1115175 - Disallow functions that accept raw pointers to refcounted objects from assigning those pointers to non-local lvalues

Status: NEW

(Developer Infrastructure :: Source Code Analysis, defect)

Description

[(no longer active)]

The idea is to disallow things such as:

nsIFoo* gFoo;
void MyClass::foo(nsIFoo* aFoo, RandomClass& obj) {
  gFoo = aFoo; // assign to global, generate compiler error
  obj.mFoo = aFoo; // assign to object with unknown life time, generate compiler error
  mFoo = aFoo; // assign to member, generate compiler error
}

The first is pretty easy.  The second is also relatively easy.  The third would be tough since there are a ton of places where we do that...

Comment 1

[Aryeh Gregor (:ayg) (no longer with Mozilla)]

What's the problem here?  If the variable you're assigning to is an nsRefPtr, it's safe.  If it's a raw pointer, assigning anything to it is unsafe, not just a raw pointer parameter.  Shouldn't we just entirely prohibit global or member variables that are raw pointers to a refcounted type?

Comment 2

[(no longer active)]

(In reply to :Aryeh Gregor from comment #1)
> What's the problem here?  If the variable you're assigning to is an
> nsRefPtr, it's safe.  If it's a raw pointer, assigning anything to it is
> unsafe, not just a raw pointer parameter.  Shouldn't we just entirely
> prohibit global or member variables that are raw pointers to a refcounted
> type?

Yes.  Bug 1114683 is for doing this for member variables.  This bug is for doing it for globals.