c++/modules: Also check conflicting internal-linkage entities

While investigating another issue I noticed that the condition in
check_module_override seems incorrect: the wording in [basic.link] p11
has no exceptions for internal-linkage entities.

gcc/cp/ChangeLog:

	* name-lookup.cc (check_module_override): Remove check for
	TREE_PUBLIC when checking mergeable entities.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/namespace-1_c.C: Adjust to expect errors.
	* g++.dg/modules/namespace-2_b.C: Likewise.
	* g++.dg/modules/namespace-3_a.C: Removed.
	* g++.dg/modules/namespace-3_b.C: Removed.

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

gcc/cp/name-lookup.cc

@@ -3882,7 +3882,7 @@ check_module_override (tree decl, tree mvec, bool hiding,
 	  }
       }
 
-  if (TREE_PUBLIC (scope) && TREE_PUBLIC (STRIP_TEMPLATE (decl))
+  if (TREE_PUBLIC (scope)
       /* Namespaces are dealt with specially in
 	 make_namespace_finish.  */
       && !(TREE_CODE (decl) == NAMESPACE_DECL && !DECL_NAMESPACE_ALIAS (decl)))

gcc/testsuite/g++.dg/modules/namespace-1_c.C

@@ -1,13 +1,7 @@
 // { dg-additional-options "-fmodules-ts" }
-// The indirect import of frob, with namespaces impl and ompl doesn't
-// affect us.
-static int impl;
+
+static int impl;  // IF but no diagnostic required: impl@Frob not reachable from here
+
 import Frink;
 
-static int ompl;
-
-void corge (int x)
-{
-  impl = x;
-  ompl = frab (x);
-}
+static int ompl;  // { dg-error "different kind" }

gcc/testsuite/g++.dg/modules/namespace-2_b.C

@@ -2,16 +2,5 @@
 
 import foo;
 
-static int also_not_exported; // ok
-
-void X ()
-{
-  implicit_export::bob ();
-}
-
+static int also_not_exported; // { dg-error "different kind" }
 static int implicit_export; // { dg-error "different kind" }
-
-void Y ()
-{
-  also_not_exported = 1;
-}

gcc/testsuite/g++.dg/modules/namespace-3_a.C

@@ -1,21 +0,0 @@
-// Check namespace needed only by internal reference is not made visible
-// { dg-additional-options "-fmodules-ts" }
-
-export module frob;
-// { dg-module-cmi frob }
-
-namespace silent 
-{
-  namespace inner 
-  {
-    static int X () 
-    {
-      return 1;
-    }
-  }
-}
-
-export int f (int y)
-{
-  return y + silent::inner::X ();
-}

gcc/testsuite/g++.dg/modules/namespace-3_b.C

@@ -1,12 +0,0 @@
-// { dg-additional-options "-fmodules-ts" }
-
-import frob;
-
-int x = silent; // { dg-error "not declared" }
-
-static int silent;
-
-int user ()
-{
-  return f (silent);
-}