[gcc r12-6471] [Ada] Include generic instance names in non-visible entity errors

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

https://gcc.gnu.org/g:10608753db567042934872db8447f13eb15b5f8b

commit r12-6471-g10608753db567042934872db8447f13eb15b5f8b
Author: Justin Squirek <squirek@adacore.com>
Date:   Thu Dec 23 02:27:43 2021 +0000

    [Ada] Include generic instance names in non-visible entity errors
    
    gcc/ada/
    
            * sem_ch8.adb (Nvis_Messages): Add generic instance name to
            error message.

Diff:
---
 gcc/ada/sem_ch8.adb | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/gcc/ada/sem_ch8.adb b/gcc/ada/sem_ch8.adb
index e5b019c3019..e5756029246 100644
--- a/gcc/ada/sem_ch8.adb
+++ b/gcc/ada/sem_ch8.adb
@@ -5689,8 +5689,27 @@ package body Sem_Ch8 is
                      null;
 
                   else
-                     Error_Msg_N -- CODEFIX
-                       ("non-visible declaration#!", N);
+                     --  When the entity comes from a generic instance the
+                     --  normal error message machinery will give the line
+                     --  number of the generic package and the location of
+                     --  the generic instance, but not the name of the
+                     --  the instance.
+
+                     --  So, in order to give more descriptive error messages
+                     --  in this case, we include the name of the generic
+                     --  package.
+
+                     if Is_Generic_Instance (Scope (Ent)) then
+                        Error_Msg_Name_1 := Chars (Scope (Ent));
+                        Error_Msg_N -- CODEFIX
+                          ("non-visible declaration from %#!", N);
+
+                     --  Otherwise print the message normally
+
+                     else
+                        Error_Msg_N -- CODEFIX
+                          ("non-visible declaration#!", N);
+                     end if;
 
                      if Ekind (Scope (Ent)) /= E_Generic_Package then
                         Found := True;