IIUC 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 end up in turn defining
and exporting the hidden friend std::f without ever having opening
the enclosing namespace std within the module purview and thus
DECL_MODULE_PURVIEW_P (std_node) is false.
Note that 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 the fact that we predefine std via push_namespace
from cxx_init_decl_processing (which makes it look like we've opened the
namespace in the TU), whereas with another namespace we would instead
lazily obtain the NAMESPACE_DECL from add_imported_namespace.
Since templated frined functions are special in that they give us a way
to declare a new namespace-scope function without having to explicitly
open the namespace, this patch proposes to fix this issue by propagating
DECL_MODULE_PURVIEW_P from a friend function to the enclosing namespace
when instantiating the friend.
Tested on x86_64-pc-linux-gnu, does this look like the right fix? Other
solutions that seem to work are to set DECL_MODULE_PURVIEW_P on std_node
after the fact from declare_module, or simply to suppress the assert for
std_node.
PR c++/100134
gcc/cp/ChangeLog:
* pt.cc (tsubst_friend_function): Propagate DECL_MODULE_PURVIEW_P
from the new declaration to the enclosing namespace scope.
gcc/testsuite/ChangeLog:
* g++.dg/modules/tpl-friend-8_a.H: New test.
* g++.dg/modules/tpl-friend-8_b.C: New test.
---
gcc/cp/pt.cc | 7 +++++++
gcc/testsuite/g++.dg/modules/tpl-friend-8_a.H | 9 +++++++++
gcc/testsuite/g++.dg/modules/tpl-friend-8_b.C | 8 ++++++++
3 files changed, 24 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/modules/tpl-friend-8_a.H
create mode 100644 gcc/testsuite/g++.dg/modules/tpl-friend-8_b.C
diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index 5b9fc588a21..9e3085f3fa6 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -11448,6 +11448,13 @@ tsubst_friend_function (tree decl, tree args)
by duplicate_decls. */
new_friend = old_decl;
}
+
+ /* We've just added a new namespace-scope entity to the purview without
+ necessarily having opened the enclosing namespace, so make sure the
+ enclosing namespace is in the purview now too. */
+ if (TREE_CODE (DECL_CONTEXT (new_friend)) == NAMESPACE_DECL)
+ DECL_MODULE_PURVIEW_P (DECL_CONTEXT (new_friend))
+ |= DECL_MODULE_PURVIEW_P (STRIP_TEMPLATE (new_friend));
}
else
{
diff --git a/gcc/testsuite/g++.dg/modules/tpl-friend-8_a.H
b/gcc/testsuite/g++.dg/modules/tpl-friend-8_a.H
new file mode 100644
index 00000000000..bd2290460b5
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/tpl-friend-8_a.H
@@ -0,0 +1,9 @@
+// PR c++/100134
+// { dg-additional-options -fmodule-header }
+// { dg-module-cmi {} }
+
+namespace std {
+ template<class T> struct A {
+ friend void f(A) { }
+ };
+}
diff --git a/gcc/testsuite/g++.dg/modules/tpl-friend-8_b.C
b/gcc/testsuite/g++.dg/modules/tpl-friend-8_b.C
new file mode 100644
index 00000000000..76d7447c2eb
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/tpl-friend-8_b.C
@@ -0,0 +1,8 @@
+// PR c++/100134
+// { dg-additional-options -fmodules-ts }
+// { dg-module-cmi pr100134 }
+export module pr100134;
+
+import "tpl-friend-8_a.H";
+
+export std::A<int> a;
--
2.38.0.15.gbbe21b64a0
