[Bug ada/29762] New: invalid index constraint causes GNAT to crash

["mayerff at studi dot informatik dot uni-stuttgart dot de" <gcc-bugzilla at gcc dot gnu dot org>]

I wanted to compile an Ada package I am writing as a student at the University
of Stuttgart, Germany.

The following happened:

$ gnatmake -gnaty3acefhiklmnrpt permutations.adb
gcc -c -gnaty3acefhiklmnrpt permutations.adb
+===========================GNAT BUG DETECTED==============================+
| 3.3 20040913 (GNAT for Mac OS X build 1650) (powerpc-unknown-darwin)     |
| Assert_Failure sinfo.adb:1593                                            |
| Error detected at permutations.adb:68:7                                  |
| Please submit a bug report; see http://gcc.gnu.org/bugs.html.            |
| Include the entire contents of this bug box in the report.               |
| Include the exact gcc or gnatmake command that you entered.              |
| Also include sources listed below in gnatchop format                     |
| concatenated together with no headers between files.                     |
+==========================================================================+

Please include these source files with error report

permutations.adb
permutations.ads
list may be incomplete
permutations.adb:80:23: (style) space required
compilation abandoned
gnatmake: "permutations.adb" compilation error


The source files:

permutations.adb:
--  FILE:    permutations.adb
--
--  PROJECT: Programmieruebungen, Uebungsblatt 02
--  VERSION: 1.0
--  DATE:    08 Nov 2006
--  AUTHOR:  Fritjof A. Mayer
--
------------------------------------------------------------------------------
--
--  PACKAGE BODY Permutations
--

package body Permutations is

   --  FUNCTION Next_Perm
   --  
   --  Originally written on 10 Nov 2005
   --  Blatt 2, Aufgabe 3, Programmierkurs I, WS05/06
   --  by Fritjof A. Mayer
   --
   --  Generates next permutation.
   --  Algorithm taken from "Einfuehrung in die Informatik I WS05/06"
   function Next_Perm (Perm : Permutation) return Permutation is
      Next_P : Permutation (Perm'Range) := Perm;
      I, J, K, Smallest, Trans : Natural;
      N : constant Natural := Perm'Last;
   begin
      --  search backwards for P (I) < P (I + 1)
      --  starting at I = N - 1
      I := N - 1;
      while I >= 1 and Perm (I) > Perm (I + 1) loop
         I := I - 1;
      end loop;  
      --  search forwards for smallest Z > P (I), Z = P (J)
      --  starting at J = I + 1
      Smallest := I + 1;
      for J in (I + 1) .. N loop
         if Perm (J) < Perm (Smallest) and Perm (J) > Perm (I) then
            Smallest := J;
         end if;
      end loop;
      J := Smallest;
      --  swap P (I) and P (J) in next permutation
      Next_P (I) := Perm (J);
      Next_P (J) := Perm (I);
      --  sort elements P (I + 1) .. P (N) 
      --  by inverting their sequence
      K := 0;
      while (I + 1) + K < N - K loop
         Trans := Next_P ((I + 1) + K);
         Next_P ((I + 1) + K) := Next_P (N - K);
         Next_P (N - K) := Trans;     
         K := K + 1;
      end loop;
      return Next_P;
   end Next_Perm;



   --  FUNCTION Word_Perm
   -- 
   --  Generates all permutations of a word, first and last 
   --  character are not permuted
   --
   --  Example: ...
   --
   function Word_Perm (Word : String) return P_Words is
      All_Perms : P_Words (1 .. (Word'Length - 2)**2, Word'Length);
      Perm : Permutation (1 .. Word'Length - 2);
   begin
      for I in Perm'Range loop
         Perm (I) := I;
      end loop;

      for I in All_Perms'Range loop
         All_Perms (I, 1) := Word (Word'First);
         for J in Perm'Range loop
            All_Perms (I, J) := Word (Perm (J));
         end loop;
         All_Perms (I,Word'Length) := Word (Word'Last);
         Perm := Next_Perm (Perm);
      end loop;
      return All_Perms;
   end Word_Perm;


end Permutations;



permutations.ads:
package Permutations is
   type Permutation is array (Positive range <>) of Positive; 
   type P_Words is array (Positive range <>, Positive range <>) of Character;

   function Next_Perm (Perm : Permutation) return Permutation;


end Permutations;


----------------------------------------------------------------
----------------------------------------------------------------

I think the problem is here:
...
   function Word_Perm (Word : String) return P_Words is
      All_Perms : P_Words (1 .. (Word'Length - 2)**2, Word'Length);
      Perm : Permutation (1 .. Word'Length - 2);
   begin
...

P_Words needs index constraints, those are ranges.

   1 .. (Word'Length - 2)**2 is a range
   Word'Length is just a number and no range.

Normally i should receive an error message: invalid index constraint

When I change this to

      All_Perms : P_Words (1 .. (Word'Length - 2)**2, 
                            1 .. Word'Length);

it compiles without errors.


-- 
           Summary: invalid index constraint causes GNAT to crash
           Product: gcc
           Version: 3.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ada
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: mayerff at studi dot informatik dot uni-stuttgart dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=29762