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Improved checks in CheckStl: 

- Improved message of stlIfStrFind according to discussion on github (77d9ed1877)
- Generalized pattern for substr in CheckStl::uselessCalls; added check for substr calls like ".substr(%any%,0)" which result in an empty string.
This commit is contained in:
PKEuS 2012-04-04 19:40:28 +02:00
parent b90d9c8a19
commit bef2caf489
3 changed files with 32 additions and 35 deletions
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45
lib/checkstl.cpp
View File

@ -832,12 +832,12 @@ void CheckStl::if_find()
void CheckStl::if_findError(const Token *tok, bool str)
{
if (str)
reportError(tok, Severity::warning, "stlIfStrFind",
"Suspicious checking of string::find() return value.\n"
"Checking of string::find() return value looks Suspicious. "
"string::find will return 0 if the string is found at position 0. "
"If that is wanted to check then string::compare is a faster alternative "
"because it doesn't scan through the string.");
reportError(tok, Severity::performance, "stlIfStrFind",
"Inefficient usage of string::find in condition; string::compare would be faster.\n"
"Either inefficent or wrong usage of string::find. string::compare will be faster if "
"string::find's result is compared with 0, because it will not scan the whole "
"string. If your intention is to check that there are no findings in the string, "
"you should compare with string::npos.");
else
reportError(tok, Severity::warning, "stlIfFind", "Suspicious condition. The result of find is an iterator, but it is not properly checked.");
}
@ -1317,24 +1317,19 @@ void CheckStl::autoPointerArrayError(const Token *tok)
void CheckStl::uselessCalls()
{
for (const Token *tok = _tokenizer->tokens(); tok; tok = tok->next()) {
if (tok->varId() == 0)
continue;
/*if (Token::Match(tok, "%var% . compare (") &&
tok->varId() == tok->linkAt(3)->previous()->varId()) {
uselessCallsReturnValueError(tok, tok->tokAt(2));
} else */
if (Token::Match(tok, "%var% . compare|find|rfind|find_first_not_of|find_first_of|find_last_not_of|find_last_of ( %var% [,)]") &&
if (tok->varId() && Token::Match(tok, "%var% . compare|find|rfind|find_first_not_of|find_first_of|find_last_not_of|find_last_of ( %var% [,)]") &&
tok->varId() == tok->tokAt(4)->varId()) {
uselessCallsReturnValueError(tok->tokAt(4), tok->str(), tok->strAt(2));
} else if (Token::Match(tok, "%var% . swap ( %var% )") &&
} else if (tok->varId() && Token::Match(tok, "%var% . swap ( %var% )") &&
tok->varId() == tok->tokAt(4)->varId()) {
uselessCallsSwapError(tok, tok->str());
} else if (Token::Match(tok, "%var% . substr ( )")) {
uselessCallsSubstrError(tok, tok->str());
} else if (Token::Match(tok, "%var% . substr ( 0")) {
if (tok->strAt(5) == ")" ||
tok->linkAt(3)->strAt(-1) == "npos")
uselessCallsSubstrError(tok, tok->str());
} else if (Token::Match(tok, ". substr (")) {
if (Token::Match(tok->tokAt(3), "0| )"))
uselessCallsSubstrError(tok, false);
else if (tok->strAt(3) == "0" && tok->linkAt(2)->strAt(-1) == "npos")
uselessCallsSubstrError(tok, false);
else if (Token::Match(tok->linkAt(2)->tokAt(-2), ", 0 )"))
uselessCallsSubstrError(tok, true);
}
}
}
@ -1361,10 +1356,10 @@ void CheckStl::uselessCallsSwapError(const Token *tok, const std::string &varnam
reportError(tok, Severity::performance, "uselessCallsSwap", errmsg.str());
}
void CheckStl::uselessCallsSubstrError(const Token *tok, const std::string &varname)
void CheckStl::uselessCallsSubstrError(const Token *tok, bool empty)
{
std::ostringstream errmsg;
errmsg << "Function \'substr\' useless call. Function create copy of the \'" << varname << "\' object.\n" <<
"Function \'substr\' useless call. \'substr\' function create copy of the whole \'" << varname << "\' object which can decrease in performance. Please use \'=\' operator instead.";
reportError(tok, Severity::performance, "uselessCallsSubstr", errmsg.str());
if (empty)
reportError(tok, Severity::performance, "uselessCallsSubstr", "Useless call of function 'substr' because it returns an empty string.");
else
reportError(tok, Severity::performance, "uselessCallsSubstr", "Useless call of function 'substr' because it returns a copy of the object. Use operator= instead.");
}

4
lib/checkstl.h
View File

@ -173,7 +173,7 @@ private:
void uselessCallsReturnValueError(const Token *tok, const std::string &varname, const std::string &function);
void uselessCallsSwapError(const Token *tok, const std::string &varname);
void uselessCallsSubstrError(const Token *tok, const std::string &varname);
void uselessCallsSubstrError(const Token *tok, bool empty);
void getErrorMessages(ErrorLogger *errorLogger, const Settings *settings) const {
CheckStl c(0, settings, errorLogger);
@ -198,7 +198,7 @@ private:
c.autoPointerArrayError(0);
c.uselessCallsReturnValueError(0, "str", "find");
c.uselessCallsSwapError(0, "str");
c.uselessCallsSubstrError(0, "str");
c.uselessCallsSubstrError(0, false);
}
std::string myName() const {

18
test/teststl.cpp
View File

@ -1224,28 +1224,28 @@ private:
"{\n"
" if (s.find(\"abc\")) { }\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (warning) Suspicious checking of string::find() return value.\n", errout.str());
ASSERT_EQUALS("[test.cpp:3]: (performance) Inefficient usage of string::find in condition; string::compare would be faster.\n", errout.str());
// error (pointer)
check("void f(const std::string *s)\n"
"{\n"
" if (*s.find(\"abc\")) { }\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (warning) Suspicious checking of string::find() return value.\n", errout.str());
ASSERT_EQUALS("[test.cpp:3]: (performance) Inefficient usage of string::find in condition; string::compare would be faster.\n", errout.str());
// error (vector)
check("void f(const std::vector<std::string> &s)\n"
"{\n"
" if (s[0].find(\"abc\")) { }\n"
"}\n");
ASSERT_EQUALS("[test.cpp:3]: (warning) Suspicious checking of string::find() return value.\n", errout.str());
ASSERT_EQUALS("[test.cpp:3]: (performance) Inefficient usage of string::find in condition; string::compare would be faster.\n", errout.str());
// #3162
check("void f(const std::string& s1, const std::string& s2)\n"
"{\n"
" if ((!s1.empty()) && (0 == s1.find(s2))) { }\n"
"}");
ASSERT_EQUALS("[test.cpp:3]: (warning) Suspicious checking of string::find() return value.\n", errout.str());
ASSERT_EQUALS("[test.cpp:3]: (performance) Inefficient usage of string::find in condition; string::compare would be faster.\n", errout.str());
}
@ -1783,12 +1783,14 @@ private:
" s2 = s1.substr(x);\n"
" s1 = s2.substr(0, x);\n"
" s1 = s2.substr(0,std::string::npos);\n"
" s1 = s2.substr(x+5-n, 0);\n"
" \n"
"};\n");
ASSERT_EQUALS("[test.cpp:5]: (performance) Function \'substr\' useless call. Function create copy "
"of the \'s1\' object.\n"
"[test.cpp:8]: (performance) Function \'substr\' useless call. Function create copy "
"of the \'s2\' object.\n",errout.str());
ASSERT_EQUALS("[test.cpp:5]: (performance) Useless call of function \'substr\' because it returns a copy of "
"the object. Use operator= instead.\n"
"[test.cpp:8]: (performance) Useless call of function \'substr\' because it returns a copy of "
"the object. Use operator= instead.\n"
"[test.cpp:9]: (performance) Useless call of function \'substr\' because it returns an empty string.\n", errout.str());
check("#include <string>\n"
"int main()\n"