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Fix #11166 inefficient way to remove last character from std::string (#4267) 

* Fix #11166 inefficient way to remove last character from std::string

* Format

* Modify message, add test

* Format

* Fix another warning
This commit is contained in:
chrchr-github 2022-07-11 23:07:37 +02:00 committed by GitHub
parent c5dcd49dae
commit 47c2a01392
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9 changed files with 60 additions and 28 deletions
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43
lib/checkstl.cpp
View File

@ -2157,15 +2157,18 @@ void CheckStl::uselessCalls()
if (!var || !var->isStlType())
continue;
uselessCallsSwapError(tok, tok->str());
} else if (printPerformance && Token::Match(tok, "%var% . substr (") &&
tok->variable() && tok->variable()->isStlStringType()) {
if (Token::Match(tok->tokAt(4), "0| )")) {
uselessCallsSubstrError(tok, false);
} else if (tok->strAt(4) == "0" && tok->linkAt(3)->strAt(-1) == "npos") {
if (!tok->linkAt(3)->previous()->variable()) // Make sure that its no variable
uselessCallsSubstrError(tok, false);
} else if (Token::simpleMatch(tok->linkAt(3)->tokAt(-2), ", 0 )"))
uselessCallsSubstrError(tok, true);
} else if (printPerformance && Token::Match(tok, "%var% . substr (") && tok->variable() && tok->variable()->isStlStringType()) {
const Token* funcTok = tok->tokAt(3);
const std::vector<const Token*> args = getArguments(funcTok);
if (Token::Match(tok->tokAt(-2), "%var% =") && tok->varId() == tok->tokAt(-2)->varId() &&
!args.empty() && args[0]->hasKnownIntValue() && args[0]->getKnownIntValue() == 0) {
uselessCallsSubstrError(tok, Token::simpleMatch(funcTok->astParent(), "=") ? SubstrErrorType::PREFIX : SubstrErrorType::PREFIX_CONCAT);
} else if (args.empty() || (args[0]->hasKnownIntValue() && args[0]->getKnownIntValue() == 0 &&
(args.size() == 1 || (args.size() == 2 && tok->linkAt(3)->strAt(-1) == "npos" && !tok->linkAt(3)->previous()->variable())))) {
uselessCallsSubstrError(tok, SubstrErrorType::COPY);
} else if (args.size() == 2 && args[1]->hasKnownIntValue() && args[1]->getKnownIntValue() == 0) {
uselessCallsSubstrError(tok, SubstrErrorType::EMPTY);
}
} else if (printWarning && Token::Match(tok, "[{};] %var% . empty ( ) ;") &&
!tok->tokAt(4)->astParent() &&
tok->next()->variable() && tok->next()->variable()->isStlType(stl_containers_with_empty_and_clear))
@ -2200,12 +2203,24 @@ void CheckStl::uselessCallsSwapError(const Token *tok, const std::string &varnam
"code is inefficient. Is the object or the parameter wrong here?", CWE628, Certainty::normal);
}
void CheckStl::uselessCallsSubstrError(const Token *tok, bool empty)
void CheckStl::uselessCallsSubstrError(const Token *tok, SubstrErrorType type)
{
if (empty)
reportError(tok, Severity::performance, "uselessCallsSubstr", "Ineffective call of function 'substr' because it returns an empty string.", CWE398, Certainty::normal);
else
reportError(tok, Severity::performance, "uselessCallsSubstr", "Ineffective call of function 'substr' because it returns a copy of the object. Use operator= instead.", CWE398, Certainty::normal);
std::string msg = "Ineffective call of function 'substr' because ";
switch (type) {
case SubstrErrorType::EMPTY:
msg += "it returns an empty string.";
break;
case SubstrErrorType::COPY:
msg += "it returns a copy of the object. Use operator= instead.";
break;
case SubstrErrorType::PREFIX:
msg += "a prefix of the string is assigned to itself. Use resize() or pop_back() instead.";
break;
case SubstrErrorType::PREFIX_CONCAT:
msg += "a prefix of the string is assigned to itself. Use replace() instead.";
break;
}
reportError(tok, Severity::performance, "uselessCallsSubstr", msg, CWE398, Certainty::normal);
}
void CheckStl::uselessCallsEmptyError(const Token *tok)

5
lib/checkstl.h
View File

@ -220,7 +220,8 @@ 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, bool empty);
enum class SubstrErrorType { EMPTY, COPY, PREFIX, PREFIX_CONCAT };
void uselessCallsSubstrError(const Token* tok, SubstrErrorType type);
void uselessCallsEmptyError(const Token* tok);
void uselessCallsRemoveError(const Token* tok, const std::string& function);
@ -266,7 +267,7 @@ private:
c.redundantIfRemoveError(nullptr);
c.uselessCallsReturnValueError(nullptr, "str", "find");
c.uselessCallsSwapError(nullptr, "str");
c.uselessCallsSubstrError(nullptr, false);
c.uselessCallsSubstrError(nullptr, SubstrErrorType::COPY);
c.uselessCallsEmptyError(nullptr);
c.uselessCallsRemoveError(nullptr, "remove");
c.dereferenceInvalidIteratorError(nullptr, "i");

2
lib/checkstring.cpp
View File

@ -82,7 +82,7 @@ void CheckString::stringLiteralWriteError(const Token *tok, const Token *strValu
std::string s = strValue->str();
// 20 is an arbitrary value, the max string length shown in a warning message
if (s.size() > 20U)
s = s.substr(0,17) + "..\"";
s.replace(17, std::string::npos, "..\"");
errmsg += " " + s;
}
errmsg += " directly or indirectly is undefined behaviour.";

2
lib/cppcheck.cpp
View File

@ -316,7 +316,7 @@ static std::string executeAddon(const AddonInfo &addonInfo,
std::string message("Failed to execute addon (command: '" + pythonExe + " " + args + "'). Exitcode is nonzero.");
if (result.size() > 2) {
message = message + "\n" + message + "\nOutput:\n" + result;
message = message.substr(0,message.find_last_not_of("\n\r"));
message.resize(message.find_last_not_of("\n\r"));
}
throw InternalError(nullptr, message);
}

2
lib/errorlogger.cpp
View File

@ -843,7 +843,7 @@ std::string replaceStr(std::string s, const std::string &from, const std::string
pos1++;
continue;
}
s = s.substr(0,pos1) + to + s.substr(pos2);
s.replace(pos1, from.size(), to);
pos1 += to.size();
}
return s;

4
lib/importproject.cpp
View File

@ -139,7 +139,7 @@ static bool simplifyPathWithVariables(std::string &s, std::map<std::string, std:
variables[var] = std::string(envValue);
it1 = variables.find(var);
}
s = s.substr(0, start) + it1->second + s.substr(end + 1);
s.replace(start, end - start + 1, it1->second);
}
if (s.find("$(") != std::string::npos)
return false;
@ -644,7 +644,7 @@ static void importPropertyGroup(const tinyxml2::XMLElement *node, std::map<std::
std::string path(text);
const std::string::size_type pos = path.find("$(IncludePath)");
if (pos != std::string::npos)
path = path.substr(0,pos) + *includePath + path.substr(pos+14U);
path.replace(pos, 14U, *includePath);
*includePath = path;
}
}

3
lib/token.cpp
View File

@ -1113,7 +1113,8 @@ Token* Token::insertToken(const std::string& tokenStr, const std::string& origin
nextScopeNameAddition.append(nameTok->str());
nextScopeNameAddition.append(" ");
}
if (nextScopeNameAddition.length() > 0) nextScopeNameAddition = nextScopeNameAddition.substr(0, nextScopeNameAddition.length() - 1);
if (!nextScopeNameAddition.empty())
nextScopeNameAddition.pop_back();
}
}

12
lib/tokenize.cpp
View File

@ -2190,7 +2190,7 @@ namespace {
while (!newScope1.empty()) {
std::string::size_type separator = newScope1.rfind(" :: ", index - 1);
if (separator != std::string::npos)
newScope1 = newScope1.substr(0, separator);
newScope1.resize(separator);
else
newScope1.clear();
@ -3352,8 +3352,8 @@ void Tokenizer::calculateScopes()
usingNamespaceName += namespaceNameToken->str();
usingNamespaceName += " ";
}
if (usingNamespaceName.length() > 0)
usingNamespaceName = usingNamespaceName.substr(0, usingNamespaceName.length() - 1);
if (!usingNamespaceName.empty())
usingNamespaceName.pop_back();
tok->scopeInfo()->usingNamespaces.insert(usingNamespaceName);
} else if (Token::Match(tok, "namespace|class|struct|union %name% {|::|:|<")) {
for (Token* nameTok = tok->next(); nameTok && !Token::Match(nameTok, "{|:"); nameTok = nameTok->next()) {
@ -3364,8 +3364,8 @@ void Tokenizer::calculateScopes()
nextScopeNameAddition.append(nameTok->str());
nextScopeNameAddition.append(" ");
}
if (nextScopeNameAddition.length() > 0)
nextScopeNameAddition = nextScopeNameAddition.substr(0, nextScopeNameAddition.length() - 1);
if (!nextScopeNameAddition.empty())
nextScopeNameAddition.pop_back();
}
if (Token::simpleMatch(tok, "{")) {
@ -8106,7 +8106,7 @@ std::string Tokenizer::simplifyString(const std::string &source)
sz++;
std::istringstream istr(str.substr(i+1, sz-1));
istr >> std::oct >> c;
str = str.substr(0,i) + (char)c + str.substr(i+sz);
str = str.replace(i, sz, std::string(1U, (char)c));
continue;
}

15
test/teststl.cpp
View File

@ -4168,6 +4168,21 @@ private:
" for (;s.empty();) {}\n"
"}");
ASSERT_EQUALS("", errout.str());
// #11166
check("std::string f(std::string s) {\n"
" s = s.substr(0, s.size() - 1);\n"
" return s;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (performance) Ineffective call of function 'substr' because a prefix of the string is assigned to itself. Use resize() or pop_back() instead.\n",
errout.str());
check("std::string f(std::string s, std::size_t start, std::size_t end, const std::string& i) {\n"
" s = s.substr(0, start) + i + s.substr(end + 1);\n"
" return s;\n"
"}\n");
ASSERT_EQUALS("[test.cpp:2]: (performance) Ineffective call of function 'substr' because a prefix of the string is assigned to itself. Use replace() instead.\n",
errout.str());
}
void stabilityOfChecks() {