[gcc r12-1523] [Ada] Fix Is_Volatile_Function for functions declared in protected bodies

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

https://gcc.gnu.org/g:ccf0dee109ba0c71ca2b6e093a874daf1671ecf0

commit r12-1523-gccf0dee109ba0c71ca2b6e093a874daf1671ecf0
Author: Piotr Trojanek <trojanek@adacore.com>
Date:   Wed Mar 3 21:19:39 2021 +0100

    [Ada] Fix Is_Volatile_Function for functions declared in protected bodies
    
    gcc/ada/
    
            * sem_util.adb (Is_Volatile_Function): Follow the exact wording
            of SPARK (regarding volatile functions) and Ada (regarding
            protected functions).

Diff:
---
 gcc/ada/sem_util.adb | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/gcc/ada/sem_util.adb b/gcc/ada/sem_util.adb
index 6376b4e6b62..6481d86a835 100644
--- a/gcc/ada/sem_util.adb
+++ b/gcc/ada/sem_util.adb
@@ -21105,9 +21105,11 @@ package body Sem_Util is
    begin
       pragma Assert (Ekind (Func_Id) in E_Function | E_Generic_Function);
 
-      --  A function declared within a protected type is volatile
+      --  A protected function is volatile
 
-      if Is_Protected_Type (Scope (Func_Id)) then
+      if Nkind (Parent (Unit_Declaration_Node (Func_Id))) =
+           N_Protected_Definition
+      then
          return True;
 
       --  An instance of Ada.Unchecked_Conversion is a volatile function if