c++: ICE with noexcept in class in member function [PR96623]

I discovered very strange code in inject_parm_decls:

   if (args && is_this_parameter (args))
     {
       gcc_checking_assert (current_class_ptr == NULL_TREE);
       current_class_ptr = NULL_TREE;

We are tripping up on the assert because when we call inject_parm_decls,
current_class_ptr is set to 'A'.  It was set by inject_this_parameter
after we've parsed the parameter-declaration-clause of the member
function foo.  It seems correct to set ccp/ccr to A::B when we're
late parsing the noexcept-specifiers of bar* functions in B, so that
this-> does the right thing.  Since inject_parm_decls doesn't expect
to see non-null ccp/ccr, reset it before calling inject_parm_decls.

gcc/cp/ChangeLog:

	PR c++/96623
	* parser.c (inject_parm_decls): Remove a redundant assignment.
	(cp_parser_class_specifier_1): Clear current_class_{ptr,ref}
	before calling inject_parm_decls.

gcc/testsuite/ChangeLog:

	PR c++/96623
	* g++.dg/cpp0x/noexcept64.C: New test.

2 files changed, 29 insertions, 5 deletions

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 4b2bca3..e0208d0 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -24710,7 +24710,6 @@ inject_parm_decls (tree decl)
   if (args && is_this_parameter (args))
     {
       gcc_checking_assert (current_class_ptr == NULL_TREE);
-      current_class_ptr = NULL_TREE;
       current_class_ref = cp_build_fold_indirect_ref (args);
       current_class_ptr = args;
     }
@@ -24967,7 +24966,6 @@ cp_parser_class_specifier_1 (cp_parser* parser)
       tree pushed_scope = NULL_TREE;
       unsigned ix;
       cp_default_arg_entry *e;
-      tree save_ccp, save_ccr;
 
       if (!type_definition_ok_p || any_erroneous_template_args_p (type))
 	{
@@ -25012,6 +25010,8 @@ cp_parser_class_specifier_1 (cp_parser* parser)
       /* If there are noexcept-specifiers that have not yet been processed,
 	 take care of them now.  Do this before processing NSDMIs as they
 	 may depend on noexcept-specifiers already having been processed.  */
+      tree save_ccp = current_class_ptr;
+      tree save_ccr = current_class_ref;
       FOR_EACH_VEC_SAFE_ELT (unparsed_noexcepts, ix, decl)
 	{
 	  tree ctx = DECL_CONTEXT (decl);
@@ -25029,7 +25029,9 @@ cp_parser_class_specifier_1 (cp_parser* parser)
 	  /* Make sure that any template parameters are in scope.  */
 	  maybe_begin_member_template_processing (decl);
 
-	  /* Make sure that any member-function parameters are in scope.  */
+	  /* Make sure that any member-function parameters are in scope.
+	     This function doesn't expect ccp to be set.  */
+	  current_class_ptr = current_class_ref = NULL_TREE;
 	  inject_parm_decls (decl);
 
 	  /* 'this' is not allowed in static member functions.  */
@@ -25065,8 +25067,6 @@ cp_parser_class_specifier_1 (cp_parser* parser)
       vec_safe_truncate (unparsed_noexcepts, 0);
 
       /* Now parse any NSDMIs.  */
-      save_ccp = current_class_ptr;
-      save_ccr = current_class_ref;
       FOR_EACH_VEC_SAFE_ELT (unparsed_nsdmis, ix, decl)
 	{
 	  if (class_type != DECL_CONTEXT (decl))
diff --git a/gcc/testsuite/g++.dg/cpp0x/noexcept64.C b/gcc/testsuite/g++.dg/cpp0x/noexcept64.C
new file mode 100644
index 0000000..8b7303c
--- /dev/null
+++ b/gcc/testsuite/g++.dg/cpp0x/noexcept64.C
@@ -0,0 +1,24 @@
+// PR c++/96623
+// { dg-do compile { target c++11 } }
+
+constexpr int x = 0;
+struct A {
+  int a1;
+  void foo (int p) {
+    int foovar;
+    struct B {
+      int b1;
+      void bar1 () noexcept(x);
+      void bar2 () noexcept(noexcept(this->b1));
+      void bar3 () noexcept(noexcept(this->b2));
+      void bar4 () noexcept(noexcept(a1));
+      void bar5 () noexcept(noexcept(a2));
+      void bar6 () noexcept(noexcept(b1));
+      void bar7 () noexcept(noexcept(b2));
+      void bar8 () noexcept(noexcept(foovar));
+      void bar9 () noexcept(noexcept(p));
+      int b2;
+    };
+  }
+  int a2;
+};