[gcc r12-2162] [Ada] Spurious style message on missing overriding indicator

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

https://gcc.gnu.org/g:99d6c1f8c29da41c33059024ff7494834b3bfbdc

commit r12-2162-g99d6c1f8c29da41c33059024ff7494834b3bfbdc
Author: Ed Schonberg <schonberg@adacore.com>
Date:   Sat May 29 10:14:46 2021 -0400

    [Ada] Spurious style message on missing overriding indicator
    
    gcc/ada/
    
            * style.adb (Missing_Overriding): Do not emit message when
            parent of subprogram is a full type declaration.

Diff:
---
 gcc/ada/style.adb | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/gcc/ada/style.adb b/gcc/ada/style.adb
index 1409cc61d19..c2bff83c9c6 100644
--- a/gcc/ada/style.adb
+++ b/gcc/ada/style.adb
@@ -265,11 +265,15 @@ package body Style is
       --  indicators were introduced in Ada 2005. We apply Comes_From_Source
       --  to Original_Node to catch the case of a procedure body declared with
       --  "is null" that has been rewritten as a normal empty body.
+      --  We do not emit a warning on an inherited operation that comes from
+      --  a type derivation.
 
       if Style_Check_Missing_Overriding
         and then (Comes_From_Source (Original_Node (N))
                    or else Is_Generic_Instance (E))
         and then Ada_Version_Explicit >= Ada_2005
+        and then Present (Parent (E))
+        and then Nkind (Parent (E)) /= N_Full_Type_Declaration
       then
          --  If the subprogram is an instantiation,  its declaration appears
          --  within a wrapper package that precedes the instance node. Place