[COMMITED] ada: Improve accessibility check generation

["Marc Poulhiès" <poulhies@adacore.com>]

From: Justin Squirek <squirek@adacore.com>

Improve accessibility check generation by more precisely identifying cases in
which an Original_Node call is needed.

Instead of grabbing the Original_Node of a prefix in all cases (since this
can cause issues where unanalyzed instance names get referenced) we only
obtain the original node when said prefix comes as a result of expanding
function calls.

gcc/ada/

	* sem_util.adb
	(Accessibility_Level): Modify indexed and selected components case
	by reducing the scope where Original_Node gets used.
---
 gcc/ada/sem_util.adb | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/gcc/ada/sem_util.adb b/gcc/ada/sem_util.adb
index b0babeb9d6f..c43a008ae5d 100644
--- a/gcc/ada/sem_util.adb
+++ b/gcc/ada/sem_util.adb
@@ -531,7 +531,7 @@ package body Sem_Util is
 
       --  Local variables
 
-      E   : Entity_Id := Original_Node (Expr);
+      E   : Node_Id := Original_Node (Expr);
       Pre : Node_Id;
 
    --  Start of processing for Accessibility_Level
@@ -777,8 +777,18 @@ package body Sem_Util is
 
          --  We don't handle function calls in prefix notation correctly ???
 
-         when N_Indexed_Component | N_Selected_Component =>
-            Pre := Original_Node (Prefix (E));
+         when N_Indexed_Component | N_Selected_Component | N_Slice =>
+            Pre := Prefix (E);
+
+            --  Fetch the original node when the prefix comes from the result
+            --  of expanding a function call since we want to find the level
+            --  of the original source call.
+
+            if not Comes_From_Source (Pre)
+              and then Nkind (Original_Node (Pre)) = N_Function_Call
+            then
+               Pre := Original_Node (Pre);
+            end if;
 
             --  When E is an indexed component or selected component and
             --  the current Expr is a function call, we know that we are
-- 
2.25.1