Package: cc-mode;
Reported by: Arsen Arsenović <arsen <at> aarsen.me>
Date: Fri, 3 Nov 2023 10:24:02 UTC
Severity: normal
Done: Alan Mackenzie <acm <at> muc.de>
Bug is archived. No further changes may be made.
Message #26 received at 66911 <at> debbugs.gnu.org (full text, mbox):
From: Alan Mackenzie <acm <at> muc.de> To: Arsen Arsenović <arsen <at> aarsen.me> Cc: acm <at> muc.de, 66911 <at> debbugs.gnu.org Subject: Re: bug#66911: CC Mode 5.35.2 (C++//l); Noise macro being taken as anchor to class-open Date: Fri, 17 Nov 2023 12:09:28 +0000
Hello, Arsen.
On Thu, Nov 16, 2023 at 21:29:29 +0100, Arsen Arsenović wrote:
> Hi Alan,
> Thanks for working on this.
> Alan Mackenzie <acm <at> muc.de> writes:
[ .... ]
> > That was a mistake - the second anchor point is needed on class-open
> > lines, not topmost-intro-cont ones.
> > I've coded up this patch, which I include below. Actually, only the last
> > two smallish hunks of the patch are new, the rest is what you've seen
> > before, so it will be necessary to start from a clean copy of
> > cc-engine.el again.
> > The syntactical context of the HERE line (the opening brace of that
> > class) is now something like:
> > ((class-open 76 107))
> > , where 76 is the position of the template keyword and 107 that of the
> > class keyword. When there's no template, both of these anchor points are
> > the same. Actually, that's not quite accurate: the 107 is the point
> > after the indentation of the line that class is on; it just seemed better
> > that way.
> This behavior seems reasonable to me at a glance and at a test. I like
> the idea :-)
[ .... ]
> > So, again, please let me know how you get on with this patch. Is the
> > extra anchor point sufficient to write an alignment function to get the
> > indentation you want?
> The following did work nicely (after I made c-langelem-2nd-col, by
> copying and altering c-langelem-col as is obvious). I'm not sure if it
> is idiomatic or the cleanest solution, though (plus, my Elisp-fu is
> poor).
> --8<---------------cut here---------------start------------->8---
> (defun glibcxx-style/line-up-struct (sym-form)
> "Lines up a class-open with its prior struct line"
> (if (not (eq 'class-open (c-langelem-sym sym-form)))
> nil
> (let ((col (c-langelem-2nd-col c-syntactic-element t)))
> (if col
> (vector col)
> nil))))
> --8<---------------cut here---------------end--------------->8---
> ... however, I noticed that class-close still anchors on the template
> that precedes it, and seems to not have a 2nd-pos to play with, so the
> above line-up fn, when set on class-open, produces:
> --8<---------------cut here---------------start------------->8---
> template<typename foo>
> struct f
> {
> };
> --8<---------------cut here---------------end--------------->8---
Yes. I should have noticed this myself. :-(
> ... so, we're getting quite close!
So, please try out the new patch (below) which supplies the second anchor
point to class-close too. The patch applies cleanly to the Emacs master
branch. Again, please start off with a clean cc-engine.el before
applying the new patch, not the version with the previous patch applied.
[ .... ]
diff -r 2760aada61fa cc-engine.el
--- a/cc-engine.el Sun Oct 15 10:44:22 2023 +0000
+++ b/cc-engine.el Fri Nov 17 11:49:55 2023 +0000
@@ -12633,31 +12633,27 @@
(let ((open-brace (point)) kwd-start first-specifier-pos)
(c-syntactic-skip-backward c-block-prefix-charset limit t)
- (when (and c-recognize-<>-arglists
- (eq (char-before) ?>))
- ;; Could be at the end of a template arglist.
- (let ((c-parse-and-markup-<>-arglists t))
- (while (and
- (c-backward-<>-arglist nil limit)
- (progn
- (c-syntactic-skip-backward c-block-prefix-charset limit t)
- (eq (char-before) ?>))))))
-
- ;; Skip back over noise clauses.
- (while (and
- c-opt-cpp-prefix
- (eq (char-before) ?\))
- (let ((after-paren (point)))
- (if (and (c-go-list-backward)
- (progn (c-backward-syntactic-ws)
- (c-simple-skip-symbol-backward))
- (or (looking-at c-paren-nontype-key)
- (looking-at c-noise-macro-with-parens-name-re)))
- (progn
- (c-syntactic-skip-backward c-block-prefix-charset limit t)
- t)
- (goto-char after-paren)
- nil))))
+ (while
+ (or
+ ;; Could be after a template arglist....
+ (and c-recognize-<>-arglists
+ (eq (char-before) ?>)
+ (let ((c-parse-and-markup-<>-arglists t))
+ (c-backward-<>-arglist nil limit)))
+ ;; .... or after a noise clause with parens.
+ (and c-opt-cpp-prefix
+ (let ((after-paren (point)))
+ (if (eq (char-before) ?\))
+ (and
+ (c-go-list-backward)
+ (eq (char-after) ?\()
+ (progn (c-backward-syntactic-ws)
+ (c-simple-skip-symbol-backward))
+ (or (looking-at c-paren-nontype-key) ; e.g. __attribute__
+ (looking-at c-noise-macro-with-parens-name-re)))
+ (goto-char after-paren)
+ nil))))
+ (c-syntactic-skip-backward c-block-prefix-charset limit t))
;; Note: Can't get bogus hits inside template arglists below since they
;; have gotten paren syntax above.
@@ -12667,10 +12663,18 @@
;; The `c-decl-block-key' search continues from there since
;; we know it can't match earlier.
(if goto-start
- (when (c-syntactic-re-search-forward c-symbol-start
- open-brace t t)
- (goto-char (setq first-specifier-pos (match-beginning 0)))
- t)
+ (progn
+ (while
+ (and
+ (c-syntactic-re-search-forward c-symbol-start
+ open-brace t t)
+ (goto-char (match-beginning 0))
+ (if (or (looking-at c-noise-macro-name-re)
+ (looking-at c-noise-macro-with-parens-name-re))
+ (c-forward-noise-clause)
+ (setq first-specifier-pos (match-beginning 0))
+ nil)))
+ first-specifier-pos)
t)
(cond
@@ -12739,34 +12743,39 @@
(goto-char first-specifier-pos)
(while (< (point) kwd-start)
- (if (looking-at c-symbol-key)
- ;; Accept any plain symbol token on the ground that
- ;; it's a specifier masked through a macro (just
- ;; like `c-forward-decl-or-cast-1' skip forward over
- ;; such tokens).
- ;;
- ;; Could be more restrictive wrt invalid keywords,
- ;; but that'd only occur in invalid code so there's
- ;; no use spending effort on it.
- (let ((end (match-end 0))
- (kwd-sym (c-keyword-sym (match-string 0))))
- (unless
- (and kwd-sym
- ;; Moving over a protection kwd and the following
- ;; ":" (in C++ Mode) to the next token could take
- ;; us all the way up to `kwd-start', leaving us
- ;; no chance to update `first-specifier-pos'.
- (not (c-keyword-member kwd-sym 'c-protection-kwds))
- (c-forward-keyword-clause 0))
- (goto-char end)
- (c-forward-syntactic-ws)))
-
+ (cond
+ ((or (looking-at c-noise-macro-name-re)
+ (looking-at c-noise-macro-with-parens-name-re))
+ (c-forward-noise-clause))
+ ((looking-at c-symbol-key)
+ ;; Accept any plain symbol token on the ground that
+ ;; it's a specifier masked through a macro (just
+ ;; like `c-forward-decl-or-cast-1' skips forward over
+ ;; such tokens).
+ ;;
+ ;; Could be more restrictive wrt invalid keywords,
+ ;; but that'd only occur in invalid code so there's
+ ;; no use spending effort on it.
+ (let ((end (match-end 0))
+ (kwd-sym (c-keyword-sym (match-string 0))))
+ (unless
+ (and kwd-sym
+ ;; Moving over a protection kwd and the following
+ ;; ":" (in C++ Mode) to the next token could take
+ ;; us all the way up to `kwd-start', leaving us
+ ;; no chance to update `first-specifier-pos'.
+ (not (c-keyword-member kwd-sym 'c-protection-kwds))
+ (c-forward-keyword-clause 0))
+ (goto-char end)
+ (c-forward-syntactic-ws))))
+
+ ((c-syntactic-re-search-forward c-symbol-start
+ kwd-start 'move t)
;; Can't parse a declaration preamble and is still
;; before `kwd-start'. That means `first-specifier-pos'
;; was in some earlier construct. Search again.
- (if (c-syntactic-re-search-forward c-symbol-start
- kwd-start 'move t)
- (goto-char (setq first-specifier-pos (match-beginning 0)))
+ (goto-char (setq first-specifier-pos (match-beginning 0))))
+ (t
;; Got no preamble before the block declaration keyword.
(setq first-specifier-pos kwd-start))))
@@ -14181,7 +14190,8 @@
(defun c-add-class-syntax (symbol
containing-decl-open
containing-decl-start
- containing-decl-kwd)
+ containing-decl-kwd
+ &rest args)
;; The inclass and class-close syntactic symbols are added in
;; several places and some work is needed to fix everything.
;; Therefore it's collected here.
@@ -14196,7 +14206,7 @@
;; Ought to use `c-add-stmt-syntax' instead of backing up to boi
;; here, but we have to do like this for compatibility.
(back-to-indentation)
- (c-add-syntax symbol (point))
+ (apply #'c-add-syntax symbol (point) args)
(if (and (c-keyword-member containing-decl-kwd
'c-inexpr-class-kwds)
(/= containing-decl-start (c-point 'boi containing-decl-start)))
@@ -14230,9 +14240,10 @@
;; CASE B.1: class-open
((save-excursion
(and (eq (char-after) ?{)
- (c-looking-at-decl-block t)
+ (setq placeholder (c-looking-at-decl-block t))
(setq beg-of-same-or-containing-stmt (point))))
- (c-add-syntax 'class-open beg-of-same-or-containing-stmt))
+ (c-add-syntax 'class-open beg-of-same-or-containing-stmt
+ (c-point 'boi placeholder)))
;; CASE B.2: brace-list-open
((or (consp special-brace-list)
@@ -14727,7 +14738,10 @@
'lambda-intro-cont)))
(goto-char (cdr placeholder))
(back-to-indentation)
- (c-add-stmt-syntax tmpsymbol nil t
+ (c-add-stmt-syntax tmpsymbol
+ (and (eq tmpsymbol 'class-open)
+ (list (point)))
+ t
(c-most-enclosing-brace state-cache (point))
paren-state)
(unless (eq (point) (cdr placeholder))
@@ -14770,9 +14784,10 @@
(goto-char indent-point)
(skip-chars-forward " \t")
(and (eq (char-after) ?{)
- (c-looking-at-decl-block t)
+ (setq tmp-pos (c-looking-at-decl-block t))
(setq placeholder (point))))
- (c-add-syntax 'class-open placeholder))
+ (c-add-syntax 'class-open placeholder
+ (c-point 'boi tmp-pos)))
;; CASE 5A.3: brace list open
((save-excursion
@@ -15170,10 +15185,14 @@
((and containing-sexp
(eq char-after-ip ?})
(eq containing-decl-open containing-sexp))
+ (save-excursion
+ (goto-char containing-decl-open)
+ (setq tmp-pos (c-looking-at-decl-block t)))
(c-add-class-syntax 'class-close
containing-decl-open
containing-decl-start
- containing-decl-kwd))
+ containing-decl-kwd
+ (c-point 'boi tmp-pos)))
;; CASE 5H: we could be looking at subsequent knr-argdecls
((and c-recognize-knr-p
> --
> Arsen Arsenović
--
Alan Mackenzie (Nuremberg, Germany).
GNU bug tracking system
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1997,2003 nCipher Corporation Ltd,
1994-97 Ian Jackson.