Re: [PATCH] c++: redundant targ coercion for var/alias tmpls

[Jason Merrill <jason@redhat.com>]

On 6/23/23 12:23, Patrick Palka wrote:
> On Fri, 23 Jun 2023, Jason Merrill wrote:
> 
>> On 6/21/23 13:19, Patrick Palka wrote:
>>> When stepping through the variable/alias template specialization code
>>> paths, I noticed we perform template argument coercion twice: first from
>>> instantiate_alias_template / finish_template_variable and again from
>>> tsubst_decl (during instantiate_template).  It should suffice to perform
>>> coercion once.
>>>
>>> To that end patch elides this second coercion from tsubst_decl when
>>> possible.  We can't get rid of it completely because we don't always
>>> specialize a variable template from finish_template_variable: we could
>>> also be doing so directly from instantiate_template during variable
>>> template partial specialization selection, in which case the coercion
>>> from tsubst_decl would be the first and only coercion.
>>
>> Perhaps we should be coercing in lookup_template_variable rather than
>> finish_template_variable?
> 
> Ah yes, there's a patch for that at
> https://gcc.gnu.org/pipermail/gcc-patches/2023-May/617377.html :)

So after that patch, can we get rid of the second coercion completely?

Jason