[pushed] c++: module std and exception_ptr

[Jason Merrill]

Tested x86_64-pc-linux-gnu, applying to trunk.

-- 8< --

exception_ptr.h contains

  namespace __exception_ptr
  {
    class exception_ptr;
  }
  using __exception_ptr::exception_ptr;

so when module std tries to 'export using std::exception_ptr', it names
another using-directive rather than the class directly, so __exception_ptr
is never explicitly opened in module purview.

gcc/cp/ChangeLog:

        * module.cc (depset::hash::add_binding_entity): Set
        DECL_MODULE_PURVIEW_P instead of asserting.

gcc/testsuite/ChangeLog:

        * g++.dg/modules/using-20_a.C: New test.
---
 gcc/cp/module.cc                          |  7 +++++--
 gcc/testsuite/g++.dg/modules/using-20_a.C | 14 ++++++++++++++
 2 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 gcc/testsuite/g++.dg/modules/using-20_a.C

diff --git a/gcc/cp/module.cc b/gcc/cp/module.cc
index 21fc85150c9..72e876cec18 100644
--- a/gcc/cp/module.cc
+++ b/gcc/cp/module.cc
@@ -13253,8 +13253,11 @@ depset::hash::add_binding_entity (tree decl, WMB_Flags 
flags, void *data_)
       data->met_namespace = true;
       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));
+         /* It contains an exported thing, so it is exported.
+            We used to assert DECL_MODULE_PURVIEW_P, but that fails for a
+            namespace like std::__exception_ptr which is never opened in
+            module purview; the exporting using finds another using.  */
+         DECL_MODULE_PURVIEW_P (decl) = true;
          DECL_MODULE_EXPORT_P (decl) = true;
        }
 
diff --git a/gcc/testsuite/g++.dg/modules/using-20_a.C 
b/gcc/testsuite/g++.dg/modules/using-20_a.C
new file mode 100644
index 00000000000..bb3bb6160f8
--- /dev/null
+++ b/gcc/testsuite/g++.dg/modules/using-20_a.C
@@ -0,0 +1,14 @@
+// { dg-additional-options "-fmodules-ts -fdump-lang-module 
-Wno-global-module" }
+// { dg-final { scan-lang-dump {Writing definition '::foo::bar::baz'} module } 
}
+
+module;
+namespace foo {
+  namespace bar {
+    struct baz { };
+  }
+  using bar::baz;
+}
+export module foo;
+namespace foo {
+  export using foo::baz;
+}

base-commit: 7bf072e87a03c9eaff9b7a1ac182537b70f0ba8e
-- 
2.44.0