[Bug c++/99425] [modules] ICE tree check: expected tree_vec, have tree_list in lookup_template_class_1, at cp/pt.c:9803

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99425

--- Comment #3 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Nathan Sidwell <nathan@gcc.gnu.org>:

https://gcc.gnu.org/g:87e3c2ef682e2ba7692ee56142a4eb5b6441c4d3

commit r11-7765-g87e3c2ef682e2ba7692ee56142a4eb5b6441c4d3
Author: Nathan Sidwell <nathan@acm.org>
Date:   Thu Mar 18 05:12:59 2021 -0700

    c++: duplicate alias templates with decltype [PR 99425]

    This failure was ultimately from incorrect handling of alias
    templates, but required a specific set of occurrences to happen in the
    specialization hash table.  This cleans up the specialization
    streaming to add alias instantiations at the same point as other
    instantiations.  I also removed some unneeded global variables dealing
    with mapping of duplicate decl contexts.

            PR c++/99425
            gcc/cp/
            * cp-tree.h (map_context_from, map_context_to): Delete.
            (add_mergeable_specialization): Add is_alias parm.
            * pt.c (add_mergeable_specialization): Add is_alias parm, add them.
            * module.cc (map_context_from, map_context_to): Delete.
            (trees_in::decl_value): Add specializations later, adjust call.
            Drop useless alias lookup. Set duplicate fn parm context.
            (check_mergeable_decl): Drop context mapping.
            (trees_in::is_matching_decl): Likewise.
            (trees_in::read_function_def): Drop parameter context adjustment
            here.
            gcc/testsuite/
            * g++.dg/modules/pr99425-1.h: New.
            * g++.dg/modules/pr99425-1_a.H: New.
            * g++.dg/modules/pr99425-1_b.H: New.
            * g++.dg/modules/pr99425-1_c.C: New.
            * g++.dg/modules/pr99425-2_a.X: New.
            * g++.dg/modules/pr99425-2_b.X: New.
            * g++.dg/template/pr99425.C: New.