[gcc r13-3719] ada: Reject misplaced pragma Obsolescent

[Marc Poulhi?s <dkm@gcc.gnu.org>]

https://gcc.gnu.org/g:74056e9411e0457c33ff5546a3563edb9ed09c99

commit r13-3719-g74056e9411e0457c33ff5546a3563edb9ed09c99
Author: Piotr Trojanek <trojanek@adacore.com>
Date:   Wed Sep 7 15:02:04 2022 +0200

    ada: Reject misplaced pragma Obsolescent
    
    Pragma Obsolescent appearing before declaration was putting the
    Obsolescent flag on the Standard package, which is certainly wrong. The
    problem was that we relied on the Find_Lib_Unit_Name routine without
    sanitizing the pragma placement with Check_Valid_Library_Unit_Pragma.
    
    Part of cleaning up the warnings machinery to better handle references
    to unset objects.
    
    gcc/ada/
    
            * sem_prag.adb (Analyze_Pragma [Pragma_Obsolescent]): Reject
            misplaced pragma.

Diff:
---
 gcc/ada/sem_prag.adb | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/gcc/ada/sem_prag.adb b/gcc/ada/sem_prag.adb
index 60ea681001a..471ef870fa7 100644
--- a/gcc/ada/sem_prag.adb
+++ b/gcc/ada/sem_prag.adb
@@ -20502,10 +20502,16 @@ package body Sem_Prag is
 
             if No (Decl) then
 
-               --  First case: library level compilation unit declaration with
+               --  Case 0: library level compilation unit declaration with
+               --  the pragma preceding the declaration.
+
+               if Nkind (Parent (N)) = N_Compilation_Unit then
+                  Pragma_Misplaced;
+
+               --  Case 1: library level compilation unit declaration with
                --  the pragma immediately following the declaration.
 
-               if Nkind (Parent (N)) = N_Compilation_Unit_Aux then
+               elsif Nkind (Parent (N)) = N_Compilation_Unit_Aux then
                   Set_Obsolescent
                     (Defining_Entity (Unit (Parent (Parent (N)))));
                   return;