Method checkMathFunctions

lib/checkfunctions.cpp:442–501

--------------------------------------------------------------------------- Detect passing wrong values to functions like atan(0, x); ---------------------------------------------------------------------------

// Detect passing wrong values to <cmath> functions like atan(0, x);
//---------------------------------------------------------------------------
void CheckFunctionsImpl::checkMathFunctions()
{
    const bool styleC99 = mSettings.severity.isEnabled(Severity::style) && ((mTokenizer->isC() && mSettings.standards.c != Standards::C89) || (mTokenizer->isCPP() && mSettings.standards.cpp != Standards::CPP03));
    const bool printWarnings = mSettings.severity.isEnabled(Severity::warning);

    if (!styleC99 && !printWarnings && !mSettings.isPremiumEnabled("wrongmathcall"))
        return;

    logChecker("CheckFunctions::checkMathFunctions"); // style,warning,c99,c++11

    const SymbolDatabase *symbolDatabase = mTokenizer->getSymbolDatabase();
    for (const Scope *scope : symbolDatabase->functionScopes) {
        for (const Token* tok = scope->bodyStart->next(); tok != scope->bodyEnd; tok = tok->next()) {
            if (tok->varId())
                continue;
            if (printWarnings && Token::Match(tok, "%name% ( !!)")) {
                if (tok->strAt(-1) != "."
                    && Token::Match(tok, "log|logf|logl|log10|log10f|log10l|log2|log2f|log2l ( %num% )")) {
                    const std::string& number = tok->strAt(2);
                    if ((MathLib::isInt(number) && MathLib::toBigNumber(number) <= 0) ||
                        (MathLib::isFloat(number) && MathLib::toDoubleNumber(number) <= 0.))
                        mathfunctionCallWarning(tok);
                } else if (Token::Match(tok, "log1p|log1pf|log1pl ( %num% )")) {
                    const std::string& number = tok->strAt(2);
                    if ((MathLib::isInt(number) && MathLib::toBigNumber(number) <= -1) ||
                        (MathLib::isFloat(number) && MathLib::toDoubleNumber(number) <= -1.))
                        mathfunctionCallWarning(tok);
                }
                // atan2 ( x , y): x and y can not be zero, because this is mathematically not defined
                else if (Token::Match(tok, "atan2|atan2f|atan2l ( %num% , %num% )")) {
                    if (MathLib::isNullValue(tok->strAt(2)) && MathLib::isNullValue(tok->strAt(4)))
                        mathfunctionCallWarning(tok, 2);
                }
                // fmod ( x , y) If y is zero, then either a range error will occur or the function will return zero (implementation-defined).
                else if (Token::Match(tok, "fmod|fmodf|fmodl (")) {
                    const Token* nextArg = tok->tokAt(2)->nextArgument();
                    if (nextArg && MathLib::isNullValue(nextArg->str()))
                        mathfunctionCallWarning(tok, 2);
                }
                // pow ( x , y) If x is zero, and y is negative --> division by zero
                else if (Token::Match(tok, "pow|powf|powl ( %num% , %num% )")) {
                    if (MathLib::isNullValue(tok->strAt(2)) && MathLib::isNegative(tok->strAt(4)))
                        mathfunctionCallWarning(tok, 2);
                }
            }

            if (styleC99) {
                if (Token::Match(tok, "%num% - erf (") && Tokenizer::isOneNumber(tok->str()) && tok->next()->astOperand2() == tok->tokAt(3)) {
                    mathfunctionCallWarning(tok, "1 - erf(x)", "erfc(x)");
                } else if (Token::simpleMatch(tok, "exp (") && Token::Match(tok->linkAt(1), ") - %num%") && Tokenizer::isOneNumber(tok->linkAt(1)->strAt(2)) && tok->linkAt(1)->next()->astOperand1() == tok->next()) {
                    mathfunctionCallWarning(tok, "exp(x) - 1", "expm1(x)");
                } else if (Token::simpleMatch(tok, "log (") && tok->next()->astOperand2()) {
                    const Token* plus = tok->next()->astOperand2();
                    if (plus->str() == "+" && ((plus->astOperand1() && Tokenizer::isOneNumber(plus->astOperand1()->str())) || (plus->astOperand2() && Tokenizer::isOneNumber(plus->astOperand2()->str()))))
                        mathfunctionCallWarning(tok, "log(1 + x)", "log1p(x)");
                }
            }
        }