http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56004
--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-01-16
17:30:55 UTC ---
(In reply to comment #2)
> (In reply to comment #1)
> > As was explained on stackoverflow, this has nothing t odo with access
> > modifiers, as you can easily demonstrate by making everything public.
> >
> > _t has not been declared at the point where you try to use it, so the name
> > is
> > not in scope. What are you claiming is a bug?
>
> It might be my confusion but is that not altering modifiers ?
I don't know what you mean. Change "private" to "public", the code fails in
exactly the same way, therefore the problem is nothing to do with
accessibility.
> I am not sure why
> the initialisation list does not make the private member available (at least
> declared).
The init list is a *use* of the member, not a declaration. Ctor init lists are
part of the function body, so only parsed once the class is complete. You
could also use t_ in the constructor body, that doesn't mean it's in scope
outside that function body.
> On the clang mailing list this was hinted at as well, but I am not sure that
> this is a case where private: before public: does work and not vice versa
> although as I said it is very likely a c++ issue that I have just not come
> across yet (although I will remember as usual).
It has nothing to do with private vs public!
> Can you confirm why the _t is not available or declared when it is in the
> initialisation list ? does the decltype require earlier visibility than the
> ctr
> ?
See above. The init list is part of a function body. Function bodies are
processed when the class is complete, as though they were defined after the
class. Look:
struct A {
A() : i(0) { ++i; } // i is in scope
decltype(i) get(); // error, i not in scope
int i; // i declared here
decltype(i) get2(); // OK, i has been declared
};
This is equivalent to:
struct A {
A();
decltype(i) get(); // error, i not in scope
int i; // i declared here
decltype(i) get2(); // OK, i has been declared
};
A::A() : i(0) { ++i; } // OK, class is complete, i in scope.
In the first example the constructor can use 'i' in the init list and the ctor
body, that's OK. You can *not* use 'i' in a function signature before it's
declared. get() is an error, get2() is OK.
