>From b19dbd60af4282ab8dcd1512f6910da6671d8a4a Mon Sep 17 00:00:00 2001 From: Noam Postavsky Date: Sat, 10 Mar 2018 18:12:55 -0500 Subject: [PATCH v3 2/2] Improve errors & warnings due to fancy quoted vars (Bug#32939) Add some hints to the message for byte compiler free & unused variable warnings, and 'void-variable' errors where the variable has confusable quote characters in it. * lisp/help.el (uni-confusables), uni-confusables-regexp): New constants. (help-command-error-confusable-suggestions): New function, added to `command-error-function'. (help-uni-confusable-suggestions): New function. * lisp/emacs-lisp/bytecomp.el (byte-compile-variable-ref): * lisp/emacs-lisp/cconv.el (cconv--analyze-use): Use it. * lisp/emacs-lisp/lisp-mode.el (lisp--match-confusable-symbol-character): New function. (lisp-fdefs): Use it to fontify confusable characters with font-lock-warning-face when they occur in symbol names. * doc/lispref/modes.texi (Faces for Font Lock): * doc/lispref/objects.texi (Basic Char Syntax): Recommend backslash escaping of confusable characters, and mention new fontification. * etc/NEWS: Announce the new fontification behavior. * test/lisp/emacs-lisp/lisp-mode-tests.el (lisp-fontify-confusables): New test. --- doc/lispref/modes.texi | 3 +- doc/lispref/objects.texi | 7 ++++- etc/NEWS | 4 +++ lisp/emacs-lisp/bytecomp.el | 10 +++++-- lisp/emacs-lisp/cconv.el | 6 ++-- lisp/emacs-lisp/lisp-mode.el | 18 +++++++++++- lisp/help.el | 49 +++++++++++++++++++++++++++++++++ test/lisp/emacs-lisp/lisp-mode-tests.el | 24 ++++++++++++++++ 8 files changed, 114 insertions(+), 7 deletions(-) diff --git a/doc/lispref/modes.texi b/doc/lispref/modes.texi index 49b7e1ea3f..243e535988 100644 --- a/doc/lispref/modes.texi +++ b/doc/lispref/modes.texi @@ -3190,7 +3190,8 @@ Faces for Font Lock @table @code @item font-lock-warning-face @vindex font-lock-warning-face -for a construct that is peculiar, or that greatly changes the meaning of +for a construct that is peculiar (e.g., an unescaped confusable quote +in an Emacs Lisp symbol like @samp{‘foo}), or that greatly changes the meaning of other text, like @samp{;;;###autoload} in Emacs Lisp and @samp{#error} in C. diff --git a/doc/lispref/objects.texi b/doc/lispref/objects.texi index a0940032ee..f82ee7c49a 100644 --- a/doc/lispref/objects.texi +++ b/doc/lispref/objects.texi @@ -347,7 +347,12 @@ Basic Char Syntax characters. However, you must add a backslash before any of the characters @samp{()[]\;"}, and you should add a backslash before any of the characters @samp{|'`#.,} to avoid confusing the Emacs commands -for editing Lisp code. You can also add a backslash before whitespace +for editing Lisp code. You should also add a backslash before Unicode +characters which resemble the previously mentioned @acronym{ASCII} +ones, to avoid confusing people reading your code. Emacs will +highlight some non-escaped commonly confused characters such as +@samp{‘} to encourage this. + You can also add a backslash before whitespace characters such as space, tab, newline and formfeed. However, it is cleaner to use one of the easily readable escape sequences, such as @samp{\t} or @samp{\s}, instead of an actual whitespace character such diff --git a/etc/NEWS b/etc/NEWS index 3530e04467..395169253d 100644 --- a/etc/NEWS +++ b/etc/NEWS @@ -1089,6 +1089,10 @@ and if the new behavior breaks your code please email 32252@debbugs.gnu.org. Because %o and %x can now format signed integers, they now support the + and space flags. +** In Emacs Lisp mode, symbols with confusable quotes are highlighted. +For example, the first character in '‘foo' would be highlighted in +'font-lock-warning-face'. + +++ ** Omitting variables after '&optional' and '&rest' is now allowed. For example (defun foo (&optional)) is no longer an error. This is diff --git a/lisp/emacs-lisp/bytecomp.el b/lisp/emacs-lisp/bytecomp.el index 8b67e1007d..31d589ab02 100644 --- a/lisp/emacs-lisp/bytecomp.el +++ b/lisp/emacs-lisp/bytecomp.el @@ -3407,7 +3407,10 @@ byte-compile-variable-ref (boundp var) (memq var byte-compile-bound-variables) (memq var byte-compile-free-references)) - (byte-compile-warn "reference to free variable `%S'" var) + (let* ((varname (prin1-to-string var)) + (suggestions (help-uni-confusable-suggestions varname))) + (byte-compile-warn "reference to free variable `%s'%s" varname + (if suggestions (concat "\n " suggestions) ""))) (push var byte-compile-free-references)) (byte-compile-dynamic-variable-op 'byte-varref var)))) @@ -3423,7 +3426,10 @@ byte-compile-variable-set (boundp var) (memq var byte-compile-bound-variables) (memq var byte-compile-free-assignments)) - (byte-compile-warn "assignment to free variable `%s'" var) + (let* ((varname (prin1-to-string var)) + (suggestions (help-uni-confusable-suggestions varname))) + (byte-compile-warn "assignment to free variable `%s'%s" varname + (if suggestions (concat "\n " suggestions) ""))) (push var byte-compile-free-assignments)) (byte-compile-dynamic-variable-op 'byte-varset var)))) diff --git a/lisp/emacs-lisp/cconv.el b/lisp/emacs-lisp/cconv.el index 010026b416..b62c69868b 100644 --- a/lisp/emacs-lisp/cconv.el +++ b/lisp/emacs-lisp/cconv.el @@ -591,8 +591,10 @@ cconv--analyze-use (eq ?_ (aref (symbol-name var) 0)) ;; As a special exception, ignore "ignore". (eq var 'ignored)) - (byte-compile-warn "Unused lexical %s `%S'" - varkind var))) + (let ((suggestions (help-uni-confusable-suggestions (symbol-name var)))) + (byte-compile-warn "Unused lexical %s `%S'%s" + varkind var + (if suggestions (concat "\n " suggestions) ""))))) ;; If it's unused, there's no point converting it into a cons-cell, even if ;; it's captured and mutated. (`(,binder ,_ t t ,_) diff --git a/lisp/emacs-lisp/lisp-mode.el b/lisp/emacs-lisp/lisp-mode.el index f31b4d4dd2..619d525309 100644 --- a/lisp/emacs-lisp/lisp-mode.el +++ b/lisp/emacs-lisp/lisp-mode.el @@ -280,6 +280,19 @@ elisp--font-lock-backslash `(face ,font-lock-warning-face help-echo "This \\ has no effect")))) +(defun lisp--match-confusable-symbol-character (limit) + ;; Match a confusable character within a Lisp symbol. + (catch 'matched + (while t + (if (re-search-forward uni-confusables-regexp limit t) + ;; Skip confusables which are backslash escaped, or inside + ;; strings or comments. + (save-match-data + (unless (or (eq (char-before (match-beginning 0)) ?\\) + (nth 8 (syntax-ppss))) + (throw 'matched t))) + (throw 'matched nil))))) + (let-when-compile ((lisp-fdefs '("defmacro" "defun")) (lisp-vdefs '("defvar")) @@ -463,7 +476,10 @@ elisp--font-lock-backslash (3 'font-lock-regexp-grouping-construct prepend)) (lisp--match-hidden-arg (0 '(face font-lock-warning-face - help-echo "Hidden behind deeper element; move to another line?"))) + help-echo "Hidden behind deeper element; move to another line?"))) + (lisp--match-confusable-symbol-character + 0 '(face font-lock-warning-face + help-echo "Confusable character")) )) "Gaudy level highlighting for Emacs Lisp mode.") diff --git a/lisp/help.el b/lisp/help.el index 6e06fc9e1c..2cc28fca24 100644 --- a/lisp/help.el +++ b/lisp/help.el @@ -1489,6 +1489,55 @@ help--make-usage-docstring (help--docstring-quote (format "%S" (help--make-usage fn arglist))))) + +;; Just some quote-like characters for now. TODO: generate this stuff +;; from official Unicode data. +(defconst uni-confusables + '((#x2018 . "'") ;; LEFT SINGLE QUOTATION MARK + (#x2019 . "'") ;; RIGHT SINGLE QUOTATION MARK + (#x201B . "'") ;; SINGLE HIGH-REVERSED-9 QUOTATION MARK + (#x201C . "\"") ;; LEFT DOUBLE QUOTATION MARK + (#x201D . "\"") ;; RIGHT DOUBLE QUOTATION MARK + (#x201F . "\"") ;; DOUBLE HIGH-REVERSED-9 QUOTATION MARK + (#x301E . "\"") ;; DOUBLE PRIME QUOTATION MARK + (#xFF02 . "'") ;; FULLWIDTH QUOTATION MARK + (#xFF07 . "'") ;; FULLWIDTH APOSTROPHE + )) + +(defconst uni-confusables-regexp + (concat "[" (mapcar #'car uni-confusables) "]")) + +(defun help-uni-confusable-suggestions (string) + "Return a message describing confusables in STRING." + (let ((i 0) + (confusables nil)) + (while (setq i (string-match uni-confusables-regexp string i)) + (let ((replacement (alist-get (aref string i) uni-confusables))) + (push (aref string i) confusables) + (setq string (replace-match replacement t t string)) + (setq i (+ i (length replacement))))) + (when confusables + (format-message + (if (> (length confusables) 1) + "Found confusable characters: %s; perhaps you meant: `%s'?" + "Found confusable character: %s, perhaps you meant: `%s'?") + (mapconcat (lambda (c) (format-message "`%c'" c)) + confusables ", ") + string)))) + +(defun help-command-error-confusable-suggestions (data _context _signal) + (pcase data + (`(void-variable ,var) + (let ((suggestions (help-uni-confusable-suggestions + (symbol-name var)))) + (when suggestions + (princ (concat "\n " suggestions) t)))) + (_ nil))) + +(add-function :after command-error-function + #'help-command-error-confusable-suggestions) + + (provide 'help) ;;; help.el ends here diff --git a/test/lisp/emacs-lisp/lisp-mode-tests.el b/test/lisp/emacs-lisp/lisp-mode-tests.el index 30f606d381..8339591740 100644 --- a/test/lisp/emacs-lisp/lisp-mode-tests.el +++ b/test/lisp/emacs-lisp/lisp-mode-tests.el @@ -20,6 +20,10 @@ (require 'ert) (require 'cl-lib) (require 'lisp-mode) +(require 'faceup) + + +;;; Indentation (defconst lisp-mode-tests--correctly-indented-sexp "\ \(a @@ -256,7 +260,27 @@ lisp-mode-tests--correctly-indented-sexp (lisp-indent-line) (should (equal (buffer-string) "prompt> foo")))) + +;;; Fontification +(ert-deftest lisp-fontify-confusables () + "Unescaped 'smart quotes' should be fontified in `font-lock-warning-face'." + (with-temp-buffer + (dolist (ch + '(#x2018 ;; LEFT SINGLE QUOTATION MARK + #x2019 ;; RIGHT SINGLE QUOTATION MARK + #x201B ;; SINGLE HIGH-REVERSED-9 QUOTATION MARK + #x201C ;; LEFT DOUBLE QUOTATION MARK + #x201D ;; RIGHT DOUBLE QUOTATION MARK + #x201F ;; DOUBLE HIGH-REVERSED-9 QUOTATION MARK + #x301E ;; DOUBLE PRIME QUOTATION MARK + #xFF02 ;; FULLWIDTH QUOTATION MARK + #xFF07 ;; FULLWIDTH APOSTROPHE + )) + (insert (format "«w:%c»foo \\%cfoo\n" ch ch))) + (let ((faceup (buffer-string))) + (faceup-clean-buffer) + (should (faceup-test-font-lock-buffer 'emacs-lisp-mode faceup))))) (provide 'lisp-mode-tests) ;;; lisp-mode-tests.el ends here -- 2.11.0