Treat ' like ’ even when not matching `

This is simpler and easier to explain, and should encourage better
typography.  Do this in Electric Quote mode and when translating
quotes in docstrings.  Inspired by a suggestion by Dmitry Gutov	in:
https://lists.gnu.org/archive/html/emacs-devel/2015-08/msg00806.html
* doc/emacs/text.texi (Quotation Marks):
* doc/lispref/help.texi (Keys in Documentation):
* etc/NEWS:
Document this.
* lisp/electric.el (electric-quote-post-self-insert-function):
* src/doc.c (Fsubstitute_command_keys):
Always treat ' like ’ even when not matched by an open quote.

2 files changed, 9 insertions, 23 deletions

diff --git a/doc/emacs/text.texi b/doc/emacs/text.texi
index 5a13f208876..31760b70b4c 100644
--- a/doc/emacs/text.texi
+++ b/doc/emacs/text.texi
@@ -420,13 +420,11 @@ left and right single or double quotation marks @t{‘like this’} or
 @t{“like this”}.  Typewriter quotes are simple and portable; curved
 quotes are less ambiguous and typically look nicer.
 
-  Electric Quote mode makes it easier to type curved quotes.  It
-optionally converts a quotation's grave accent and apostrophe @t{`like
-this'} to single quotation marks @t{‘like this’}.  Similarly, it
-converts a quotation's double grave accent and double apostrophe
-@t{``like this''} to double quotation marks @t{“like this”}.  These
-conversions are suppressed in buffers whose coding systems cannot
-represent curved quote characters.
+  Electric Quote mode makes it easier to type curved quotes.  As you
+type characters it optionally converts @t{`} to @t{‘}, @t{'} to @t{’},
+@t{``} to @t{“}, and @t{''} to @t{”}.  These conversions are
+suppressed in buffers whose coding systems cannot represent curved
+quote characters.
 
 @vindex electric-quote-paragraph
 @vindex electric-quote-comment
diff --git a/doc/lispref/help.texi b/doc/lispref/help.texi
index ab884f8dc80..44c09a2085a 100644
--- a/doc/lispref/help.texi
+++ b/doc/lispref/help.texi
@@ -318,25 +318,13 @@ stands for no text itself.  It is used only for a side effect: it
 specifies @var{mapvar}'s value as the keymap for any following
 @samp{\[@var{command}]} sequences in this documentation string.
 
-@item `
-(grave accent) stands for a left quote, and alters the interpretation
-of the next unmatched apostrophe.
-
-@item '
-(apostrophe) stands for a right quote if preceded by grave accent and
-there are no intervening apostrophes.  Otherwise, apostrophe stands
-for itself.
-
 @item ‘
-(left single quotation mark) stands for a left quote.
+@itemx `
+(left single quotation mark and grave accent) both stand for a left quote.
 
 @item ’
-(right single quotation mark) stands for a right quote.
-
-@item '
-(apostrophe) stands for a right quote if
-preceded by grave accent and there are no intervening apostrophes.
-Otherwise, apostrophe stands for itself.
+@itemx '
+(right single quotation mark and apostrophe) both stand for a right quote.
 
 @item \=
 quotes the following character and is discarded; thus, @samp{\=`} puts