[Bug c++/100134] [modules] ICE when using a vector in a module

["cvs-commit at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100134

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Patrick Palka <ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:9736a42e1fb8df30d72cf28594d9046bf50200c1

commit r13-3236-g9736a42e1fb8df30d72cf28594d9046bf50200c1
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue Oct 11 15:02:23 2022 -0400

    c++ modules: ICE with templated friend and std namespace [PR100134]

    The function depset::hash::add_binding_entity has an assert verifying
    that if a namespace contains an exported entity, then the namespace must
    have been opened in the module purview:

      if (data->hash->add_namespace_entities (decl, data->partitions))
        {
          /* It contains an exported thing, so it is exported.  */
          gcc_checking_assert (DECL_MODULE_PURVIEW_P (decl));
          DECL_MODULE_EXPORT_P (decl) = true;
        }

    We're tripping over this assert in the below testcase because by
    instantiating and exporting std::A<int>, we in turn define and export the
    hidden friend std::f(A<int>) without ever having opened the enclosing
    namespace std within the module purview, and thus DECL_MODULE_PURVIEW_P
    for std is false.

    It's important that the enclosing namespace is std here: if we use
    a different namespace then the ICE disappears.  This probably has
    something to do with us predefining std via push_namespace from
    cxx_init_decl_processing (which makes it look like we've opened it
    within the TU), whereas with another namespace we would instead lazily
    create its NAMESPACE_DECL from add_imported_namespace.

    Since templated friend functions are special in that they give us a way
    to introduce a namespace-scope function without having to explicitly
    open the namespace, this patch proposes to fix this ICE by propagating
    DECL_MODULE_PURVIEW_P from the introduced function to the enclosing
    namespace during tsubst_friend_function.

            PR c++/100134

    gcc/cp/ChangeLog:

            * pt.cc (tsubst_friend_function): Propagate DECL_MODULE_PURVIEW_P
            from the introduced namespace-scope function to the namespace.

    gcc/testsuite/ChangeLog:

            * g++.dg/modules/tpl-friend-8_a.H: New test.
            * g++.dg/modules/tpl-friend-8_b.C: New test.