Hi Akim, In <https://lists.gnu.org/archive/html/bug-bison/2020-05/msg00102.html> you write: > > Le 3 mai 2020 à 17:17, Bruno Haible <[email protected]> a écrit : > > > > There are a couple of GCC warnings on IRIX (CC="gcc -mabi=n32"): > > > > 2) > > ../src/fixits.c: In function `fixits_run': > > ../src/fixits.c:129: warning: dereferencing type-punned pointer will break > > strict-aliasing rules > > > > Modern C rules wants f to be a 'const void *'. Inside the loop body, > > you can cast f to 'fixit const *' without danger. > > So I had installed this: > > - fixit const *f = NULL; > + void const *p = NULL; > gl_list_iterator_t iter = gl_list_iterator (fixits); > - while (gl_list_iterator_next (&iter, (const void**) &f, NULL)) > + while (gl_list_iterator_next (&iter, &p, NULL)) > { > + fixit const *f = p; > > > > Today we have more occurrences of this pattern that we have to fix, > but some of these items need the pointer to point to a non-const value, > so we need a const void * pointer, and still a cast. > > Would you accept a macro, say gl_list_mutable_iterator_next, where we > would pass a void** instead of const void**?
No, I don't want this. It's a madness, in C++, to have to write the same member function definition twice, due to 'const' differences. This madness should not propagate into our C code. In C, we don't need to have two functions which produce the exactly same machine code. C has sufficient means for guaranteeing that one copy of the code will do. > Of course mutable_iterator > gives the impression that it's the iterator which is mutable, but an > iterator must so obviously be mutable that I don't think it would be > much of an issue, and it's quite symmetrical with const_iterator. > It might have been less surprising to have the current gl_list_iterator_next > be about mutable values and use gl_list_const_iterator_next for readonly > iteration, but it's too late. Whether you call it mutable_iterator vs. iterator, or iterator vs. const_iterator, doesn't change the fact that it's a code duplication. Bruno
