[Bug c++/81660] Add -Wexceptions warning

["mpolacek at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81660

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Candidate patch:

--- a/gcc/cp/except.c
+++ b/gcc/cp/except.c
@@ -41,7 +41,6 @@ static tree do_allocate_exception (tree);
 static tree wrap_cleanups_r (tree *, int *, void *);
 static int complete_ptr_ref_or_void_ptr_p (tree, tree);
 static bool is_admissible_throw_operand_or_catch_parameter (tree, bool);
-static int can_convert_eh (tree, tree);

 /* Sets up all the global eh stuff that needs to be initialized at the
    start of compilation.  */
@@ -932,31 +931,34 @@ nothrow_libfn_p (const_tree fn)
 /* Returns nonzero if an exception of type FROM will be caught by a
    handler for type TO, as per [except.handle].  */

-static int
+static bool
 can_convert_eh (tree to, tree from)
 {
   to = non_reference (to);
   from = non_reference (from);

+  if (same_type_ignoring_top_level_qualifiers_p (to, from))
+    return true;
+
   if (TYPE_PTR_P (to) && TYPE_PTR_P (from))
     {
       to = TREE_TYPE (to);
       from = TREE_TYPE (from);

       if (! at_least_as_qualified_p (to, from))
-   return 0;
+   return false;

       if (VOID_TYPE_P (to))
-   return 1;
+   return true;

       /* Else fall through.  */
     }

   if (CLASS_TYPE_P (to) && CLASS_TYPE_P (from)
       && publicly_uniquely_derived_p (to, from))
-    return 1;
+    return true;

-  return 0;
+  return false;
 }

 /* Check whether any of the handlers in I are shadowed by another handler