On Fri, Dec 21, 2012 at 10:25 AM, Dodji Seketeli <do...@redhat.com> wrote:
> Gabriel Dos Reis <g...@integrable-solutions.net> writes:
>
>> The example is valid, but I am not sure I understand your
>> explanation...
>
> Ah, sorry. I realize just now that I haven't mentioned the initial
> erratic behaviour. Maybe that could have made my message easier to
> understand.
>
> So consider the test case of the message:
>
> 1 template<typename>
> 2 using A = int;
> 3
> 4 template<template<class> class>
> 5 struct B {};
> 6
> 7 B<A> b;
>
> test.cc:7:4: error: integral expression ‘A’ is not constant
> B<A> b;
> ^
> Followed by some irrelevant other error messages.
>
> As I was saying my earlier message, here, the TREE_TYPE of the
> template_decl A is an integer; so check_instantiated_arg takes it as
> if A is an integer value (a decl with integer type), and thus, should
> be a constant.
>
> The fix I am proposing is just to allow check_instantiated_arg to make
> the difference between a classical integer decl, and an alias template
> which type-id is an integer.
>
> --
> Dodji
Hi Dodji,
Thank you very much for the explanation; your previous message
makes sense to me now. The question I have is why are we
using TREE_TYPE of a TEMPLATE_DECL to represent the
current instantiation of a template alias? Should not we use
TEMPLATE_RESULT instead?
-- Gaby
