https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93295
--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
commit 1a291106384cabc73da0bc0f457b1cd3a4015970
Author: Jason Merrill <ja...@redhat.com>
Date: Wed Nov 27 17:05:53 2019 -0500
Implement P1814R0, CTAD for alias templates.
This patch implements C++20 class template argument deduction for alias
templates, which works by a moderately arcane transformation of the
deduction guides for the underlying class template. When implementing it,
it seemed that I could simplify the rules in the draft a bit and get
essentially the same effect; I'll be emailing the committee to that effect
soon.
gcc/cp/
* pt.c (rewrite_tparm_list): Factor out of build_deduction_guide.
(maybe_aggr_guide): Check for copy-init here.
(alias_ctad_tweaks, deduction_guides_for): New.
(ctor_deduction_guides_for): Factor out of do_class_deduction.
(ctad_template_p): New.
* parser.c (cp_parser_simple_type_specifier): Use it.
* constraint.cc (append_constraint): New.
gcc/c-family/
* c-cppbuiltin.c (c_cpp_builtins): Update __cpp_deduction_guides.
From-SVN: r278786
