[COMMITTED] ada: Error in prefix-notation call

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

From: Bob Duff <duff@adacore.com>

The compiler gives a wrong error for a call of the form X.Y(...)
when Y is inherited indirectly via an interface.

gcc/ada/

	* sem_ch4.adb (Is_Private_Overriding): Return True in the case
	where a primitive operation is publicly inherited but privately
	overridden.

Tested on x86_64-pc-linux-gnu, committed on master.

---
 gcc/ada/sem_ch4.adb | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/gcc/ada/sem_ch4.adb b/gcc/ada/sem_ch4.adb
index 50ba6c9c847..2f3dfe71590 100644
--- a/gcc/ada/sem_ch4.adb
+++ b/gcc/ada/sem_ch4.adb
@@ -10223,9 +10223,15 @@ package body Sem_Ch4 is
 
                elsif not Comes_From_Source (Visible_Op)
                  and then Alias (Visible_Op) = Op
-                 and then not Is_Hidden (Visible_Op)
                then
-                  return True;
+                  --  If Visible_Op or what it overrides is not hidden, then we
+                  --  have found what we're looking for.
+
+                  if not Is_Hidden (Visible_Op)
+                    or else not Is_Hidden (Overridden_Operation (Op))
+                  then
+                     return True;
+                  end if;
                end if;
 
                Visible_Op := Homonym (Visible_Op);
-- 
2.42.0