/****************************************
* 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;
}
continue;
}
if (sc->func->setUnsafe())
{
if (!gag)
error(ae->loc, "scope variable %s assigned to non-scope %s", v->toChars(), e1->toChars());
result = true;
}
}
else if (v->storage_class & STCvariadic && p == sc->func)
{
Type *tb = v->type->toBasetype();
if (tb->ty == Tarray || tb->ty == Tsarray)
{
if (va && !va->isDataseg() && !va->doNotInferScope)
{
if (!va->isScope() && inferScope)
{ //printf("inferring scope for %s\n", va->toChars());
va->storage_class |= STCscope | STCscopeinferred;
}
continue;
}
if (sc->func->setUnsafe())
{
if (!gag)
error(ae->loc, "variadic variable %s assigned to non-scope %s", v->toChars(), e1->toChars());
result = true;
}
}
}
else
{
/* v is not 'scope', and we didn't check the scope of where we assigned it to.
* It may escape via that assignment, therefore, v can never be 'scope'.
*/
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 va's lifetime encloses v's, then error
if (va &&
((va->enclosesLifetimeOf(v) && !(v->storage_class & STCparameter)) || va->storage_class & STCref) &&
sc->func->setUnsafe())
{
if (!gag)
error(ae->loc, "address of variable %s assigned to %s with longer lifetime", v->toChars(), va->toChars());
result = true;
continue;
}
if (!(va && va->isScope()))
v->storage_class &= ~STCmaybescope;
if ((v->storage_class & (STCref | STCout)) == 0 && p == sc->func)
{
if (va && !va->isDataseg() && !va->doNotInferScope)
{
if (!va->isScope() && inferScope)
{ //printf("inferring scope for %s\n", va->toChars());
va->storage_class |= STCscope | STCscopeinferred;
}
continue;
}
if (sc->func->setUnsafe())
{
if (!gag)
error(ae->loc, "reference to local variable %s assigned to non-scope %s", v->toChars(), e1->toChars());
result = true;
}
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();
if (!(va && va->isScope()))
v->storage_class &= ~STCmaybescope;
if ((v->storage_class & (STCref | STCout | STCscope)) && p == sc->func)
{
if (va && !va->isDataseg() && !va->doNotInferScope)
{
/* Don't infer STCscope for va, because then a closure
* won't be generated for sc->func.
*/
//if (!va->isScope() && inferScope)
//va->storage_class |= STCscope | STCscopeinferred;
continue;
}
if (sc->func->setUnsafe())
{
if (!gag)
error(ae->loc, "reference to local %s assigned to non-scope %s in @safe code", v->toChars(), e1->toChars());
result = true;
}
continue;
}
}
}
for (size_t i = 0; i < er.byexp.dim; i++)
{
Expression *ee = er.byexp[i];
if (va && !va->isDataseg() && !va->doNotInferScope)
{
if (!va->isScope() && inferScope)
{ //printf("inferring scope for %s\n", va->toChars());
va->storage_class |= STCscope | STCscopeinferred;
}
continue;
}
if (sc->func->setUnsafe())
{
if (!gag)
error(ee->loc, "reference to stack allocated value returned by %s assigned to non-scope %s",
ee->toChars(), e1->toChars());
result = true;
}
}
return result;
}
