From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Alan Mackenzie Newsgroups: gmane.emacs.devel Subject: Re: Circular records: how do I best handle them? (The new correct warning position branch now bootstraps in native compilation!) Date: Thu, 30 Dec 2021 16:49:52 +0000 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="27098"; mail-complaints-to="usenet@ciao.gmane.io" Cc: emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Thu Dec 30 17:51:34 2021 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1n2yeL-0006uD-CT for ged-emacs-devel@m.gmane-mx.org; Thu, 30 Dec 2021 17:51:33 +0100 Original-Received: from localhost ([::1]:45908 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1n2yeK-0001Ua-17 for ged-emacs-devel@m.gmane-mx.org; Thu, 30 Dec 2021 11:51:32 -0500 Original-Received: from eggs.gnu.org ([209.51.188.92]:53182) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n2yco-0000gY-Eg for emacs-devel@gnu.org; Thu, 30 Dec 2021 11:49:58 -0500 Original-Received: from colin.muc.de ([193.149.48.1]:40694 helo=mail.muc.de) by eggs.gnu.org with smtp (Exim 4.90_1) (envelope-from ) id 1n2ycl-0000yx-80 for emacs-devel@gnu.org; Thu, 30 Dec 2021 11:49:58 -0500 Original-Received: (qmail 27764 invoked by uid 3782); 30 Dec 2021 16:49:52 -0000 Original-Received: from acm.muc.de (p4fe1573b.dip0.t-ipconnect.de [79.225.87.59]) (using STARTTLS) by colin.muc.de (tmda-ofmipd) with ESMTP; Thu, 30 Dec 2021 17:49:52 +0100 Original-Received: (qmail 24056 invoked by uid 1000); 30 Dec 2021 16:49:52 -0000 Content-Disposition: inline In-Reply-To: X-Submission-Agent: TMDA/1.3.x (Ph3nix) X-Primary-Address: acm@muc.de Received-SPF: pass client-ip=193.149.48.1; envelope-from=acm@muc.de; helo=mail.muc.de X-Spam_score_int: 1 X-Spam_score: 0.1 X-Spam_bar: / X-Spam_report: (0.1 / 5.0 requ) PLING_QUERY=0.1, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:283667 Archived-At: Hello, Stefan. On Sun, Dec 26, 2021 at 15:35:35 -0500, Stefan Monnier wrote: > >> Hmm... circularity is quite normal in data structures, yes. > >> But presumably this is only applied to source code where circularity is > >> very rare. Could it be that you end up recursing in elements which > >> actually aren't part of the source code (and hence can't have > >> symbols-with-positions)? > > I honestly don't know at the moment. > I think it's worth the effort to try and track this down. Maybe we can > completely circumvent the problem. I don't think there are any such cases. I'll think it through fully, some time. > >> Also, I see in `byte-compile-strip-s-p-1` that you only look inside conses > >> and vectors. So I'm not sure what makes you say the recursion was in > >> records since records are similar to vectors but aren't `vectorp` so > >> AFAICT your code won't recurse into them. > > byte-compile-strip-s-p-1 has been enhanced to handle records, too, > > though I haven't committed that bit yet (along with quite a lot of other > > amendments, too). > Hmm... now that I think about it, you only generate > symbols-with-positions (symposes) when byte-compiling, right? Correct. > And you can restrict this to the case where we byte-compile into a file > (as opposed to the rare case where we just call `byte-compile`). I suppose this could be done, but there's no need. compile-defun isn't that rare a function, and we want the correct warning messages from it. > So the symposes can end up in 2 places: > - in the .elc file: no need to strip the pos here, just make sure the > symbols get printed without their position. The positions get stripped before the code is dumped to the .elc. > - elsewhere: that's the problematic part because this only occurs where > the source code gets stealthy passed elsewhere, e.g. when a macro > calls (put ARG1 'foo ARG2) during the macro expansion (rather than > returning that chunk of code in the expansion). This isn't a problem. If it is a compiled macro doing this, the positions will already be gone from the symbols. If it is from an uncompiled macro, XSYMBOL in Feval's subroutines does the Right Thing. > Here we don't have much control over where the symposes end up and I > don't think `byte-compile-strip-s-p` can help us (unless we call it > before passing the result to the macro, but I don't think that's > what we want to do). > So where/why do we need `byte-compile-strip-s-p`? It's now become macroexp-strip-symbol-position, so that it is always loaded early, and there is no need for a duplicate function in cl-macs.el any more. There didn't seem to be a better place to put it. It's used all over the place. In eval-when/and-compile, it is used before the evaluation. It is used before dumping the byte compiled code to the file.elc, and before passing this code to the native compiler. Several (?most) of the byte-compile-file-form-... functions use it. It's used in the newish keymap functions near the end of bytecomp.el, in byte-compile-annotate-call-tree, etc. Also in cl-define-compiler-macro, and internal-macro-expand-for-load. Additionally, also from Fput, to prevent symbols with positions getting into symbol property lists. > >> That's what we do elsewhere, yes, except that history taught us that > >> a hash-table is a better choice to avoid scalability problems. > >> Tho in your case you'd only need to keep the stack of objects inside of > >> which you're currently recursing, so maybe a list is good enough. > > I've tried the list approach (using memq to check for an already > > processed cons/vector/record. It fell flat on its face with > > lisp/leim/ja-dic/ja-dec.el, which has a list with over 60,000 strings > > in it. > Oh, right, we have to add to the list all the conses rather than only > the head conses, so you definitely want to use a hash-table. Yes, I have to do this. I am still debating whether just to do it (which might slow things down quite a bit), or to do it in a condition-case handler after the recursion has exceeded the 1,600 max-lisp-eval-depth. I'm inclined towards the latter at the moment. For other Lisp objects with a read syntax, such as char tables and decorated strings, I intend to amend the reader just to output plain symbols for them. > Stefan -- Alan Mackenzie (Nuremberg, Germany).