Martin Lucina writes: > aph@xxxxxxxxxx said: > > Please read the actual standard too. The rules about pointer type > > conversions are at 6.3.2.3. The appropriate paragraphs are paragraphs > > 1 and 7. > > So according to paragraph 1, the following is legal (obviously, this is > basic C): > > void *return_item (int *rc); > > ... > item_t *item_p; > int rc; > > item_p = return_item (&rc); > > but the case > > int return_item (void **item_p); > > ... > item_t *item_p; > int rc; > > rc = return_item ((void **)&item_p); > > is not legal since (void **) doesn't fall under the specification of > paragraph 1, but will work fine as long as item_p is only ever > dereferenced as an item_t? Well, the phrases "is not legal" and "will work fine" are clearly contradictory! It can't be both. > In other words, (void *) is convertible to any incomplete or object > type, but (void **) is not, despite the fact that *(void **) is a (void *)? That's right. > > (unless you cast it back to its original type first). This warning > > should be interpreted as saying that your interfaces are badly designed, > > and the correct way to avoid the warning is to redesign them in a way > > where you do not need to cast between conflicting types. (Even if you > > Unfortunately I can't change the interfaces since they're used by > legacy code. I'd just like to get rid of the warnings since if > people get used to ignoring the warnings in this code then they are > likely to miss other more important problems. -fno-strict-aliasing will do that, but will disable some optimizations. Your call. Andrew.
