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fix #3011 (new check: when first comparison is true, the 2nd comparison is always true)

This commit is contained in:
Robert Reif 2011-08-19 13:28:37 -04:00
parent a735790e77
commit 9fbef3ca7b
3 changed files with 179 additions and 27 deletions
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88
lib/checkother.cpp
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@ -748,10 +748,20 @@ void CheckOther::assignmentInAssertError(const Token *tok, const std::string &va
}
//---------------------------------------------------------------------------
// 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
// if ((x != 1) || (x != 3)) // expression always true
// if ((x == 1) && (x == 3)) // expression always false
// if ((x < 1) && (x > 3)) // expression always false
// if ((x > 3) || (x < 10)) // expression always true
// if ((x > 5) && (x != 1)) // second comparison always true
//
// Check for suspect logic for an expression consisting of 2 comparison
// expressions with a shared variable and constants and a logical operator
// between them.
//
// Suggest a different logical operator when the logical operator between
// the comparisons is probably wrong.
//
// Inform that second comparison is always true when first comparison is true.
//---------------------------------------------------------------------------
void CheckOther::checkIncorrectLogicOperator()
{
@ -764,7 +774,8 @@ void CheckOther::checkIncorrectLogicOperator()
while (tok && endTok)
{
// Find a pair of OR'd terms, with or without parenthesis
// Find a pair of comparison expressions with or without parenthesis
// with a shared variable and constants and with a logical operator between them.
// e.g. if (x != 3 || x != 4)
const Token *logicTok = NULL, *term1Tok = NULL, *term2Tok = NULL;
const Token *op1Tok = NULL, *op2Tok = NULL, *op3Tok = NULL, *nextTok = NULL;
@ -794,9 +805,11 @@ void CheckOther::checkIncorrectLogicOperator()
std::string firstConstant, secondConstant;
bool varFirst1, varFirst2;
unsigned int varId;
const Token *varTok = NULL;
if (Token::Match(term1Tok, "%var% %any% %num%"))
{
varId = term1Tok->varId();
varTok = term1Tok;
varId = varTok->varId();
if (!varId)
{
tok = Token::findmatch(endTok->next(), conditionPattern);
@ -808,7 +821,8 @@ void CheckOther::checkIncorrectLogicOperator()
}
else if (Token::Match(term1Tok, "%num% %any% %var%"))
{
varId = term1Tok->tokAt(2)->varId();
varTok = term1Tok->tokAt(2);
varId = varTok->varId();
if (!varId)
{
tok = Token::findmatch(endTok->next(), conditionPattern);
@ -867,6 +881,7 @@ void CheckOther::checkIncorrectLogicOperator()
enum Position { First, Second, NA };
enum Relation { Equal, NotEqual, Less, LessEqual, More, MoreEqual };
enum LogicError { Exclusion, AlwaysTrue, AlwaysFalse, AlwaysFalseOr };
struct Condition
{
const char *before;
@ -877,27 +892,31 @@ void CheckOther::checkIncorrectLogicOperator()
const char *op3TokStr;
const char *after;
Relation relation;
bool state;
LogicError error;
} conditions[] =
{
{ "!!&&", NA, "!=", "||", NA, "!=", "!!&&", NotEqual, true }, // (x != 1) || (x != 3) <- always true
{ "(", NA, "==", "&&", NA, "==", ")", NotEqual, false }, // (x == 1) && (x == 3) <- always false
{ "(", First, "<", "&&", First, ">", ")", LessEqual, false }, // (x < 1) && (x > 3) <- always false
{ "(", First, ">", "&&", First, "<", ")", MoreEqual, false }, // (x > 3) && (x < 1) <- always false
{ "(", Second, ">", "&&", First, ">", ")", LessEqual, false }, // (1 > x) && (x > 3) <- always false
{ "(", First, ">", "&&", Second, ">", ")", MoreEqual, false }, // (x > 3) && (1 > x) <- always false
{ "(", First, "<", "&&", Second, "<", ")", LessEqual, false }, // (x < 1) && (3 < x) <- always false
{ "(", Second, "<", "&&", First, "<", ")", MoreEqual, false }, // (3 < x) && (x < 1) <- always false
{ "(", Second, ">", "&&", Second, "<", ")", LessEqual, false }, // (1 > x) && (3 < x) <- always false
{ "(", Second, "<", "&&", Second, ">", ")", MoreEqual, false }, // (3 < x) && (1 > x) <- always false
{ "(", First , ">|>=", "||", First, "<|<=", ")", Less, true }, // (x > 3) || (x < 10) <- always true
{ "(", First , "<|<=", "||", First, ">|>=", ")", More, true }, // (x < 10) || (x > 3) <- always true
{ "(", Second, "<|<=", "||", First, "<|<=", ")", Less, true }, // (3 < x) || (x < 10) <- always true
{ "(", First, "<|<=", "||", Second, "<|<=", ")", More, true }, // (x < 10) || (3 < x) <- always true
{ "(", First, ">|>=", "||", Second, ">|>=", ")", Less, true }, // (x > 3) || (10 > x) <- always true
{ "(", Second, ">|>=", "||", First, ">|>=", ")", More, true }, // (10 > x) || (x > 3) <- always true
{ "(", Second, "<|<=", "||", Second, ">|<=", ")", Less, true }, // (3 < x) || (10 > x) <- always true
{ "(", Second, ">|>=", "||", Second, "<|<=", ")", More, true }, // (10 > x) || (3 < x) <- always true
{ "!!&&", NA, "!=", "||", NA, "!=", "!!&&", NotEqual, Exclusion }, // (x != 1) || (x != 3) <- always true
{ "(", NA, "==", "&&", NA, "==", ")", NotEqual, AlwaysFalseOr }, // (x == 1) && (x == 3) <- always false
{ "(", First, "<", "&&", First, ">", ")", LessEqual, AlwaysFalseOr }, // (x < 1) && (x > 3) <- always false
{ "(", First, ">", "&&", First, "<", ")", MoreEqual, AlwaysFalseOr }, // (x > 3) && (x < 1) <- always false
{ "(", Second, ">", "&&", First, ">", ")", LessEqual, AlwaysFalseOr }, // (1 > x) && (x > 3) <- always false
{ "(", First, ">", "&&", Second, ">", ")", MoreEqual, AlwaysFalseOr }, // (x > 3) && (1 > x) <- always false
{ "(", First, "<", "&&", Second, "<", ")", LessEqual, AlwaysFalseOr }, // (x < 1) && (3 < x) <- always false
{ "(", Second, "<", "&&", First, "<", ")", MoreEqual, AlwaysFalseOr }, // (3 < x) && (x < 1) <- always false
{ "(", Second, ">", "&&", Second, "<", ")", LessEqual, AlwaysFalseOr }, // (1 > x) && (3 < x) <- always false
{ "(", Second, "<", "&&", Second, ">", ")", MoreEqual, AlwaysFalseOr }, // (3 < x) && (1 > x) <- always false
{ "(", First , ">|>=", "||", First, "<|<=", ")", Less, Exclusion }, // (x > 3) || (x < 10) <- always true
{ "(", First , "<|<=", "||", First, ">|>=", ")", More, Exclusion }, // (x < 10) || (x > 3) <- always true
{ "(", Second, "<|<=", "||", First, "<|<=", ")", Less, Exclusion }, // (3 < x) || (x < 10) <- always true
{ "(", First, "<|<=", "||", Second, "<|<=", ")", More, Exclusion }, // (x < 10) || (3 < x) <- always true
{ "(", First, ">|>=", "||", Second, ">|>=", ")", Less, Exclusion }, // (x > 3) || (10 > x) <- always true
{ "(", Second, ">|>=", "||", First, ">|>=", ")", More, Exclusion }, // (10 > x) || (x > 3) <- always true
{ "(", Second, "<|<=", "||", Second, ">|<=", ")", Less, Exclusion }, // (3 < x) || (10 > x) <- always true
{ "(", Second, ">|>=", "||", Second, "<|<=", ")", More, Exclusion }, // (10 > x) || (3 < x) <- always true
{ "(", First, ">", "&&", NA, "!=", ")", More, AlwaysTrue }, // (x > 5) && (x != 1) <- second expression always true
{ "(", Second, "<", "&&", NA, "!=", ")", More, AlwaysTrue }, // (5 < x) && (x != 1) <- second expression always true
{ "(", First, ">", "&&", NA, "==", ")", More, AlwaysFalse }, // (x > 5) && (x == 1) <- second expression always false
{ "(", Second, "<", "&&", NA, "==", ")", More, AlwaysFalse }, // (5 < x) && (x == 1) <- second expression always false
};
for (unsigned int i = 0; i < (sizeof(conditions) / sizeof(conditions[0])); i++)
@ -929,7 +948,17 @@ void CheckOther::checkIncorrectLogicOperator()
(conditions[i].relation == LessEqual && MathLib::isLessEqual(firstConstant, secondConstant)) ||
(conditions[i].relation == More && MathLib::isGreater(firstConstant, secondConstant)) ||
(conditions[i].relation == MoreEqual && MathLib::isGreaterEqual(firstConstant, secondConstant)))
incorrectLogicOperatorError(term1Tok, conditions[i].state);
{
if (conditions[i].error == Exclusion || conditions[i].error == AlwaysFalseOr)
incorrectLogicOperatorError(term1Tok, conditions[i].error == Exclusion);
else
{
std::string text("When " + varTok->str() + " is greater than " + firstConstant + ", the comparison " +
varTok->str() + " " + conditions[i].op3TokStr + " " + secondConstant +
" is always " + (conditions[i].error == AlwaysTrue ? "true." : "false."));
secondAlwaysTrueFalseWhenFirstTrueError(term1Tok, text);
}
}
}
}
@ -948,6 +977,11 @@ void CheckOther::incorrectLogicOperatorError(const Token *tok, bool always)
"incorrectLogicOperator", "Expression always evaluates to false. Did you intend to use || instead?");
}
void CheckOther::secondAlwaysTrueFalseWhenFirstTrueError(const Token *tok, const std::string &truefalse)
{
reportError(tok, Severity::style, "secondAlwaysTrueFalseWhenFirstTrue", truefalse);
}
//---------------------------------------------------------------------------
// try {} catch (std::exception err) {} <- Should be "std::exception& err"
//---------------------------------------------------------------------------

2
lib/checkother.h
View File

@ -260,6 +260,7 @@ public:
void selfAssignmentError(const Token *tok, const std::string &varname);
void assignmentInAssertError(const Token *tok, const std::string &varname);
void incorrectLogicOperatorError(const Token *tok, bool always);
void secondAlwaysTrueFalseWhenFirstTrueError(const Token *tok, const std::string &truefalse);
void misusedScopeObjectError(const Token *tok, const std::string &varname);
void catchExceptionByValueError(const Token *tok);
void memsetZeroBytesError(const Token *tok, const std::string &varname);
@ -310,6 +311,7 @@ public:
c.assignmentInAssertError(0, "varname");
c.invalidScanfError(0);
c.incorrectLogicOperatorError(0, true);
c.secondAlwaysTrueFalseWhenFirstTrueError(0, "when first comparison is true, the 2nd comparison is always true");
c.unusedVariableError(0, "varname");
c.allocatedButUnusedVariableError(0, "varname");
c.unreadVariableError(0, "varname");

116
test/testother.cpp
View File

@ -104,6 +104,7 @@ private:
TEST_CASE(incorrectLogicOperator1);
TEST_CASE(incorrectLogicOperator2);
TEST_CASE(secondAlwaysTrueFalseWhenFirstTrueError);
TEST_CASE(catchExceptionByValue);
@ -2321,6 +2322,121 @@ private:
ASSERT_EQUALS("", errout.str());
}
void secondAlwaysTrueFalseWhenFirstTrueError()
{
check("void f(int x) {\n"
" if (x > 5 && x != 1)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (style) When x is greater than 5, the comparison x != 1 is always true.\n", errout.str());
check("void f(int x) {\n"
" if (x > 5 && x != 6)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("", errout.str());
check("void f(int x) {\n"
" if ((x > 5) && (x != 1))\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (style) When x is greater than 5, the comparison x != 1 is always true.\n", errout.str());
check("void f(int x) {\n"
" if ((x > 5) && (x != 6))\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("", errout.str());
check("void f(int x) {\n"
" if (5 < x && x != 1)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (style) When x is greater than 5, the comparison x != 1 is always true.\n", errout.str());
check("void f(int x) {\n"
" if (5 < x && x != 6)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("", errout.str());
check("void f(int x) {\n"
" if ((5 < x) && (x != 1))\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (style) When x is greater than 5, the comparison x != 1 is always true.\n", errout.str());
check("void f(int x) {\n"
" if ((5 < x) && (x != 6))\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("", errout.str());
check("void f(int x) {\n"
" if (x > 5 && x == 1)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (style) When x is greater than 5, the comparison x == 1 is always false.\n", errout.str());
check("void f(int x) {\n"
" if (x > 5 && x == 6)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("", errout.str());
check("void f(int x) {\n"
" if ((x > 5) && (x == 1))\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (style) When x is greater than 5, the comparison x == 1 is always false.\n", errout.str());
check("void f(int x) {\n"
" if ((x > 5) && (x == 6))\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("", errout.str());
check("void f(int x) {\n"
" if (5 < x && x == 1)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (style) When x is greater than 5, the comparison x == 1 is always false.\n", errout.str());
check("void f(int x) {\n"
" if (5 < x && x == 6)\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("", errout.str());
check("void f(int x) {\n"
" if ((5 < x) && (x == 1))\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("[test.cpp:2]: (style) When x is greater than 5, the comparison x == 1 is always false.\n", errout.str());
check("void f(int x) {\n"
" if ((5 < x) && (x == 6))\n"
" a++;\n"
"}\n"
);
ASSERT_EQUALS("", errout.str());
}
void catchExceptionByValue()
{
check("void f() {\n"