gcc/testsuite/gnat.dg/view_conversion1.adb

   1 -- { dg-do run }
   2 -- { dg-options "-gnatws" }
   3
   4 procedure View_Conversion1 is
   5
   6    type Matrix is array (Integer range <>, Integer range <>) of Float;
   7
   8    S1 : Matrix (-3 .. -2, 2 .. 3) := ((2.0, -1.0), (-1.0, 2.0));
   9    S2 : Matrix (1 .. 2, 1 .. 2) := S1;
  10    S3 : Matrix (2 .. 3, -3 .. -2);
  11    S4 : Matrix (1 .. 2, 1 .. 2);
  12
  13    function Normal_Last (A : Matrix; N : Natural) return Boolean is
  14    begin
  15       if A'Last (1) = N and then A'Last (2) = N then
  16          return True;
  17       else
  18          return False;
  19       end if;
  20    end;
  21
  22    procedure Transpose (A : Matrix; B : out Matrix) is
  23       N : constant Natural := A'Length (1);
  24       subtype Normal_Matrix is Matrix (1 .. N, 1 .. N);
  25    begin
  26       if not Normal_Last (A, N) or else not Normal_Last (B, N) then
  27          Transpose (Normal_Matrix (A), Normal_Matrix (B));
  28          return;
  29       end if;
  30
  31       for J in 1 .. N loop
  32          for K in 1 .. N loop
  33             B (J, K) := A (K, J);
  34          end loop;
  35       end loop;
  36    end;
  37
  38 begin
  39    Transpose (S1, S3);
  40    Transpose (S3, S4);
  41
  42    if S4 /= S2 then
  43       raise Program_Error;
  44    end if;
  45 end;