[gcc r12-5680] [Ada] Fix crash on pragma Compile_Time_Warning/Error

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

https://gcc.gnu.org/g:9ce9322ccc4aa873d732554c895b821c90017511

commit r12-5680-g9ce9322ccc4aa873d732554c895b821c90017511
Author: Bob Duff <duff@adacore.com>
Date:   Wed Nov 17 12:06:32 2021 -0500

    [Ada] Fix crash on pragma Compile_Time_Warning/Error
    
    gcc/ada/
    
            * sem_prag.adb (Process_Compile_Time_Warning_Or_Error): Do not
            follow the Corresponding_Spec pointer if Acts_As_Spec is True,
            because Corresponding_Spec is Empty in that case, so we would
            exit the loop prematurely, and incorrectly think we are not
            inside a generic unit when we are.

Diff:
---
 gcc/ada/sem_prag.adb | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/gcc/ada/sem_prag.adb b/gcc/ada/sem_prag.adb
index 1d5cc2535bd..9fdec53b374 100644
--- a/gcc/ada/sem_prag.adb
+++ b/gcc/ada/sem_prag.adb
@@ -7827,11 +7827,15 @@ package body Sem_Prag is
 
          if Compile_Time_Known_Value (Arg1x) then
             Validate_Compile_Time_Warning_Or_Error (N, Sloc (Arg1));
+
          else
             while Present (P) and then Nkind (P) not in N_Generic_Declaration
             loop
-               if Nkind (P) in N_Package_Body | N_Subprogram_Body then
-                  P := Corresponding_Spec (P);
+               if (Nkind (P) = N_Subprogram_Body and then not Acts_As_Spec (P))
+                 or else Nkind (P) = N_Package_Body
+               then
+                  P := Parent (Corresponding_Spec (P));
+
                else
                   P := Parent (P);
                end if;