https://gcc.gnu.org/bugzilla/show_bug.cgi?id=118589
Bug ID: 118589
Summary: Bug opaque type fields are visible outside
implementation module
Product: gcc
Version: 14.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: modula2
Assignee: gaius at gcc dot gnu.org
Reporter: gaius at gcc dot gnu.org
Target Milestone: ---
As reported on the gm2 mailing list:
Opaque type fields are visible outside the implementation module. Consider:
$ cat MinOpaque.def
DEFINITION MODULE MinOpaque;
TYPE Opaque;
PROCEDURE Make (VAR o: Opaque; i: INTEGER);
END MinOpaque.
$ cat MinOpaque.mod:
IMPLEMENTATION MODULE MinOpaque;
FROM Storage IMPORT ALLOCATE, DEALLOCATE;
FROM SYSTEM IMPORT TSIZE;
TYPE Opaque = POINTER TO INTEGER;
PROCEDURE Make (VAR o: Opaque; i: INTEGER);
BEGIN
ALLOCATE (o, TSIZE (Opaque));
o^ := i;
END Make;
END MinOpaque.
$ cat TryMinOpaque.mod
MODULE TryMinOpaque;
FROM InOut IMPORT WriteString, WriteLn, WriteInt;
FROM MinOpaque IMPORT Opaque, Make;
VAR o: Opaque;
BEGIN
Make (o, 10);
o^ := 20; (* I thought this was illegal. *)
WriteString ("o^: "); WriteInt (o^, 0); WriteLn;
END TryMinOpaque.
The compiler should forbid access to the internals of the Opaque type.
$ gm2 --version
gm2 (GCC) 14.2.1 20250110 (Red Hat 14.2.1-7)
Copyright (C) 2024 Free Software Foundation, Inc.
This is free software; see the source for copying conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
This is on Fedora 41 with
$ uname -a
Linux atla 6.12.8-200.fc41.x86_64 #1 SMP PREEMPT_DYNAMIC Thu Jan 2 19:26:03
UTC 2025 x86_64 GNU/Linux
