emacs-29 09bf4768360: Make c-emacs-features use the proper binding of parse-sexp-lookup-properties

[Stefan Monnier]

branch: emacs-29
commit 09bf4768360dd5b8928f90b0b1437f3f5ee43c41
Author: Alan Mackenzie <acm@muc.de>
Commit: Stefan Monnier <monnier@iro.umontreal.ca>

    Make c-emacs-features use the proper binding of parse-sexp-lookup-properties
    
    This is relevant for bug #58558, although it does not fix it.  Due to a 
wrong
    ordering of with-current-buffer and a let form, the function overwrote the
    global value of parse-sexp-lookup-properties and two other variables.
    
    * lisp/progmodes/cc-defs.el (c-emacs-features): Change the nesting of
    with-current-buffer and let so that the let bindings get used.
---
 lisp/progmodes/cc-defs.el | 151 ++++++++++++++++++++++------------------------
 1 file changed, 72 insertions(+), 79 deletions(-)

diff --git a/lisp/progmodes/cc-defs.el b/lisp/progmodes/cc-defs.el
index aa6f33e9cab..1d98b215525 100644
--- a/lisp/progmodes/cc-defs.el
+++ b/lisp/progmodes/cc-defs.el
@@ -2153,86 +2153,79 @@ non-nil, a caret is prepended to invert the set."
     ;; Record whether the `category' text property works.
     (if c-use-category (setq list (cons 'category-properties list)))
 
-    (let ((buf (generate-new-buffer " test"))
-         parse-sexp-lookup-properties
-         parse-sexp-ignore-comments
-         lookup-syntax-properties)     ; XEmacs
+    (let ((buf (generate-new-buffer " test")))
       (with-current-buffer buf
-       (set-syntax-table (make-syntax-table))
-
-       ;; For some reason we have to set some of these after the
-       ;; buffer has been made current.  (Specifically,
-       ;; `parse-sexp-ignore-comments' in Emacs 21.)
-       (setq parse-sexp-lookup-properties t
-             parse-sexp-ignore-comments t
-             lookup-syntax-properties t)
-
-       ;; Find out if the `syntax-table' text property works.
-       (modify-syntax-entry ?< ".")
-       (modify-syntax-entry ?> ".")
-       (insert "<()>")
-       (c-mark-<-as-paren (point-min))
-       (c-mark->-as-paren (+ 3 (point-min)))
-       (goto-char (point-min))
-       (c-forward-sexp)
-       (if (= (point) (+ 4 (point-min)))
-           (setq list (cons 'syntax-properties list))
-         (error (concat
-                 "CC Mode is incompatible with this version of Emacs - "
-                 "support for the `syntax-table' text property "
-                 "is required.")))
-
-       ;; Find out if "\\s!" (generic comment delimiters) work.
-       (c-safe
-         (modify-syntax-entry ?x "!")
-         (if (string-match "\\s!" "x")
-             (setq list (cons 'gen-comment-delim list))))
-
-       ;; Find out if "\\s|" (generic string delimiters) work.
-       (c-safe
-         (modify-syntax-entry ?x "|")
-         (if (string-match "\\s|" "x")
-             (setq list (cons 'gen-string-delim list))))
-
-       ;; See if POSIX char classes work.
-       (when (and (string-match "[[:alpha:]]" "a")
-                  ;; All versions of Emacs 21 so far haven't fixed
-                  ;; char classes in `skip-chars-forward' and
-                  ;; `skip-chars-backward'.
-                  (progn
-                    (delete-region (point-min) (point-max))
-                    (insert "foo123")
-                    (skip-chars-backward "[:alnum:]")
-                    (bobp))
-                  (= (skip-chars-forward "[:alpha:]") 3))
-         (setq list (cons 'posix-char-classes list)))
-
-       ;; See if `open-paren-in-column-0-is-defun-start' exists and
-       ;; isn't buggy (Emacs >= 21.4).
-       (when (boundp 'open-paren-in-column-0-is-defun-start)
-         (let ((open-paren-in-column-0-is-defun-start nil)
-               (parse-sexp-ignore-comments t))
-           (delete-region (point-min) (point-max))
-           (set-syntax-table (make-syntax-table))
-           (modify-syntax-entry ?\' "\"")
-           (cond
-            ;; XEmacs.  Afaik this is currently an Emacs-only
-            ;; feature, but it's good to be prepared.
-            ((memq '8-bit list)
-             (modify-syntax-entry ?/ ". 1456")
-             (modify-syntax-entry ?* ". 23"))
-            ;; Emacs
-            ((memq '1-bit list)
-             (modify-syntax-entry ?/ ". 124b")
-             (modify-syntax-entry ?* ". 23")))
-           (modify-syntax-entry ?\n "> b")
-           (insert "/* '\n   () */")
-           (backward-sexp)
-           (if (bobp)
-               (setq list (cons 'col-0-paren list)))))
-
-       (set-buffer-modified-p nil))
-      (kill-buffer buf))
+       (let ((parse-sexp-lookup-properties t)
+             (parse-sexp-ignore-comments t)
+             (lookup-syntax-properties t))
+         (set-syntax-table (make-syntax-table))
+
+         ;; Find out if the `syntax-table' text property works.
+         (modify-syntax-entry ?< ".")
+         (modify-syntax-entry ?> ".")
+         (insert "<()>")
+         (c-mark-<-as-paren (point-min))
+         (c-mark->-as-paren (+ 3 (point-min)))
+         (goto-char (point-min))
+         (c-forward-sexp)
+         (if (= (point) (+ 4 (point-min)))
+             (setq list (cons 'syntax-properties list))
+           (error (concat
+                   "CC Mode is incompatible with this version of Emacs - "
+                   "support for the `syntax-table' text property "
+                   "is required.")))
+
+         ;; Find out if "\\s!" (generic comment delimiters) work.
+         (c-safe
+           (modify-syntax-entry ?x "!")
+           (if (string-match "\\s!" "x")
+               (setq list (cons 'gen-comment-delim list))))
+
+         ;; Find out if "\\s|" (generic string delimiters) work.
+         (c-safe
+           (modify-syntax-entry ?x "|")
+           (if (string-match "\\s|" "x")
+               (setq list (cons 'gen-string-delim list))))
+
+         ;; See if POSIX char classes work.
+         (when (and (string-match "[[:alpha:]]" "a")
+                    ;; All versions of Emacs 21 so far haven't fixed
+                    ;; char classes in `skip-chars-forward' and
+                    ;; `skip-chars-backward'.
+                    (progn
+                      (delete-region (point-min) (point-max))
+                      (insert "foo123")
+                      (skip-chars-backward "[:alnum:]")
+                      (bobp))
+                    (= (skip-chars-forward "[:alpha:]") 3))
+           (setq list (cons 'posix-char-classes list)))
+
+         ;; See if `open-paren-in-column-0-is-defun-start' exists and
+         ;; isn't buggy (Emacs >= 21.4).
+         (when (boundp 'open-paren-in-column-0-is-defun-start)
+           (let ((open-paren-in-column-0-is-defun-start nil)
+                 (parse-sexp-ignore-comments t))
+             (delete-region (point-min) (point-max))
+             (set-syntax-table (make-syntax-table))
+             (modify-syntax-entry ?\' "\"")
+             (cond
+              ;; XEmacs.  Afaik this is currently an Emacs-only
+              ;; feature, but it's good to be prepared.
+              ((memq '8-bit list)
+               (modify-syntax-entry ?/ ". 1456")
+               (modify-syntax-entry ?* ". 23"))
+              ;; Emacs
+              ((memq '1-bit list)
+               (modify-syntax-entry ?/ ". 124b")
+               (modify-syntax-entry ?* ". 23")))
+             (modify-syntax-entry ?\n "> b")
+             (insert "/* '\n   () */")
+             (backward-sexp)
+             (if (bobp)
+                 (setq list (cons 'col-0-paren list)))))
+
+         (set-buffer-modified-p nil))
+       (kill-buffer buf)))
 
     ;; Check how many elements `parse-partial-sexp' returns.
     (let ((ppss-size (or (c-safe (length