From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
	id 7EC2D3858D39; Tue,  3 Oct 2023 10:35:26 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 7EC2D3858D39
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1696329326;
	bh=AKoHNVHTx8en746RWj+mi/0zJDfj0beflIh91+orvno=;
	h=From:To:Subject:Date:From;
	b=vO1Fbro8qBEZh2QGHWP2s4VilNrZ72NaWIUZb8fZeD7ckDOTGX8AS6Tp7ujXmAOUJ
	 BdjWj9ibgoxZJha5s60cT9juirh3uTL1+SwROz2RvFqvKH9QsJtQ+pJk139Rbdnb1w
	 um9/Tlv1sm6xG7h1f+mH9Koz4avDBH6ihwyabn3I=
From: "gaius at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug modula2/111675] New: Incorrect parameter value passed when
 attempting to pass a field of a packed record as a parameter
Date: Tue, 03 Oct 2023 10:35:25 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: modula2
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: gaius at gcc dot gnu.org
X-Bugzilla-Status: UNCONFIRMED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: gaius at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: bug_id short_desc product version bug_status
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-111675-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111675

            Bug ID: 111675
           Summary: Incorrect parameter value passed when attempting to
                    pass a field of a packed record as a parameter
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: modula2
          Assignee: gaius at gcc dot gnu.org
          Reporter: gaius at gcc dot gnu.org
  Target Milestone: ---

Summary cannot pass a packed field by value to a procedure as it results in=
 a
garbled value.

Consider the example below, if compiled and run we get:

$ gm2 -g packedrecord3.mod
$ ./a.out
failed to pass 0 into test
$ gdb ./a.out
(gdb) break printf
(gdb) run
Breakpoint 3, __printf (format=3D0x402008 "failed to pass %d into test\n")=
=20
(gdb) where
#0  __printf (format=3D0x402008 "failed to pass %d into test\n") at printf.=
c:28
#1  0x0000000000401387 in test (s=3D36893488147419103232, level=3D0) at
packedrecord3.mod:25
#2  0x00000000004012ce in _M2_packedrecord3_init (argc=3D1, argv=3D0x7fffff=
ffe448,
envp=3D0x7fffffffe458) at packedrecord3.mod:47

oddly print sizeof s gives 16 !=20=20


module packedrecord3 ;  (*!m2iso+gm2*)

from libc import printf, exit ;

type
   subrange =3D [0..63] ;

   packedrec =3D record
                  <* bytealignment (0) *>
                  bool: boolean ;
                  col : (white, black) ;
                  sub : subrange ;
               end ;


var
   global: subrange ;
   pr    : packedrec ;


procedure test (s: subrange; level: cardinal) ;
begin
   if s # global
   then
      printf ("failed to pass %d into test\n", ord (s)) ;
      exit (1)
   end ;
   if level > 0
   then
      test (s, level-1)
   end
end test ;


begin
   if size (pr) # 1
   then
      printf ("test failed as size (pr) should be 1 not %d\n", size (pr)) ;
      exit (1)
   end ;
   for global :=3D min (subrange) to max (subrange) do
      test (global, 2)
   end ;
   for global :=3D min (subrange) to max (subrange) do
      pr.bool :=3D false ;
      pr.sub :=3D global ;
      test (pr.sub, 2)
   end
end packedrecord3.=