r278786 - in /trunk/gcc: c-family/ChangeLog c-f...

[jason@gcc.gnu.org]

Author: jason
Date: Wed Nov 27 22:05:53 2019
New Revision: 278786

URL: https://gcc.gnu.org/viewcvs?rev=278786&root=gcc&view=rev
Log:
	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.

Added:
    trunk/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias1.C
    trunk/gcc/testsuite/g++.dg/cpp2a/class-deduction-alias2.C
Modified:
    trunk/gcc/c-family/ChangeLog
    trunk/gcc/c-family/c-cppbuiltin.c
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/call.c
    trunk/gcc/cp/constraint.cc
    trunk/gcc/cp/cp-tree.h
    trunk/gcc/cp/parser.c
    trunk/gcc/cp/pt.c
    trunk/gcc/cp/tree.c
    trunk/gcc/testsuite/g++.dg/cpp1z/class-deduction46.C
    trunk/gcc/testsuite/g++.dg/cpp2a/explicit11.C
    trunk/gcc/testsuite/g++.dg/cpp2a/feat-cxx2a.C