[gcc r13-1497] [Ada] Couple of small cleanups for Cloned_Subtype

[Pierre-Marie de Rodat <pmderodat@gcc.gnu.org>]

https://gcc.gnu.org/g:d2672ffea0a478b265f5ed0239723c8ba54e8d24

commit r13-1497-gd2672ffea0a478b265f5ed0239723c8ba54e8d24
Author: Eric Botcazou <ebotcazou@adacore.com>
Date:   Thu Jun 9 00:24:34 2022 +0200

    [Ada] Couple of small cleanups for Cloned_Subtype
    
    No functional changes.
    
    gcc/ada/
    
            * exp_util.adb (Make_Subtype_From_Expr): Do not set field to Empty.
            * sem_util.adb (Visit_Itype): Remove ??? comment.

Diff:
---
 gcc/ada/exp_util.adb | 9 ++++-----
 gcc/ada/sem_util.adb | 3 +--
 2 files changed, 5 insertions(+), 7 deletions(-)

diff --git a/gcc/ada/exp_util.adb b/gcc/ada/exp_util.adb
index eaf7ebf8561..8557e4bb4bd 100644
--- a/gcc/ada/exp_util.adb
+++ b/gcc/ada/exp_util.adb
@@ -10213,8 +10213,8 @@ package body Exp_Util is
 
       elsif Is_Class_Wide_Type (Unc_Typ) then
          declare
-            CW_Subtype : Entity_Id;
-            EQ_Typ     : Entity_Id := Empty;
+            CW_Subtype : constant Entity_Id :=
+                           New_Class_Wide_Subtype (Unc_Typ, E);
 
          begin
             --  A class-wide equivalent type is not needed on VM targets
@@ -10237,11 +10237,10 @@ package body Exp_Util is
                   Set_Etype (Unc_Typ, Base_Type (Full_View (Etype (Unc_Typ))));
                end if;
 
-               EQ_Typ := Make_CW_Equivalent_Type (Unc_Typ, E);
+               Set_Equivalent_Type
+                 (CW_Subtype, Make_CW_Equivalent_Type (Unc_Typ, E));
             end if;
 
-            CW_Subtype := New_Class_Wide_Subtype (Unc_Typ, E);
-            Set_Equivalent_Type (CW_Subtype, EQ_Typ);
             Set_Cloned_Subtype (CW_Subtype, Base_Type (Unc_Typ));
 
             return New_Occurrence_Of (CW_Subtype, Loc);
diff --git a/gcc/ada/sem_util.adb b/gcc/ada/sem_util.adb
index df9fed1c159..edb948234ab 100644
--- a/gcc/ada/sem_util.adb
+++ b/gcc/ada/sem_util.adb
@@ -25146,8 +25146,7 @@ package body Sem_Util is
          end if;
 
          --  If a record subtype is simply copied, the entity list will be
-         --  shared. Thus cloned_Subtype must be set to indicate the sharing.
-         --  ??? What does this do?
+         --  shared, so Cloned_Subtype must be set to indicate this.
 
          if Ekind (Itype) in E_Class_Wide_Subtype | E_Record_Subtype then
             Set_Cloned_Subtype (New_Itype, Itype);