Function checkFunctionReturnsRef

lib/checkother.cpp:3338–3365

--------------------------------------------------------------------------- This check rule works for checking the "const A a = getA()" usage when getA() returns "const A &" or "A &". In most scenarios, "const A & a = getA()" will be more efficient. ---------------------------------------------------------------------------

// In most scenarios, "const A & a = getA()" will be more efficient.
//---------------------------------------------------------------------------
static bool checkFunctionReturnsRef(const Token* tok, const Settings& settings)
{
    if (!Token::Match(tok->previous(), "%name% ("))
        return false;
    if (!Token::Match(tok->link(), ") )|}| ;")) // bailout for usage like "const A a = getA()+3"
        return false;
    const Token* dot = tok->astOperand1();
    if (Token::simpleMatch(dot, ".")) {
        const Token* varTok = dot->astOperand1();
        const int indirect = varTok->valueType() ? varTok->valueType()->pointer : 0;
        if (isVariableChanged(tok, tok->scope()->bodyEnd, indirect, varTok->varId(), /*globalvar*/ true, settings))
            return false;
        if (isTemporary(dot, &settings.library, /*unknown*/ true))
            return false;
    }
    if (exprDependsOnThis(tok->previous()))
        return false;
    const Function* func = tok->previous()->function();
    if (func && func->tokenDef->strAt(-1) == "&") {
        const Scope* fScope = func->functionScope;
        if (fScope && fScope->bodyEnd && Token::Match(fScope->bodyEnd->tokAt(-3), "return %var% ;")) {
            const Token* varTok = fScope->bodyEnd->tokAt(-2);
            if (isLargeObject(varTok->variable(), settings))
                return true;
        }
    }
    return false;
}

static bool checkVariableAssignment(const Token* tok, const ValueType* vtLhs, const Settings& settings)
{