[gcc r12-2160] [Ada] Spurious warning in generic instance

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

https://gcc.gnu.org/g:629c82d729f1439718aa3759416cdb6cb03052f1

commit r12-2160-g629c82d729f1439718aa3759416cdb6cb03052f1
Author: Arnaud Charlet <charlet@adacore.com>
Date:   Fri May 28 10:25:39 2021 -0400

    [Ada] Spurious warning in generic instance
    
    gcc/ada/
    
            * sem_util.ads, sem_util.adb
            (Apply_Compile_Time_Constraint_Error): New parameter
            Emit_Message.
            * sem_ch4.adb (Analyze_Selected_Component): Disable warning
            within an instance.

Diff:
---
 gcc/ada/sem_ch4.adb  |  4 +++-
 gcc/ada/sem_util.adb | 21 ++++++++++++---------
 gcc/ada/sem_util.ads | 16 +++++++++-------
 3 files changed, 24 insertions(+), 17 deletions(-)

diff --git a/gcc/ada/sem_ch4.adb b/gcc/ada/sem_ch4.adb
index 1bfd222301e..c052022886a 100644
--- a/gcc/ada/sem_ch4.adb
+++ b/gcc/ada/sem_ch4.adb
@@ -5471,7 +5471,9 @@ package body Sem_Ch4 is
                      Apply_Compile_Time_Constraint_Error
                        (N, "component not present in }??",
                         CE_Discriminant_Check_Failed,
-                        Ent => Prefix_Type);
+                        Ent          => Prefix_Type,
+                        Emit_Message =>
+                          SPARK_Mode = On or not In_Instance_Not_Visible);
                      return;
                   end if;
 
diff --git a/gcc/ada/sem_util.adb b/gcc/ada/sem_util.adb
index ba840291345..6fdacdcba23 100644
--- a/gcc/ada/sem_util.adb
+++ b/gcc/ada/sem_util.adb
@@ -1510,13 +1510,14 @@ package body Sem_Util is
    -----------------------------------------
 
    procedure Apply_Compile_Time_Constraint_Error
-     (N      : Node_Id;
-      Msg    : String;
-      Reason : RT_Exception_Code;
-      Ent    : Entity_Id  := Empty;
-      Typ    : Entity_Id  := Empty;
-      Loc    : Source_Ptr := No_Location;
-      Warn   : Boolean    := False)
+     (N            : Node_Id;
+      Msg          : String;
+      Reason       : RT_Exception_Code;
+      Ent          : Entity_Id  := Empty;
+      Typ          : Entity_Id  := Empty;
+      Loc          : Source_Ptr := No_Location;
+      Warn         : Boolean    := False;
+      Emit_Message : Boolean    := True)
    is
       Stat   : constant Boolean := Is_Static_Expression (N);
       R_Stat : constant Node_Id :=
@@ -1530,8 +1531,10 @@ package body Sem_Util is
          Rtyp := Typ;
       end if;
 
-      Discard_Node
-        (Compile_Time_Constraint_Error (N, Msg, Ent, Loc, Warn => Warn));
+      if Emit_Message then
+         Discard_Node
+           (Compile_Time_Constraint_Error (N, Msg, Ent, Loc, Warn => Warn));
+      end if;
 
       --  Now we replace the node by an N_Raise_Constraint_Error node
       --  This does not need reanalyzing, so set it as analyzed now.
diff --git a/gcc/ada/sem_util.ads b/gcc/ada/sem_util.ads
index fb8309f4a2b..440ac800c11 100644
--- a/gcc/ada/sem_util.ads
+++ b/gcc/ada/sem_util.ads
@@ -161,13 +161,14 @@ package Sem_Util is
    --  part of the current package.
 
    procedure Apply_Compile_Time_Constraint_Error
-     (N      : Node_Id;
-      Msg    : String;
-      Reason : RT_Exception_Code;
-      Ent    : Entity_Id  := Empty;
-      Typ    : Entity_Id  := Empty;
-      Loc    : Source_Ptr := No_Location;
-      Warn   : Boolean    := False);
+     (N            : Node_Id;
+      Msg          : String;
+      Reason       : RT_Exception_Code;
+      Ent          : Entity_Id  := Empty;
+      Typ          : Entity_Id  := Empty;
+      Loc          : Source_Ptr := No_Location;
+      Warn         : Boolean    := False;
+      Emit_Message : Boolean    := True);
    --  N is a subexpression that will raise Constraint_Error when evaluated
    --  at run time. Msg is a message that explains the reason for raising the
    --  exception. The last character is ? if the message is always a warning,
@@ -189,6 +190,7 @@ package Sem_Util is
    --  when the caller wants to parameterize whether an error or warning is
    --  given), or when the message should be treated as a warning even when
    --  SPARK_Mode is On (which otherwise would force an error).
+   --  If Emit_Message is False, then do not emit any message.
 
    function Async_Readers_Enabled (Id : Entity_Id) return Boolean;
    --  Id should be the entity of a state abstraction, an object, or a type.