[gcc r12-2159] [Ada] Fix violation of No_Implicit_Loops restriction for enumeration type

[gcc r12-2159] [Ada] Fix violation of No_Implicit_Loops restriction for enumeration type

[Pierre-Marie de Rodat]

https://gcc.gnu.org/g:a9c3a4975013a9c3e29c03af5a1d0772d81aba12

commit r12-2159-ga9c3a4975013a9c3e29c03af5a1d0772d81aba12
Author: Eric Botcazou <ebotcazou@adacore.com>
Date:   Mon May 31 16:32:14 2021 +0200

    [Ada] Fix violation of No_Implicit_Loops restriction for enumeration type
    
    gcc/ada/
    
            * exp_imgv.adb: Add with and use clause for Restrict and Rident.
            (Build_Enumeration_Image_Tables): Do not generate the hash function
            if the No_Implicit_Loops restriction is active.

Diff:
---
 gcc/ada/exp_imgv.adb | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/gcc/ada/exp_imgv.adb b/gcc/ada/exp_imgv.adb
index 6e17a5c452a..d2605fbe049 100644
--- a/gcc/ada/exp_imgv.adb
+++ b/gcc/ada/exp_imgv.adb
@@ -37,6 +37,8 @@ with Namet;          use Namet;
 with Nmake;          use Nmake;
 with Nlists;         use Nlists;
 with Opt;            use Opt;
+with Restrict;       use Restrict;
+with Rident;         use Rident;
 with Rtsfind;        use Rtsfind;
 with Sem_Aux;        use Sem_Aux;
 with Sem_Res;        use Sem_Res;
@@ -160,6 +162,8 @@ package body Exp_Imgv is
              Expression          => Make_Aggregate (Loc, Expressions => V)));
       end Append_Table_To;
 
+   --  Start of Build_Enumeration_Image_Tables
+
    begin
       --  Nothing to do for types other than a root enumeration type
 
@@ -247,7 +251,7 @@ package body Exp_Imgv is
       Append_Table_To (Act, Eind, Nlit, Ityp, Ind);
 
       --  If the number of literals is not greater than Threshold, then we are
-      --  done. Otherwise we compute a (perfect) hash function for use by the
+      --  done. Otherwise we generate a (perfect) hash function for use by the
       --  Value attribute.
 
       if Nlit > Threshold then
@@ -283,11 +287,12 @@ package body Exp_Imgv is
 
          --  If the unit where the type is declared is the main unit, and the
          --  number of literals is greater than Threshold_For_Size when we are
-         --  optimizing for size, and -gnatd_h is not specified, try to compute
-         --  the hash function.
+         --  optimizing for size, and the restriction No_Implicit_Loops is not
+         --  active, and -gnatd_h is not specified, generate the hash function.
 
          if In_Main_Unit
            and then (Optimize_Size = 0 or else Nlit > Threshold_For_Size)
+           and then not Restriction_Active (No_Implicit_Loops)
            and then not Debug_Flag_Underscore_H
          then
             declare