re PR c++/60573 ([c++1y] ICE with defining generic function of nested class in class scope)

Fix PR c++/60573

	PR c++/60573
	* name-lookup.h (cp_binding_level): New transient field defining_class_p
	to indicate whether a scope is in the process of defining a class.
	* semantics.c (begin_class_definition): Set defining_class_p.
	* name-lookup.c (leave_scope): Reset defining_class_p.
	* parser.c (synthesize_implicit_template_parm): Use cp_binding_level::
	defining_class_p rather than TYPE_BEING_DEFINED as the predicate for
	unwinding to class-defining scope to handle the erroneous definition of
	a generic function of an arbitrarily nested class within an enclosing
	class.

	PR c++/60573
	* g++.dg/cpp1y/pr60573.C: New testcase.

From-SVN: r208921

gcc/cp/ChangeLog

@@ -1,6 +1,20 @@
+2014-03-28  Adam Butcher  <adam@jessamine.co.uk>
+
+	PR c++/60573
+	* name-lookup.h (cp_binding_level): New transient field defining_class_p
+	to indicate whether a scope is in the process of defining a class.
+	* semantics.c (begin_class_definition): Set defining_class_p.
+	* name-lookup.c (leave_scope): Reset defining_class_p.
+	* parser.c (synthesize_implicit_template_parm): Use cp_binding_level::
+	defining_class_p rather than TYPE_BEING_DEFINED as the predicate for
+	unwinding to class-defining scope to handle the erroneous definition of
+	a generic function of an arbitrarily nested class within an enclosing
+	class.
+
 2014-03-26  Fabien Chêne  <fabien@gcc.gnu.org>
-        PR c++/52369
-        * cp/method.c (walk_field_subobs): improve the diagnostic
+
+	PR c++/52369
+	* cp/method.c (walk_field_subobs): improve the diagnostic
 	locations for both REFERENCE_TYPEs and non-static const members.
 	* cp/init.c (diagnose_uninitialized_cst_or_ref_member): use %q#D
 	instead of %qD to be consistent with the c++11 diagnostic.

gcc/cp/name-lookup.c

@@ -1630,10 +1630,14 @@ leave_scope (void)
       free_binding_level = scope;
     }
 
-  /* Find the innermost enclosing class scope, and reset
-     CLASS_BINDING_LEVEL appropriately.  */
   if (scope->kind == sk_class)
     {
+      /* Reset DEFINING_CLASS_P to allow for reuse of a
+	 class-defining scope in a non-defining context.  */
+      scope->defining_class_p = 0;
+
+      /* Find the innermost enclosing class scope, and reset
+	 CLASS_BINDING_LEVEL appropriately.  */
       class_binding_level = NULL;
       for (scope = current_binding_level; scope; scope = scope->level_chain)
 	if (scope->kind == sk_class)

gcc/cp/name-lookup.h

@@ -255,7 +255,14 @@ struct GTY(()) cp_binding_level {
   unsigned more_cleanups_ok : 1;
   unsigned have_cleanups : 1;
 
-  /* 24 bits left to fill a 32-bit word.  */
+  /* Transient state set if this scope is of sk_class kind
+     and is in the process of defining 'this_entity'.  Reset
+     on leaving the class definition to allow for the scope
+     to be subsequently re-used as a non-defining scope for
+     'this_entity'.  */
+  unsigned defining_class_p : 1;
+
+  /* 23 bits left to fill a 32-bit word.  */
 };
 
 /* The binding level currently in effect.  */

gcc/cp/parser.c

@@ -31999,7 +31999,7 @@ synthesize_implicit_template_parm  (cp_parser *parser)
 	{
 	  /* If not defining a class, then any class scope is a scope level in
 	     an out-of-line member definition.  In this case simply wind back
-	     beyond the first such scope to inject the template argument list.
+	     beyond the first such scope to inject the template parameter list.
 	     Otherwise wind back to the class being defined.  The latter can
 	     occur in class member friend declarations such as:
 
@@ -32010,12 +32010,23 @@ synthesize_implicit_template_parm  (cp_parser *parser)
 		 friend void A::foo (auto);
 	       };
 
-	    The template argument list synthesized for the friend declaration
-	    must be injected in the scope of 'B', just beyond the scope of 'A'
-	    introduced by 'A::'.  */
+	    The template parameter list synthesized for the friend declaration
+	    must be injected in the scope of 'B'.  This can also occur in
+	    erroneous cases such as:
 
-	  while (scope->kind == sk_class
-		 && !TYPE_BEING_DEFINED (scope->this_entity))
+	       struct A {
+	         struct B {
+		   void foo (auto);
+		 };
+		 void B::foo (auto) {}
+	       };
+
+	    Here the attempted definition of 'B::foo' within 'A' is ill-formed
+	    but, nevertheless, the template parameter list synthesized for the
+	    declarator should be injected into the scope of 'A' as if the
+	    ill-formed template was specified explicitly.  */
+
+	  while (scope->kind == sk_class && !scope->defining_class_p)
 	    {
 	      parent_scope = scope;
 	      scope = scope->level_chain;

gcc/cp/semantics.c

@@ -2777,6 +2777,7 @@ begin_class_definition (tree t)
   maybe_process_partial_specialization (t);
   pushclass (t);
   TYPE_BEING_DEFINED (t) = 1;
+  class_binding_level->defining_class_p = 1;
 
   if (flag_pack_struct)
     {

gcc/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2014-03-28  Adam Butcher  <adam@jessamine.co.uk>
+
+	PR c++/60573
+	* g++.dg/cpp1y/pr60573.C: New testcase.
+
 2014-03-28  Jakub Jelinek  <jakub@redhat.com>
 
 	PR target/60693

gcc/testsuite/g++.dg/cpp1y/pr60573.C

@@ -0,0 +1,28 @@
+// PR c++/60573
+// { dg-do compile { target c++1y } }
+// { dg-options "" }
+
+struct A
+{
+  struct B
+  {
+    void foo(auto);
+  };
+
+  void B::foo(auto) {}  // { dg-error "cannot define" }
+
+  struct X
+  {
+    struct Y
+    {
+      struct Z
+      {
+        void foo(auto);
+      };
+    };
+
+    void Y::Z::foo(auto) {}  // { dg-error "cannot define" }
+  };
+
+  void X::Y::Z::foo(auto) {}  // { dg-error "cannot define" }
+};