[gcc r13-3140] c++: fix broken conversion in coroutines

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

https://gcc.gnu.org/g:0143b277c9b17215ab3d4b361e1aef431799e813

commit r13-3140-g0143b277c9b17215ab3d4b361e1aef431799e813
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Sep 30 10:04:22 2022 -0400

    c++: fix broken conversion in coroutines
    
    You can't use CONVERT_EXPR to convert between two class types.
    
    VIEW_CONVERT_EXPR takes liberties with the C++ type system, but is probably
    safe in this context.  Let's also only use it when the type isn't already
    what we want.
    
    gcc/cp/ChangeLog:
    
            * coroutines.cc (expand_one_await_expression): Change conversion
            to VIEW_CONVERT_EXPR.
            * cp-gimplify.cc (cp_genericize_r) [CONVERT_EXPR]: Add assert.

Diff:
---
 gcc/cp/coroutines.cc  | 5 ++++-
 gcc/cp/cp-gimplify.cc | 1 +
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index eca01abcb7a..60b846600b9 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -1728,7 +1728,10 @@ expand_one_await_expression (tree *stmt, tree *await_expr, void *d)
     }
   else
     {
-      r = build1_loc (loc, CONVERT_EXPR, void_coro_handle_type, suspend);
+      r = suspend;
+      if (!same_type_ignoring_top_level_qualifiers_p (susp_type,
+						      void_coro_handle_type))
+	r = build1_loc (loc, VIEW_CONVERT_EXPR, void_coro_handle_type, r);
       r = build2_loc (loc, INIT_EXPR, void_coro_handle_type, data->conthand, r);
       r = build1 (CONVERT_EXPR, void_type_node, r);
       append_to_statement_list (r, &body_list);
diff --git a/gcc/cp/cp-gimplify.cc b/gcc/cp/cp-gimplify.cc
index b4599fc34d8..5d26e59d098 100644
--- a/gcc/cp/cp-gimplify.cc
+++ b/gcc/cp/cp-gimplify.cc
@@ -1589,6 +1589,7 @@ cp_genericize_r (tree *stmt_p, int *walk_subtrees, void *data)
       break;
 
     case CONVERT_EXPR:
+      gcc_checking_assert (!AGGREGATE_TYPE_P (TREE_TYPE (stmt)));
       gcc_assert (!CONVERT_EXPR_VBASE_PATH (stmt));
       break;