https://gcc.gnu.org/g:948ea8766780f7e44f39ccde3f2436ac2fec80da
commit r16-62-g948ea8766780f7e44f39ccde3f2436ac2fec80da
Author: Nathaniel Shead <nathanielosh...@gmail.com>
Date: Mon Apr 21 19:58:03 2025 +1000
c++/modules: Find non-exported reachable decls when instantiating friend
classes [PR119863]
In r15-9029-geb26b667518c95, we started checking for conflicting
declarations with any reachable decl attached to the same originating
module. This exposed the issue in the PR, where we would always create
a new type even if a matching type existed in the original module.
This patch reworks lookup_imported_hidden_friend to handle this case
better, by first checking for any reachable decl in the attached module
before looking in the mergeable decl slots.
PR c++/119863
gcc/cp/ChangeLog:
* name-lookup.cc (get_mergeable_namespace_binding): Remove
no-longer-used function.
(lookup_imported_hidden_friend): Also look for hidden imported
decls in an attached decl's module.
gcc/testsuite/ChangeLog:
* g++.dg/modules/tpl-friend-18_a.C: New test.
* g++.dg/modules/tpl-friend-18_b.C: New test.
* g++.dg/modules/tpl-friend-18_c.C: New test.
Signed-off-by: Nathaniel Shead <nathanielosh...@gmail.com>
Diff:
---
gcc/cp/name-lookup.cc | 43 ++++++++++++++------------
gcc/testsuite/g++.dg/modules/tpl-friend-18_a.C | 25 +++++++++++++++
gcc/testsuite/g++.dg/modules/tpl-friend-18_b.C | 9 ++++++
gcc/testsuite/g++.dg/modules/tpl-friend-18_c.C | 10 ++++++
4 files changed, 67 insertions(+), 20 deletions(-)
diff --git a/gcc/cp/name-lookup.cc b/gcc/cp/name-lookup.cc
index 498126a191ab..165c26bb578e 100644
--- a/gcc/cp/name-lookup.cc
+++ b/gcc/cp/name-lookup.cc
@@ -4178,22 +4178,6 @@ mergeable_namespace_slots (tree ns, tree name, bool
is_attached, tree *vec)
return vslot;
}
-/* Retrieve the bindings for an existing mergeable entity in namespace
- NS slot NAME. Returns NULL if no such bindings exists. */
-
-static tree
-get_mergeable_namespace_binding (tree ns, tree name, bool is_attached)
-{
- tree *mslot = find_namespace_slot (ns, name, false);
- if (!mslot || !*mslot || TREE_CODE (*mslot) != BINDING_VECTOR)
- return NULL_TREE;
-
- tree *vslot = get_fixed_binding_slot
- (mslot, name, is_attached ? BINDING_SLOT_PARTITION : BINDING_SLOT_GLOBAL,
- false);
- return vslot ? *vslot : NULL_TREE;
-}
-
/* DECL is a new mergeable namespace-scope decl. Add it to the
mergeable entities on GSLOT. */
@@ -4574,9 +4558,9 @@ lookup_imported_hidden_friend (tree friend_tmpl)
lazy_load_pendings (friend_tmpl);
- tree bind = get_mergeable_namespace_binding
- (current_namespace, DECL_NAME (inner), DECL_MODULE_ATTACH_P (inner));
- if (!bind)
+ tree name = DECL_NAME (inner);
+ tree *slot = find_namespace_slot (current_namespace, name, false);
+ if (!slot || !*slot || TREE_CODE (*slot) != BINDING_VECTOR)
return NULL_TREE;
/* We're only interested in declarations attached to the same module
@@ -4584,9 +4568,28 @@ lookup_imported_hidden_friend (tree friend_tmpl)
int m = get_originating_module (friend_tmpl, /*global=-1*/true);
gcc_assert (m != 0);
+ /* First check whether there's a reachable declaration attached to the module
+ we're looking for. */
+ if (m > 0)
+ if (binding_slot *mslot = search_imported_binding_slot (slot, m))
+ {
+ if (mslot->is_lazy ())
+ lazy_load_binding (m, current_namespace, name, mslot);
+ for (ovl_iterator iter (*mslot); iter; ++iter)
+ if (DECL_CLASS_TEMPLATE_P (*iter))
+ return *iter;
+ }
+
+ /* Otherwise, look in the mergeable slots for this name, in case an importer
+ has already instantiated this declaration. */
+ tree *vslot = get_fixed_binding_slot
+ (slot, name, m > 0 ? BINDING_SLOT_PARTITION : BINDING_SLOT_GLOBAL, false);
+ if (!vslot || !*vslot)
+ return NULL_TREE;
+
/* There should be at most one class template from the module we're
looking for, return it. */
- for (ovl_iterator iter (bind); iter; ++iter)
+ for (ovl_iterator iter (*vslot); iter; ++iter)
if (DECL_CLASS_TEMPLATE_P (*iter)
&& get_originating_module (*iter, true) == m)
return *iter;
diff --git a/gcc/testsuite/g++.dg/modules/tpl-friend-18_a.C
b/gcc/testsuite/g++.dg/modules/tpl-friend-18_a.C
new file mode 100644
index 000000000000..333c9764ce0e
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/tpl-friend-18_a.C
@@ -0,0 +1,25 @@
+// PR c++/119863
+// { dg-additional-options "-fmodules" }
+// { dg-module-cmi A }
+
+export module A;
+
+template<typename>
+class T;
+
+template<typename>
+class U
+{
+ template<typename>
+ friend class T;
+};
+
+template<typename V>
+class T
+{
+ U<V> x = {};
+};
+
+export
+template<typename V>
+T<V> f(V) { return {}; }
diff --git a/gcc/testsuite/g++.dg/modules/tpl-friend-18_b.C
b/gcc/testsuite/g++.dg/modules/tpl-friend-18_b.C
new file mode 100644
index 000000000000..2e537edcd4dc
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/tpl-friend-18_b.C
@@ -0,0 +1,9 @@
+// PR c++/119863
+// { dg-additional-options "-fmodules" }
+// { dg-module-cmi B }
+
+export module B;
+
+// this should not be considered conflicting
+template <typename>
+class T;
diff --git a/gcc/testsuite/g++.dg/modules/tpl-friend-18_c.C
b/gcc/testsuite/g++.dg/modules/tpl-friend-18_c.C
new file mode 100644
index 000000000000..6c8d85b12901
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/tpl-friend-18_c.C
@@ -0,0 +1,10 @@
+// PR c++/119863
+// { dg-additional-options "-fmodules" }
+
+import A;
+import B;
+
+int main()
+{
+ auto const x = f(1);
+}
