[gcc r13-298] [Ada] fix crash on Secondary_Stack_Size with discriminant

[gcc r13-298] [Ada] fix crash on Secondary_Stack_Size with discriminant

[Pierre-Marie de Rodat]

https://gcc.gnu.org/g:6281d36342c29cdd9acb32032f59bf440953c942

commit r13-298-g6281d36342c29cdd9acb32032f59bf440953c942
Author: Bob Duff <duff@adacore.com>
Date:   Fri Jan 28 14:40:27 2022 -0500

    [Ada] fix crash on Secondary_Stack_Size with discriminant
    
    This patch fixes a crash caused by specifying the Secondary_Stack_Size
    aspect of a task type as the value of a discriminant of the task type,
    and then declaring a record component whose type is the task type,
    constrained to a discriminant of the record.
    
    gcc/ada/
    
            * sem_ch3.adb (Get_Discr_Value): Copy the result. Otherwise, the
            "tree" can be malformed (a DAG, not a tree) because
            Get_Discr_Value could be returning some subtree already attached
            to the tree.

Diff:
---
 gcc/ada/sem_ch3.adb | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/gcc/ada/sem_ch3.adb b/gcc/ada/sem_ch3.adb
index 53b0ec994c9..d4464e2b8c9 100644
--- a/gcc/ada/sem_ch3.adb
+++ b/gcc/ada/sem_ch3.adb
@@ -13963,7 +13963,7 @@ package body Sem_Ch3 is
               or else D = CR_Discriminant (Discr_Id)
               or else Corresponding_Discriminant (D) = Discr_Id
             then
-               return Node (E);
+               return New_Copy_Tree (Node (E));
             end if;
 
             Next_Discriminant (D);
@@ -13987,7 +13987,7 @@ package body Sem_Ch3 is
             E := First_Elmt (Constraints);
             while Present (D) loop
                if D = Discr_Id then
-                  return Node (E);
+                  return New_Copy_Tree (Node (E));
                end if;
 
                Next_Discriminant (D);