[Bug c++/99040] [modules] partitions & using declarations

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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99040

--- Comment #2 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:0c27fe96f812df76ca07272d3c68765bd1f9dc08

commit r11-7229-g0c27fe96f812df76ca07272d3c68765bd1f9dc08
Author: Nathan Sidwell <nathan@acm.org>
Date:   Fri Feb 12 06:55:49 2021 -0800

    c++: Register streamed-in decls when new [PR 99040]

    With modules one can have using-decls refering to their own scope.  This
    is the way to export things from the GMF or from an import.  The
    problem was I was using current_ns == CP_DECL_CONTEXT (decl) to
    determine whether a decl should be registered in a namespace level or
    not.  But that's an inadequate check and we ended up reregistering
    decls and creating a circular list.  We should be registering the decl
    when first encountered -- whether we bind it is orthogonal to that.

            PR c++/99040
            gcc/cp/
            * module.cc (trees_in::decl_value): Call add_module_namespace_decl
            for new namespace-scope entities.
            (module_state::read_cluster): Don't call add_module_decl here.
            * name-lookup.h (add_module_decl): Rename to ...
            (add_module_namespace_decl): ... this.
            * name-lookup.c (newbinding_bookkeeping): Move into ...
            (do_pushdecl): ... here.  Its only remaining caller.
            (add_module_decl): Rename to ...
            (add_module_namespace_decl): ... here.  Add checking-assert for
            circularity. Don't call newbinding_bookkeeping, just extern_c
            checking and incomplete var checking.
            gcc/testsuite/
            * g++.dg/modules/pr99040_a.C: New.
            * g++.dg/modules/pr99040_b.C: New.
            * g++.dg/modules/pr99040_c.C: New.
            * g++.dg/modules/pr99040_d.C: New.