C++ VarDeclaration::toParent2方法代码示例

        void visit(IndexExp *e)
        {
            if (e->e1->op == TOKvar)
            {
                VarDeclaration *v = ((VarExp *)e->e1)->var->isVarDeclaration();
                if (v && v->toParent2() == sc->func)
                {
                    Type *tb = v->type->toBasetype();
                    if (tb->ty == Tarray || tb->ty == Tsarray)
                    {
                        if (v->storage_class & STCvariadic)
                        {
                            error(e->loc, "escaping reference to the payload of variadic parameter %s", v);
                            return;
                        }
                    }
                }
            }

            Type *tb = e->e1->type->toBasetype();
            if (tb->ty == Tsarray)
            {
                e->e1->accept(this);
            }
        }

        void check(Loc loc, Declaration *d)
        {
            assert(d);
            VarDeclaration *v = d->isVarDeclaration();
            if (v && v->toParent2() == sc->func)
            {
                if (v->isDataseg())
                    return;
                if ((v->storage_class & (STCref | STCout)) == 0)
                {
                    error(loc, "escaping reference to local variable %s", v);
                    return;
                }

                if (global.params.useDIP25 &&
                        (v->storage_class & (STCref | STCout)) && !(v->storage_class & (STCreturn | STCforeach)))
                {
                    if (sc->func->flags & FUNCFLAGreturnInprocess)
                    {
                        //printf("inferring 'return' for variable '%s'\n", v->toChars());
                        v->storage_class |= STCreturn;
                        if (v == sc->func->vthis)
                        {
                            TypeFunction *tf = (TypeFunction *)sc->func->type;
                            if (tf->ty == Tfunction)
                            {
                                //printf("'this' too\n");
                                tf->isreturn = true;
                            }
                        }
                    }
                    else if (sc->module && sc->module->isRoot())
                    {
                        //printf("escaping reference to local ref variable %s\n", v->toChars());
                        //printf("storage class = x%llx\n", v->storage_class);
                        error(loc, "escaping reference to local ref variable %s", v);
                    }
                    return;
                }

                if (v->storage_class & STCref &&
                        v->storage_class & (STCforeach | STCtemp) &&
                        v->init)
                {
                    // (ref v = ex; ex)
                    if (ExpInitializer *ez = v->init->isExpInitializer())
                    {
                        assert(ez->exp && ez->exp->op == TOKconstruct);
                        Expression *ex = ((ConstructExp *)ez->exp)->e2;
                        ex->accept(this);
                        return;
                    }
                }
            }
        }

/****************************************
 * Function parameter par is being initialized to arg,
 * and par may escape.
 * Detect if scoped values can escape this way.
 * Print error messages when these are detected.
 * Params:
 *      sc = used to determine current function and module
 *      par = identifier of function parameter
 *      arg = initializer for param
 *      gag = do not print error messages
 * Returns:
 *      true if pointers to the stack can escape via assignment
 */
bool checkParamArgumentEscape(Scope *sc, FuncDeclaration *fdc, Identifier *par, Expression *arg, bool gag)
{
    //printf("checkParamArgumentEscape(arg: %s par: %s)\n", arg->toChars(), par->toChars());
    //printf("type = %s, %d\n", arg->type->toChars(), arg->type->hasPointers());

    if (!arg->type->hasPointers())
        return false;

    EscapeByResults er;

    escapeByValue(arg, &er);

    if (!er.byref.dim && !er.byvalue.dim && !er.byfunc.dim && !er.byexp.dim)
        return false;

    bool result = false;

    for (size_t i = 0; i < er.byvalue.dim; i++)
    {
        //printf("byvalue %s\n", v->toChars());
        VarDeclaration *v = er.byvalue[i];
        if (v->isDataseg())
            continue;

        Dsymbol *p = v->toParent2();

        v->storage_class &= ~STCmaybescope;

        if (v->isScope())
        {
            unsafeAssign(sc, fdc, par, arg, gag, result, v, "scope variable");
        }
        else if (v->storage_class & STCvariadic && p == sc->func)
        {
            Type *tb = v->type->toBasetype();
            if (tb->ty == Tarray || tb->ty == Tsarray)
            {
                unsafeAssign(sc, fdc, par, arg, gag, result, v, "variadic variable");
            }
        }
        else
        {
            /* v is not 'scope', and is assigned to a parameter that may escape.
             * Therefore, v can never be 'scope'.
             */
            v->doNotInferScope = true;
        }
    }

    for (size_t i = 0; i < er.byref.dim; i++)
    {
        VarDeclaration *v = er.byref[i];
        if (v->isDataseg())
            continue;

        Dsymbol *p = v->toParent2();

        v->storage_class &= ~STCmaybescope;

        if ((v->storage_class & (STCref | STCout)) == 0 && p == sc->func)
        {
            unsafeAssign(sc, fdc, par, arg, gag, result, v, "reference to local variable");
            continue;
        }
    }

    for (size_t i = 0; i < er.byfunc.dim; i++)
    {
        FuncDeclaration *fd = er.byfunc[i];
        //printf("fd = %s, %d\n", fd->toChars(), fd->tookAddressOf);
        VarDeclarations vars;
        findAllOuterAccessedVariables(fd, &vars);

        for (size_t j = 0; j < vars.dim; j++)
        {
            VarDeclaration *v = vars[j];
            //printf("v = %s\n", v->toChars());
            assert(!v->isDataseg());     // these are not put in the closureVars[]

            Dsymbol *p = v->toParent2();

            v->storage_class &= ~STCmaybescope;

            if ((v->storage_class & (STCref | STCout | STCscope)) && p == sc->func)
            {
                unsafeAssign(sc, fdc, par, arg, gag, result, v, "reference to local");
                continue;
//.........这里部分代码省略.........

static bool checkReturnEscapeImpl(Scope *sc, Expression *e, bool refs, bool gag)
{
    //printf("[%s] checkReturnEscapeImpl, e = %s\n", e->loc->toChars(), e->toChars());
    EscapeByResults er;

    if (refs)
        escapeByRef(e, &er);
    else
        escapeByValue(e, &er);

    if (!er.byref.dim && !er.byvalue.dim && !er.byexp.dim)
        return false;

    bool result = false;
    for (size_t i = 0; i < er.byvalue.dim; i++)
    {
        VarDeclaration *v = er.byvalue[i];
        //printf("byvalue %s\n", v->toChars());
        if (v->isDataseg())
            continue;

        Dsymbol *p = v->toParent2();

        if ((v->isScope() || (v->storage_class & STCmaybescope)) &&
            !(v->storage_class & STCreturn) &&
            v->isParameter() &&
            sc->func->flags & FUNCFLAGreturnInprocess &&
            p == sc->func)
        {
            inferReturn(sc->func, v);        // infer addition of 'return'
            continue;
        }

        if (v->isScope())
        {
            if (v->storage_class & STCreturn)
                continue;

            if (sc->_module && sc->_module->isRoot() &&
                /* This case comes up when the ReturnStatement of a __foreachbody is
                 * checked for escapes by the caller of __foreachbody. Skip it.
                 *
                 * struct S { static int opApply(int delegate(S*) dg); }
                 * S* foo() {
                 *    foreach (S* s; S) // create __foreachbody for body of foreach
                 *        return s;     // s is inferred as 'scope' but incorrectly tested in foo()
                 *    return null; }
                 */
                !(!refs && p->parent == sc->func))
            {
                // Only look for errors if in module listed on command line
                if (global.params.vsafe) // https://issues.dlang.org/show_bug.cgi?id=17029
                {
                    if (!gag)
                        error(e->loc, "scope variable %s may not be returned", v->toChars());
                    result = true;
                }
                continue;
            }
        }
        else if (v->storage_class & STCvariadic && p == sc->func)
        {
            Type *tb = v->type->toBasetype();
            if (tb->ty == Tarray || tb->ty == Tsarray)
            {
                if (!gag)
                    error(e->loc, "returning `%s` escapes a reference to variadic parameter `%s`", e->toChars(), v->toChars());
                result = false;
            }
        }
        else
        {
            //printf("no infer for %s\n", v->toChars());
            v->doNotInferScope = true;
        }
    }

    for (size_t i = 0; i < er.byref.dim; i++)
    {
        VarDeclaration *v = er.byref[i];
        //printf("byref %s\n", v->toChars());
        if (v->isDataseg())
            continue;

        Dsymbol *p = v->toParent2();

        if ((v->storage_class & (STCref | STCout)) == 0)
        {
            if (p == sc->func)
            {
                escapingRef(v, e, result, gag);
                continue;
            }
            FuncDeclaration *fd = p->isFuncDeclaration();
            if (fd && sc->func->flags & FUNCFLAGreturnInprocess)
            {
                /* Code like:
                 *   int x;
                 *   auto dg = () { return &x; }
                 * Making it:
//.........这里部分代码省略.........

/****************************************
 * Given an AssignExp, determine if the lvalue will cause
 * the contents of the rvalue to escape.
 * Print error messages when these are detected.
 * Infer 'scope' for the lvalue where possible, in order
 * to eliminate the error.
 * Params:
 *      sc = used to determine current function and module
 *      ae = AssignExp to check for any pointers to the stack
 *      gag = do not print error messages
 * Returns:
 *      true if pointers to the stack can escape via assignment
 */
bool checkAssignEscape(Scope *sc, Expression *e, bool gag)
{
    //printf("checkAssignEscape(e: %s)\n", e->toChars());
    if (e->op != TOKassign && e->op != TOKblit && e->op != TOKconstruct)
        return false;
    AssignExp *ae = (AssignExp *)e;
    Expression *e1 = ae->e1;
    Expression *e2 = ae->e2;
    //printf("type = %s, %d\n", e1->type->toChars(), e1->type->hasPointers());

    if (!e1->type->hasPointers())
        return false;

    if (e1->op == TOKslice)
        return false;

    EscapeByResults er;

    escapeByValue(e2, &er);

    if (!er.byref.dim && !er.byvalue.dim && !er.byfunc.dim && !er.byexp.dim)
        return false;

    VarDeclaration *va = NULL;
    while (e1->op == TOKdotvar)
        e1 = ((DotVarExp *)e1)->e1;

    if (e1->op == TOKvar)
        va = ((VarExp *)e1)->var->isVarDeclaration();
    else if (e1->op == TOKthis)
        va = ((ThisExp *)e1)->var->isVarDeclaration();
    else if (e1->op == TOKindex)
    {
        IndexExp *ie = (IndexExp *)e1;
        if (ie->e1->op == TOKvar && ie->e1->type->toBasetype()->ty == Tsarray)
            va = ((VarExp *)ie->e1)->var->isVarDeclaration();
    }

    // Try to infer 'scope' for va if in a function not marked @system
    bool inferScope = false;
    if (va && sc->func && sc->func->type && sc->func->type->ty == Tfunction)
        inferScope = ((TypeFunction *)sc->func->type)->trust != TRUSTsystem;

    bool result = false;
    for (size_t i = 0; i < er.byvalue.dim; i++)
    {
        VarDeclaration *v = er.byvalue[i];
        //printf("byvalue: %s\n", v->toChars());
        if (v->isDataseg())
            continue;

        Dsymbol *p = v->toParent2();

        if (!(va && va->isScope()))
            v->storage_class &= ~STCmaybescope;

        if (v->isScope())
        {
            if (va && va->isScope() && va->storage_class & STCreturn && !(v->storage_class & STCreturn) &&
                sc->func->setUnsafe())
            {
                if (!gag)
                    error(ae->loc, "scope variable %s assigned to return scope %s", v->toChars(), va->toChars());
                result = true;
                continue;
            }

            // If va's lifetime encloses v's, then error
            if (va &&
                ((va->enclosesLifetimeOf(v) && !(v->storage_class & STCparameter)) ||
                 // va is class reference
                 (ae->e1->op == TOKdotvar && va->type->toBasetype()->ty == Tclass && (va->enclosesLifetimeOf(v) || !va->isScope())) ||
                 va->storage_class & STCref) &&
                sc->func->setUnsafe())
            {
                if (!gag)
                    error(ae->loc, "scope variable %s assigned to %s with longer lifetime", v->toChars(), va->toChars());
                result = true;
                continue;
            }

            if (va && !va->isDataseg() && !va->doNotInferScope)
            {
                if (!va->isScope() && inferScope)
                {   //printf("inferring scope for %s\n", va->toChars());
                    va->storage_class |= STCscope | STCscopeinferred;
                    va->storage_class |= v->storage_class & STCreturn;
//.........这里部分代码省略.........