Al Viro wrote:-
> gcc integer constant expressions handling is a bad joke.
>
> extern int n;
> struct {
> int x : 1 + n - n;
> } y;
>
> passes with -pedantic -std=c99. Replacing that with 1 + n - n + n - n
> is still OK with gcc; 1 + n + n - n - n is not.
>
> So that's hardly an example of, well, anything.
Consistency? :-) I wasn't aware of the quirk of the second example.
Apparently these expressions are only folded if their net result
is obvious as parsed by the grammar. Fixing this in GCC is a
horrendous amount of work; so much internal logic relies on this
early simplification, which is why it's not been done I guess.
Neil.
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