[Ada] Fix incorrect freezing with generic child unit

[Ada] Fix incorrect freezing with generic child unit

[Pierre-Marie de Rodat]

[-- Attachment #1: Type: text/plain, Size: 413 bytes --]

The Analyze_Associations.Check_Generic_Parent function was using an
incorrect node as the instanciation node for the actual, possibly
leading to incorrect freeze node being created (and later crashing in
gigi). Using Get_Unit_Instantiation_Node fixes the issue.

Tested on x86_64-pc-linux-gnu, committed on trunk

gcc/ada/

	* sem_ch12.adb (Check_Generic_Parent): Use
	Get_Unit_Instantiation_Node instead of Next.

[-- Attachment #2: patch.diff --]
[-- Type: text/x-diff, Size: 1042 bytes --]

diff --git a/gcc/ada/sem_ch12.adb b/gcc/ada/sem_ch12.adb
--- a/gcc/ada/sem_ch12.adb
+++ b/gcc/ada/sem_ch12.adb
@@ -1164,7 +1164,7 @@ package body Sem_Ch12 is
       function Matching_Actual
         (F   : Entity_Id;
          A_F : Entity_Id) return Node_Id;
-      --  Find actual that corresponds to a given a formal parameter. If the
+      --  Find actual that corresponds to a given formal parameter. If the
       --  actuals are positional, return the next one, if any. If the actuals
       --  are named, scan the parameter associations to find the right one.
       --  A_F is the corresponding entity in the analyzed generic, which is
@@ -2063,7 +2063,7 @@ package body Sem_Ch12 is
 
                         procedure Check_Generic_Parent is
                            Inst : constant Node_Id :=
-                                    Next (Unit_Declaration_Node (Actual));
+                                    Get_Unit_Instantiation_Node (Actual);
                            Par  : Entity_Id;
 
                         begin