Re: GNAT.Regpat problem.

[Adam Beneschan <adam@irvine.com>]

On Mar 22, 11:35 am, "Peter C. Chapin" <PCha...@vtc.vsc.edu> wrote:
> I'm trying to use regular expressions in a program via the package
> GNAT.Regpat. Here is a reduced example:
>
> with Ada.Text_IO; use Ada.Text_IO;
> with GNAT.Regpat;
>
> procedure Check is
>     Matcher : GNAT.Regpat.Pattern_Matcher(10);
>
> begin
>     GNAT.Regpat.Compile(Matcher, "^[:space:]*xyzzy$");
>
> exception
>     when Storage_Error =>
>        Put_Line("Insufficient space in Pattern_Matcher");
>
> end Check;
>
> The documentation for package GNAT.Regpat says this about the Compile
> procedure I think I'm using: "This function [sic] raises Storage_Error if
> Matcher is too small to hold the resulting code (i.e. Matcher.Size has too
> small a value)."
>
> In the example above the size is intentionally set too small. My program
> fails with a PROGRAM_ERROR exception (EXCEPTION_ACCESS_VIOLATION). If I make
> the size of the Matcher just 1, the program hangs. If I make the size
> something reasonable, the program runs fine.
>
> So is this an issue with GNAT.Regpat? It seems like it does not honor its
> documentation. Perhaps I'm doing something wrong.

I'm not sure whether I'm working with the latest version.  However,
when I took the sources for this package from GNAT 4.5.2 and compiled
and ran them (with your test) using a different compiler, a slice
assignment in Emit_Class failed due to out-of-range bounds.  If that
range check were turned off, I can imagine that the result would be
havoc.

                                 -- Adam