c++/modules: Fix ADL [PR117658]

On looking again at [basic.lookup.argdep] p4, I believe GCC hasn't fully
implemented the wording here for ADL.  This patch fixes two issues.

First, 4.3 indicates that a function exported from a named module should
be visible to ADL regardless of whether it's visible to normal name
lookup, as long as some restrictions are followed.

This patch implements this; for skipping declarations that "do not
appear in the TU containing the point of lookup" I don't think there's
anything special we need to do, as any declarations before the point of
lookup will be found in other ways anyway, and any remaining
declarations from the current TU cannot be seen regardless.

Secondly, currently we only add the exported functions along the
instantiation path of a lookup.  But I don't think this is intended by
the current wording, so this patch adjusts that.  I also clean up the
logic to do all different module processing in adl_namespace_fns so that
we don't duplicate work in traversing the module binding list
unnecessarily.

This new handling means we need to do some extra work to properly error
on overload sets containing TU-local entities (as this might actually
come up now!) but I'm leaving that for a later patch.

As a drive-by fix this also fixes an ICE for C++26 expansion statements
with finding the instantiation path.

	PR c++/117658

gcc/cp/ChangeLog:

	* cp-tree.h (get_originating_module): Adjust parameter names.
	* module.cc (path_of_instantiation): Handle C++26 expansion
	statements.
	* name-lookup.cc (name_lookup::adl_namespace_fns): Handle
	exported declarations attached to the same module of an
	associated entity with the same innermost non-inline namespace,
	and non-exported functions on the instantiation path.
	(name_lookup::search_adl): Build mapping of namespace to modules
	that associated entities are attached to; remove now-unneeded
	instantiation path handling.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/adl-4_a.C: Test should pass.
	* g++.dg/modules/adl-4_b.C: Test should pass.
	* g++.dg/modules/adl-6_a.C: New test.
	* g++.dg/modules/adl-6_b.C: New test.
	* g++.dg/modules/adl-6_c.C: New test.
	* g++.dg/modules/adl-7_a.C: New test.
	* g++.dg/modules/adl-7_b.C: New test.
	* g++.dg/modules/adl-7_c.C: New test.
	* g++.dg/modules/adl-8_a.C: New test.
	* g++.dg/modules/adl-8_b.C: New test.
	* g++.dg/modules/adl-8_c.C: New test.

Signed-off-by: Nathaniel Shead <nathanieloshead@gmail.com>
Reviewed-by: Jason Merrill <jason@redhat.com>

0 files changed, 0 insertions, 0 deletions