[gcc r14-278] c++: local class in nested generic lambda [PR109241]

[Jason Merrill <jason@gcc.gnu.org>]

https://gcc.gnu.org/g:d60cbbfaa9a3ad3bd1f613be95add939c16fc9a1

commit r14-278-gd60cbbfaa9a3ad3bd1f613be95add939c16fc9a1
Author: Jason Merrill <jason@redhat.com>
Date:   Wed Mar 22 16:11:47 2023 -0400

    c++: local class in nested generic lambda [PR109241]
    
    The earlier fix for PR109241 avoided the crash by handling a type with no
    TREE_BINFO.  But we want to move toward doing the partial substitution of
    classes in generic lambdas, so let's take a step in that direction.
    
            PR c++/109241
    
    gcc/cp/ChangeLog:
    
            * pt.cc (instantiate_class_template): Do partially instantiate.
            (tsubst_expr): Do call complete_type for partial instantiations.

Diff:
---
 gcc/cp/pt.cc | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/gcc/cp/pt.cc b/gcc/cp/pt.cc
index e1c272b9817..93a055c66a1 100644
--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -12086,7 +12086,8 @@ instantiate_class_template (tree type)
     return error_mark_node;
 
   if (COMPLETE_OR_OPEN_TYPE_P (type)
-      || uses_template_parms (type))
+      || (uses_template_parms (type)
+	  && !TYPE_FUNCTION_SCOPE_P (type)))
     return type;
 
   /* Figure out which template is being instantiated.  */
@@ -19356,10 +19357,7 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 
     case TAG_DEFN:
       tmp = tsubst (TREE_TYPE (t), args, complain, NULL_TREE);
-      if (dependent_type_p (tmp))
-	/* This is a partial instantiation, try again when full.  */
-	add_stmt (build_min (TAG_DEFN, tmp));
-      else if (CLASS_TYPE_P (tmp))
+      if (CLASS_TYPE_P (tmp))
 	{
 	  /* Local classes are not independent templates; they are
 	     instantiated along with their containing function.  And this
@@ -19368,6 +19366,12 @@ tsubst_expr (tree t, tree args, tsubst_flags_t complain, tree in_decl)
 	  /* Closures are handled by the LAMBDA_EXPR.  */
 	  gcc_assert (!LAMBDA_TYPE_P (TREE_TYPE (t)));
 	  complete_type (tmp);
+	  if (dependent_type_p (tmp))
+	    {
+	      /* This is a partial instantiation, try again when full.  */
+	      add_stmt (build_min (TAG_DEFN, tmp));
+	      break;
+	    }
 	  tree save_ccp = current_class_ptr;
 	  tree save_ccr = current_class_ref;
 	  for (tree fld = TYPE_FIELDS (tmp); fld; fld = DECL_CHAIN (fld))