https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121209
--- Comment #7 from Halalaluyafail3 <luigighiron at gmail dot com> ---
(In reply to uecker from comment #6)
> (In reply to Halalaluyafail3 from comment #5)
> > Is it not required that the composite type of two types has to be the same
> > when obtaining it twice, or that the order is irrelevant?
>
> The intention was that this is not required. My plan was to propose a change
> to typedef so that this becomes irrelevant.
Even if typedef is changed it would still be relevant with structure and union
redefinitions in the same scope.
> > Here is an example
> > of where it could be an issue when not using typedef:
> >
> > #include<stdio.h>
> > enum A:int{a};
> > enum B:int{b};
> > int main(){
> > puts(_Generic(1?(enum A*)0:(int*)0,enum B*:"yes",default:"no"));
> > puts(_Generic(1?(enum A*)0:(int*)0,enum B*:"yes",default:"no"));
> > }
> >
> > Each call to puts prints yes if the composite type of enum A and int is int,
> > and no otherwise. If the composite type can change, then can this print both
> > yes and no, in either order?
>
> For enum and integer, it is implementation defined whether the composite type
> is the integer or the enum. So here it does not depend on the order but
> on how this is defined by the implementation.
So the implementation can define it to randomly choose whether to use the
enumerated type or the integer type?
