorrectLogicOperatorError(const Token *tok);
void incorrectLogicOperatorError(const Token *tok, bool always);
void misusedScopeObjectError(const Token *tok, const std::string &varname);
void catchExceptionByValueError(const Token *tok);
void memsetZeroBytesError(const Token *tok, const std::string &varname);
@ -299,7 +299,7 @@ public:
c.selfAssignmentError(0, "varname");
c.assignmentInAssertError(0, "varname");
c.invalidScanfError(0);
c.incorrectLogicOperatorError(0);
c.incorrectLogicOperatorError(0, true);
c.unusedVariableError(0, "varname");
c.allocatedButUnusedVariableError(0, "varname");
c.unreadVariableError(0, "varname");

73
test/testother.cpp
View File

@ -99,7 +99,10 @@ private:
TEST_CASE(trac2084);
TEST_CASE(assignmentInAssert);
TEST_CASE(incorrectLogicOperator);
TEST_CASE(incorrectLogicOperator1);
TEST_CASE(incorrectLogicOperator2);
TEST_CASE(catchExceptionByValue);
TEST_CASE(memsetZeroBytes);
@ -2018,7 +2021,7 @@ private:
ASSERT_EQUALS("[test.cpp:3]: (warning) Assert statement modifies 'a'.\n", errout.str());
}
void incorrectLogicOperator()
void incorrectLogicOperator1()
{
check("void f(int x) {\n"
" if ((x != 1) || (x != 3))\n"
@ -2126,6 +2129,72 @@ private:
ASSERT_EQUALS("", errout.str());
}
void incorrectLogicOperator2()
{
check("void f(int x) {\n"
" if ((x == 1) && (x == 3))\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (warning) Expression always evaluates to false. Did you intend to use || instead?\n", errout.str());
check("void f(int x) {\n"
" if (x == 1 && x == 3)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (warning) Expression always evaluates to false. Did you intend to use || instead?\n", errout.str());
check("void f(int x) {\n"
" if (x < 1 && x > 3)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (warning) Expression always evaluates to false. Did you intend to use || instead?\n", errout.str());
check("void f(int x) {\n"
" if (1 > x && 3 < x)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (warning) Expression always evaluates to false. Did you intend to use || instead?\n", errout.str());
check("void f(int x) {\n"
" if (x < 1 && x > 1)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (warning) Expression always evaluates to false. Did you intend to use || instead?\n", errout.str());
check("void f(int x) {\n"
" if (x < 3 && x > 1)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("", errout.str());
check("void f(int x) {\n"
" if (x > 3 || x < 10)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (warning) Mutual exclusion over || always evaluates to true. Did you intend to use && instead?\n", errout.str());
check("void f(int x) {\n"
" if (x > 3 || x < 3)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("", errout.str());
check("void f(int x) {\n"
" if (x > 10 || x < 3)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("", errout.str());
}
void catchExceptionByValue()
{
check("void f() {\n"