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Fixed #2722 (new check: statement that is always true (strcmp))

This commit is contained in:
Zachary Blair 2011-04-25 22:45:27 -07:00
parent c6f71321bd
commit 46645ab327
3 changed files with 108 additions and 1 deletions
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52
lib/checkother.cpp
View File

@ -3296,6 +3296,58 @@ void CheckOther::duplicateExpressionError(const Token *tok1, const Token *tok2,
"determine if it is correct.");
}
//---------------------------------------------------------------------------
// Check for string comparison involving two static strings.
// if(strcmp("00FF00","00FF00")==0) // <- statement is always true
//---------------------------------------------------------------------------
void CheckOther::checkAlwaysTrueOrFalseStringCompare()
{
if (!_settings->_checkCodingStyle)
return;
const char pattern1[] = "strcmp|stricmp|strcmpi|strcasecmp|wcscmp ( %str% , %str% )";
const char pattern2[] = "QString :: compare ( %str% , %str% )";
const Token *tok = _tokenizer->tokens();
while (tok && (tok = Token::findmatch(tok, pattern1)) != NULL)
{
alwaysTrueFalseStringCompare(tok, tok->strAt(2), tok->strAt(4));
tok = tok->tokAt(5);
}
tok = _tokenizer->tokens();
while (tok && (tok = Token::findmatch(tok, pattern2)) != NULL)
{
alwaysTrueFalseStringCompare(tok, tok->strAt(4), tok->strAt(6));
tok = tok->tokAt(7);
}
}
void CheckOther::alwaysTrueFalseStringCompare(const Token *tok, const std::string& str1, const std::string& str2)
{
const size_t stringLen = 10;
const std::string string1 = (str1.size() < stringLen) ? str1 : (str1.substr(0, stringLen-2) + "..");
const std::string string2 = (str2.size() < stringLen) ? str2 : (str2.substr(0, stringLen-2) + "..");
if (str1 == str2)
{
reportError(tok, Severity::warning, "staticStringCompare",
"Comparison of always identical static strings.\n"
"The compared strings, '" + string1 + "' and '" + string2 + "', are always identical. "
"If the purpose is to compare these two strings, the comparison is unnecessary. "
"If the strings are supposed to be different, then there is a bug somewhere.");
}
else
{
reportError(tok, Severity::performance, "staticStringCompare",
"Unnecessary comparison of static strings.\n"
"The compared strings, '" + string1 + "' and '" + string2 + "', are static and always different. "
"If the purpose is to compare these two strings, the comparison is unnecessary.");
}
}
//-----------------------------------------------------------------------------
void CheckOther::cstyleCastError(const Token *tok)

9
lib/checkother.h
View File

@ -98,6 +98,7 @@ public:
checkOther.checkIncrementBoolean();
checkOther.checkComparisonOfBoolWithInt();
checkOther.checkSwitchCaseFallThrough();
checkOther.checkAlwaysTrueOrFalseStringCompare();
}
/** @brief Clarify calculation for ".. a * b ? .." */
@ -216,6 +217,9 @@ public:
/** @brief %Check for suspicious code with the same expression on both sides of operator (e.g "if (a && a)") */
void checkDuplicateExpression();
/** @brief %Check for suspicious code that compares string literals for equality */
void checkAlwaysTrueOrFalseStringCompare();
// Error messages..
void cstyleCastError(const Token *tok);
void dangerousUsageStrtolError(const Token *tok);
@ -247,6 +251,7 @@ public:
void duplicateIfError(const Token *tok1, const Token *tok2);
void duplicateBranchError(const Token *tok1, const Token *tok2);
void duplicateExpressionError(const Token *tok1, const Token *tok2, const std::string &op);
void alwaysTrueFalseStringCompare(const Token *tok, const std::string& str1, const std::string& str2);
void getErrorMessages(ErrorLogger *errorLogger, const Settings *settings)
{
@ -294,6 +299,7 @@ public:
c.duplicateIfError(0, 0);
c.duplicateBranchError(0, 0);
c.duplicateExpressionError(0, 0, "&&");
c.alwaysTrueFalseStringCompare(0, "str1", "str2");
}
std::string myName() const
@ -336,7 +342,8 @@ public:
"* Clarify calculation with parentheses\n"
"* using increment on boolean\n"
"* comparison of a boolean with a non-zero integer\n"
"* suspicious condition (assignment+comparison)"
"* suspicious condition (assignment+comparison)\n"
"* suspicious condition (runtime comparison of string literals)\n"
// optimisations
"* optimisation: detect post increment/decrement\n";

48
test/testother.cpp
View File

@ -117,6 +117,8 @@ private:
TEST_CASE(duplicateBranch);
TEST_CASE(duplicateExpression1);
TEST_CASE(duplicateExpression2); // ticket #2730
TEST_CASE(alwaysTrueFalseStringCompare);
}
void check(const char code[], const char *filename = NULL)
@ -216,6 +218,7 @@ private:
// Check..
CheckOther checkOther(&tokenizer, &settings, &logger);
checkOther.checkSwitchCaseFallThrough();
checkOther.checkAlwaysTrueOrFalseStringCompare();
logger.reportUnmatchedSuppressions(settings.nomsg.getUnmatchedLocalSuppressions(filename));
}
@ -2549,6 +2552,51 @@ private:
"[test.cpp:8]: (error) Passing value -1.0 to sqrt() leads to undefined result\n"
"[test.cpp:9]: (error) Passing value -1.0 to sqrtf() leads to undefined result\n", errout.str());
}
void alwaysTrueFalseStringCompare()
{
check_preprocess_suppress(
"#define MACRO \"00FF00\"\n"
"int main()\n"
"{\n"
" if (strcmp(MACRO,\"00FF00\") == 0)"
" {"
" std::cout << \"Equal\n\""
" }"
"}");
ASSERT_EQUALS("[test.cpp:4]: (warning) Comparison of always identical static strings.\n", errout.str());
check_preprocess_suppress(
"int main()\n"
"{\n"
" if (stricmp(\"hotdog\",\"HOTdog\") == 0)"
" {"
" std::cout << \"Equal\n\""
" }"
"}");
ASSERT_EQUALS("[test.cpp:3]: (performance) Unnecessary comparison of static strings.\n", errout.str());
check_preprocess_suppress(
"#define MACRO \"Hotdog\"\n"
"int main()\n"
"{\n"
" if (QString::compare(\"Hamburger\", MACRO) == 0)"
" {"
" std::cout << \"Equal\n\""
" }"
"}");
ASSERT_EQUALS("[test.cpp:4]: (performance) Unnecessary comparison of static strings.\n", errout.str());
check_preprocess_suppress(
"int main()\n"
"{\n"
" if (QString::compare(argv[2], \"hotdog\") == 0)"
" {"
" std::cout << \"Equal\n\""
" }"
"}");
ASSERT_EQUALS("", errout.str());
}
};
REGISTER_TEST(TestOther)