http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51842
--- Comment #7 from Janne Blomqvist <jb at gcc dot gnu.org> 2012-01-13 11:44:05 UTC --- (In reply to comment #6) > (In reply to comment #5) > > Yes, and no. It is perhaps a better match for the current frontend logic of > > choosing a type equal to the pointer size, but semantically ptrdiff_t is the > > better choice for array indexing. > > OK. But then the logical step is to change the FE Yes. I didn't do it as part of my patch back in April last year, because I wasn't sure how to properly do it, and I didn't worry about supporting targets where sizeof(void*) != sizeof(ptrdiff_t). > - how about something like > the following? > > --- a/gcc/fortran/trans-types.c > +++ b/gcc/fortran/trans-types.c > @@ -576,10 +576,7 @@ gfc_init_kinds (void) > gfc_default_character_kind = gfc_character_kinds[0].kind; > gfc_character_storage_size = gfc_default_character_kind * 8; > > - /* Choose the integer kind the same size as "void*" for our index kind. */ > - gfc_index_integer_kind = POINTER_SIZE / 8; > - /* Pick a kind the same size as the C "int" type. */ > - gfc_c_int_kind = INT_TYPE_SIZE / 8; > + gfc_index_integer_kind = get_int_kind_from_name (PTRDIFF_TYPE); (Well, you probably don't want to remove the assignment to gfc_c_int_kind.) But otherwise, if this works, it looks ok. FWIW in c-family/c-common.c there is ptrdiff_type_node = TREE_TYPE (identifier_global_value (get_identifier (PTRDIFF_TYPE))); So if the above patch + our definition for the array index type node gfc_array_index_type = gfc_get_int_type (gfc_index_integer_kind); accomplishes the same thing, it looks Ok.