digitalmars.D.bugs - [Issue 2544] New: implicit const casting rules allow violations of const-safety
- d-bugmail puremagic.com (36/36) Dec 27 2008 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (13/13) Jan 01 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (13/13) Jan 02 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (9/9) Feb 18 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (10/10) Dec 17 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (16/16) Dec 17 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (8/16) Dec 17 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (16/19) Dec 17 2009 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (8/8) Mar 16 2010 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (8/9) Apr 14 2010 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (10/10) Apr 14 2010 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (12/12) Jul 20 2010 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (7/7) Nov 18 2010 http://d.puremagic.com/issues/show_bug.cgi?id=2544
- d-bugmail puremagic.com (15/15) Jun 15 2011 http://d.puremagic.com/issues/show_bug.cgi?id=2544
http://d.puremagic.com/issues/show_bug.cgi?id=2544 Summary: implicit const casting rules allow violations of const- safety Product: D Version: 2.022 Platform: PC OS/Version: Linux Status: NEW Keywords: spec Severity: major Priority: P2 Component: DMD AssignedTo: bugzilla digitalmars.com ReportedBy: lat7h virginia.edu The const system allows const views of mutable data; however, when used with enough levels of indirection, accidental mutable access of const data is also possible. The smallest example I have found is ---- const(real)[] constants = [3.14159265358979323844L, 2.71828182845904523536L]; real[][][] unconsted = [[[]]]; // create mutable data const(real)[][][] unsafe = unconsted; // and a partially-constant view of it unsafe[0] = [constants]; // place const data in the const view unconsted[0][0][0] = 3.14L; // simplify pi using the mutable view ---- This is obviously contrived, but several of these layers of indirection can be achieved (less succinctly but more commonly) using ref parameters to methods instead. I think that it suffices to require most intermediate levels of const-ness to be illegal; you can either have the original const-ness or a more-const formal with at most (I think) 2 levels of mutable indirection remaining: const(T[])[][] assigned from T[][][] is OK, const(T)[][][] assigned from T[][][] is not OK. I have not been able to prove two levels is safe, but I have also not been able to construct a counterexample. --
Dec 27 2008
http://d.puremagic.com/issues/show_bug.cgi?id=2544 I included an unnecessary level of indirection before. A simpler example: ---- const(int)[] answers = [42]; // create const data int[][] unconsted = [[]]; // create mutable data const(int)[][] unsafe = unconsted; // and a partially-constant view of it unsafe[0] = answers; // place const data in the const view unconsted[0][0] = 43; // change const data ---- Thus, while "const(T)[] = T[]" is safe, "const(T)[][] = T[][]" is not; only a single level of implicit indirection in the cast preserves constness. --
Jan 01 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2544 smjg iname.com changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |smjg iname.com I've thought quite a bit about this and come up with what seems to be a solution, which also deals with another problem that's been around for years. I've posted it on the newsgroup, as it's rather long for here. "Possible D2 solution to the upcasting array problem, and a related problem with const and nested arrays" http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D&article_id=81566 --
Jan 02 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2544 maxmo pochta.ru changed: What |Removed |Added ---------------------------------------------------------------------------- Status|NEW |RESOLVED Resolution| |DUPLICATE *** This bug has been marked as a duplicate of 2095 *** --
Feb 18 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2544 Stewart Gordon <smjg iname.com> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bugzilla digitalmars.com *** Issue 3621 has been marked as a duplicate of this issue. *** -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Dec 17 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2544 Steven Schveighoffer <schveiguy yahoo.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|RESOLVED |REOPENED CC| |schveiguy yahoo.com Resolution|DUPLICATE | 05:11:24 PST --- I'm going to reopen this. Although it is technically a subset of bug 2095, it is not a duplicate. It is possible to fix this bug without fixing 2095. It appears that a fix was inserted for 3621, repeated here for consistency: http://www.dsource.org/projects/dmd/changeset/299 When the compiler is released with this fix, then this bug can be closed. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Dec 17 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2544I'm going to reopen this. Although it is technically a subset of bug 2095, it is not a duplicate. It is possible to fix this bug without fixing 2095. It appears that a fix was inserted for 3621, repeated here for consistency: http://www.dsource.org/projects/dmd/changeset/299 When the compiler is released with this fix, then this bug can be closed.Does this change cover all cases discussed in the thread linked to in comment 2? -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Dec 17 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2544 05:31:50 PST ---Does this change cover all cases discussed in the thread linked to in comment 2?From looking at the code changes, it does not fix casts from a derived class array to a base class array. However, that issue is captured in bug 2095. I don't think this means 2095 is not an important bug to fix, but it might be that this bug is *really* simple to fix, and 2095 is not (Walter would know better). I'd rather have this part of it fixed than neither part fixed. In any case, the example in comment 1 and the original description should theoretically be fixed by the change, so we can at least close *this* bug. I agree that something needs to be done about casting a derived class array to a base class array, and it seems like the solution proposed in the thread would work. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Dec 17 2009
http://d.puremagic.com/issues/show_bug.cgi?id=2544 20:19:39 PDT --- It appears that the offending code still compiles in dmd 2.041. I can't remember why I thought the given changeset should fix the problem, maybe it was fixed and then regressed. In any case, it's still broken. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Mar 16 2010
http://d.puremagic.com/issues/show_bug.cgi?id=2544 10:36:19 PDT ---Although it is technically a subset of bug 2095To be precise, it's theoretically a subset of 2095, but technically they are different :) -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Apr 14 2010
http://d.puremagic.com/issues/show_bug.cgi?id=2544 Stewart Gordon <smjg iname.com> changed: What |Removed |Added ---------------------------------------------------------------------------- OS/Version|Linux |All Since when has this issue been Linux-specific? -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Apr 14 2010
http://d.puremagic.com/issues/show_bug.cgi?id=2544 Leandro Lucarella <llucax gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Version|D1 & D2 |2.022 PDT --- I'm sorry about the last version change, I accidentally changed it thinking I was editing bug 3463 instead (I hate bugzilla for automatically moving to the next bug report when committing changes). -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jul 20 2010
http://d.puremagic.com/issues/show_bug.cgi?id=2544 12:15:53 PST --- Seems to be a regression, since according to bug 2056, this code didn't compile in dmd 2.013. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Nov 18 2010
http://d.puremagic.com/issues/show_bug.cgi?id=2544 yebblies <yebblies gmail.com> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|REOPENED |RESOLVED CC| |yebblies gmail.com Resolution| |DUPLICATE As far as I can tell, all of these cases are fixed by my patch to 4251. It uses references as the highest indirection instead of arrays, but exposes the same bug. *** This issue has been marked as a duplicate of issue 4251 *** -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 15 2011