From: Nathan Sidwell <nathan@acm.org>
Date: Tue, 22 Sep 2020 16:00:20 +0000 (-0700)
Subject: c++: fix injected friend of template class
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=7dfffe32419a963660f5c04b40b8f0becd509b69;p=gcc.git

c++: fix injected friend of template class

In working on fixing hiddenness, I discovered some suspicious code in
template instantiation.  I suspect it dates from when we didn't do the
hidden friend injection thing at all.  The xreftag finds the same
class, but makes it visible to name lookup.  Which is wrong.
hurrah, fixing a bug by deleting code!

	gcc/cp/
	* pt.c (instantiate_class_template_1): Do not repush and unhide
	injected friend.
	gcc/testsuite/
	* g++.old-deja/g++.pt/friend34.C: Check injected friend is still
	invisible.
---

diff --git a/gcc/cp/pt.c b/gcc/cp/pt.c
index 97d0c245f7e..44ca14afc4e 100644
--- a/gcc/cp/pt.c
+++ b/gcc/cp/pt.c
@@ -12030,25 +12030,6 @@ instantiate_class_template_1 (tree type)
 		    adjust_processing_template_decl = true;
 		  --processing_template_decl;
 		}
-	      else if (TREE_CODE (friend_type) != BOUND_TEMPLATE_TEMPLATE_PARM
-		       && !CLASSTYPE_USE_TEMPLATE (friend_type)
-		       && TYPE_HIDDEN_P (friend_type))
-		{
-		  /* friend class C;
-
-		     where C hasn't been declared yet.  Let's lookup name
-		     from namespace scope directly, bypassing any name that
-		     come from dependent base class.  */
-		  tree ns = decl_namespace_context (TYPE_MAIN_DECL (friend_type));
-
-		  /* The call to xref_tag_from_type does injection for friend
-		     classes.  */
-		  push_nested_namespace (ns);
-		  friend_type =
-		    xref_tag_from_type (friend_type, NULL_TREE,
-					/*tag_scope=*/ts_current);
-		  pop_nested_namespace (ns);
-		}
 	      else if (uses_template_parms (friend_type))
 		/* friend class C<T>;  */
 		friend_type = tsubst (friend_type, args,
diff --git a/gcc/testsuite/g++.old-deja/g++.pt/friend34.C b/gcc/testsuite/g++.old-deja/g++.pt/friend34.C
index 5e80ab98b2e..dcd6df0ce55 100644
--- a/gcc/testsuite/g++.old-deja/g++.pt/friend34.C
+++ b/gcc/testsuite/g++.old-deja/g++.pt/friend34.C
@@ -6,9 +6,12 @@
 template <typename T = void>
 class bar {
 public:
-  friend class foo; // this is not bar::foo, it forward-declares ::foo
+  friend class foo; // this is not bar::foo, it injects hidden ::foo
   class foo {};
   bar() { foo(); } // but this should refer to bar::foo
 };
 
 bar<> baz;
+
+// We still have not made foo visible.
+foo *b;  // { dg-error "does not name a type" }