Support curved quotes in doc strings

Emacs's traditional doc string style has been to quote symbols
`like this'.  This worked well on now-obsolete terminals where
` and ' were symmetric quotes, but nowadays curved quotes
‘like this’ look better.  Support quoting the new way too.
(Bug#20385)
* doc/lispref/tips.texi (Documentation Tips): Symbols can be quoted
‘like-this’ as well as `like-this'.
* etc/NEWS: Mention this.
* lisp/cedet/mode-local.el (overload-docstring-extension)
(mode-local-print-binding, mode-local-describe-bindings-2):
* lisp/cus-theme.el (describe-theme-1):
* lisp/descr-text.el (describe-text-properties-1, describe-char):
* lisp/emacs-lisp/checkdoc.el (checkdoc-this-string-valid-engine):
* lisp/emacs-lisp/cl-generic.el (cl--generic-describe):
* lisp/emacs-lisp/eieio-opt.el (eieio-help-class)
(eieio-help-constructor):
* lisp/emacs-lisp/package.el (describe-package-1):
* lisp/faces.el (describe-face):
* lisp/help-fns.el (help-fns--key-bindings)
(help-fns--compiler-macro, help-fns--parent-mode, help-fns--obsolete):
(help-fns--interactive-only, describe-function-1):
(describe-variable):
* lisp/help.el (describe-mode):
* lisp/international/mule-cmds.el (describe-input-method)
(describe-language-environment):
* lisp/international/mule-diag.el (describe-character-set)
(print-coding-system-briefly, list-input-methods)
(list-input-methods-1):
Insert curved quotes rather than grave accent and apostrophe.
* lisp/cedet/srecode/texi.el (srecode-texi-texify-docstring):
* lisp/emacs-lisp/checkdoc.el (checkdoc-this-string-valid-engine)
(checkdoc-proper-noun-region-engine):
* lisp/emacs-lisp/lisp-mode.el (lisp-el-font-lock-keywords-2)
(lisp-cl-font-lock-keywords-2):
* lisp/finder.el (finder-font-lock-keywords):
* lisp/gnus/gnus-art.el (gnus-button-alist):
* lisp/help-fns.el (help-do-arg-highlight)
(describe-function-1, describe-variable):
* lisp/help-mode.el (help-xref-symbol-regexp)
(help-xref-info-regexp, help-xref-url-regexp):
* lisp/help.el (describe-mode):
* lisp/international/mule-cmds.el (help-xref-mule-regexp-template):
* lisp/wid-edit.el (widget-documentation-link-regexp):
Parse symbols quoted ‘like-this’ as well as `like-this'.
* lisp/progmodes/elisp-mode.el (emacs-lisp-mode):
Add "‘" and "’" to electric-pair-text-pairs.
(elisp--form-quoted-p): Also allow "‘" as a quoting char.
(elisp-completion-at-point, elisp--preceding-sexp):
Also treat "‘" and "’" as quoting chars.

1 files changed, 20 insertions, 15 deletions

diff --git a/doc/lispref/tips.texi b/doc/lispref/tips.texi
index cc1f0e42750..798b6700aac 100644
--- a/doc/lispref/tips.texi
+++ b/doc/lispref/tips.texi
@@ -658,17 +658,22 @@ starting double-quote is not part of the string!
 @anchor{Docstring hyperlinks}
 @item
 When a documentation string refers to a Lisp symbol, write it as it
-would be printed (which usually means in lower case), with a grave
-accent @samp{`} before and apostrophe @samp{'} after it.  There are
+would be printed (which usually means in lower case), surrounding
+it with curved single quotes (@samp{‘} and @samp{’}).  There are
 two exceptions: write @code{t} and @code{nil} without surrounding
-punctuation.  For example: @samp{CODE can be `lambda', nil, or t.}
-(In this manual, we use a different convention, with single-quotes
-around symbols.)
+punctuation.  For example: @samp{CODE can be ‘lambda’, nil, or t.}
+
+Documentation strings can also use an older single-quoting convention,
+which quotes symbols with grave accent @samp{`} and apostrophe
+@samp{'}: @samp{`like-this'} rather than @samp{‘like-this’}.  This
+older convention was designed for now-obsolete displays in which grave
+accent and apostrophe were mirror images.  Documentation in this older
+convention is converted to the standard convention when it is copied
+into a help buffer.  @xref{Keys in Documentation}.
 
 @cindex hyperlinks in documentation strings
 Help mode automatically creates a hyperlink when a documentation string
-uses a symbol name between grave accent and apostrophe, if the symbol
-has either a
+uses a single-quoted symbol name, if the symbol has either a
 function or a variable definition.  You do not need to do anything
 special to make use of this feature.  However, when a symbol has both a
 function definition and a variable definition, and you want to refer to
@@ -678,7 +683,7 @@ immediately before the symbol name.  (Case makes no difference in
 recognizing these indicator words.)  For example, if you write
 
 @example
-This function sets the variable `buffer-file-name'.
+This function sets the variable ‘buffer-file-name’.
 @end example
 
 @noindent
@@ -691,7 +696,7 @@ you can write the words @samp{symbol} or @samp{program} before the
 symbol name to prevent making any hyperlink.  For example,
 
 @example
-If the argument KIND-OF-RESULT is the symbol `list',
+If the argument KIND-OF-RESULT is the symbol ‘list’,
 this function returns a list of all the objects
 that satisfy the criterion.
 @end example
@@ -710,21 +715,21 @@ followed by the word @samp{face}.  In that case, only the face
 documentation will be shown, even if the symbol is also defined as a
 variable or as a function.
 
-To make a hyperlink to Info documentation, write the name of the Info
-node (or anchor) between grave accent and apostrophe, preceded by
+To make a hyperlink to Info documentation, write the single-quoted
+name of the Info node (or anchor), preceded by
 @samp{info node}, @samp{Info node}, @samp{info anchor} or @samp{Info
 anchor}.  The Info file name defaults to @samp{emacs}.  For example,
 
 @smallexample
-See Info node `Font Lock' and Info node `(elisp)Font Lock Basics'.
+See Info node ‘Font Lock’ and Info node ‘(elisp)Font Lock Basics’.
 @end smallexample
 
-Finally, to create a hyperlink to URLs, write the URL between grave
-accent and apostrophe, preceded by @samp{URL}. For example,
+Finally, to create a hyperlink to URLs, write the single-quoted URL,
+preceded by @samp{URL}.  For example,
 
 @smallexample
 The home page for the GNU project has more information (see URL
-`http://www.gnu.org/').
+‘http://www.gnu.org/’).
 @end smallexample
 
 @item