bug#20707: [PROPOSED PATCH] Use curved quoting in C-generated errors

[Paul Eggert <eggert@cs.ucla.edu>]

Alan Mackenzie wrote:
>> Curved single quotes are also "working" characters, both in Emacs
>> >(master branch) and in Texinfo (latest stable version).
> They're not

It sounds like your definition of "working" differs from what I thought it 
meant.  I thought you were using "working" to mean that a character has a 
special function in Emacs or in the file that one is editing.  But as I 
understand it now, by "working" you mean that it's a character on your keyboard. 
  If so, then yes, you're right, curved single quotes are typically not 
"working" characters.  But I fail to see the significance of this point.  For 
example, the newline character is not a "working" character on my keyboard, but 
that doesn't mean we should exclude newlines from our source files.

>> >It's true that not every keyboard can generate them in every Emacs
>> >context with just a single keypress, ....
>> >but that's also true for many ASCII characters.
> Also untrue, for the large class of keyboards which are based on the
> Latin alphabet.

I have such a keyboard, and when I type Return, Emacs doesn't put a carriage 
return into a typical buffer; it does something else.  Or when I type the \ key 
in a Lisp string, Emacs doesn't put a \ into the string; it does something else. 
  Or when I type a space character when searching, Emacs doesn't search for a 
space; it does something else.  In all these cases, if I really want to get 
exactly the ASCII character in question, I have to do something other than type 
a key labeled by that character.  And my point was that this is something that 
many ASCII characters have in common with curved quotes.

> the standard default Linux console font, default8x16

It's news to me that this is the standard default Linux console font.  It's not 
available in Ubuntu or in Fedora, which are popular GNU/Linux distributions. 
Perhaps it's something used at a low level while booting?  That would make 
sense, if it uses the same encoding that the IBM PC used back in 1981.  Anyway, 
it doesn't seem to be of much practical relevance to this thread.