Method string_c_str

lib/checkstl.cpp:2026–2220

}

void CheckStlImpl::string_c_str()
{
    const bool printInconclusive = mSettings.certainty.isEnabled(Certainty::inconclusive);
    const bool printPerformance = mSettings.severity.isEnabled(Severity::performance);

    const SymbolDatabase* symbolDatabase = mTokenizer->getSymbolDatabase();

    logChecker("CheckStl::string_c_str");

    // Find all functions that take std::string as argument
    struct StrArg {
        nonneg int n;
        std::string argtype;
    };
    std::multimap<const Function*, StrArg> c_strFuncParam;
    if (printPerformance) {
        for (const Scope &scope : symbolDatabase->scopeList) {
            for (const Function &func : scope.functionList) {
                nonneg int numpar = 0;
                for (const Variable &var : func.argumentList) {
                    numpar++;
                    if ((var.isStlStringType() || var.isStlStringViewType()) && (!var.isReference() || var.isConst()))
                        c_strFuncParam.emplace(&func, StrArg{ numpar, var.getTypeName() });
                }
            }
        }
    }

    auto isString = [](const Token* str) -> bool {
        while (Token::Match(str, "::|."))
            str = str->astOperand2();
        if (Token::Match(str, "(|[") && !(str->valueType() && str->valueType()->type == ValueType::ITERATOR))
            str = str->previous();
        return str && ((str->variable() && str->variable()->isStlStringType()) || // variable
                       (str->function() && isStlStringType(str->function()->retDef)) || // function returning string
                       (str->valueType() && str->valueType()->type == ValueType::ITERATOR && isStlStringType(str->valueType()->containerTypeToken))); // iterator pointing to string
    };

    // Try to detect common problems when using string::c_str()
    for (const Scope &scope : symbolDatabase->scopeList) {
        if (scope.type != ScopeType::eFunction || !scope.function)
            continue;

        enum : std::uint8_t {charPtr, stdString, stdStringConstRef, Other} returnType = Other;
        if (Token::Match(scope.function->tokenDef->tokAt(-2), "char|wchar_t *"))
            returnType = charPtr;
        else if (Token::Match(scope.function->tokenDef->tokAt(-5), "const std :: string|wstring &"))
            returnType = stdStringConstRef;
        else if (Token::Match(scope.function->tokenDef->tokAt(-3), "std :: string|wstring !!&"))
            returnType = stdString;

        for (const Token *tok = scope.bodyStart; tok && tok != scope.bodyEnd; tok = tok->next()) {
            // Invalid usage..
            if (Token::Match(tok, "throw %var% . c_str|data ( ) ;") && isLocal(tok->next()) &&
                tok->next()->variable() && tok->next()->variable()->isStlStringType()) {
                string_c_strThrowError(tok);
            } else if (tok->variable() && tok->strAt(1) == "=") {
                if (Token::Match(tok->tokAt(2), "%var% . str ( ) . c_str|data ( ) ;")) {