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

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

On 06/02/2015 08:51 AM, Dmitry Gutov wrote:
> GCC outputs curly quotes, but doesn't use them in the source code. So 
> that's still an option. 

Yes, and the changes installed into the master preserve that option for 
Emacs as well.  Eventually we should move away from the idea of quoting 
`like this' in the source code with the understanding that the quotes 
are transliterated for the user, as in the long run that'll be one more 
annoying thing to deal with, but in the meantime it's a reasonable 
transition strategy to stick with ASCII-only formats in diagnostics.

In this sense, the patch proposed in Bug#20707 goes too far, as it would 
require either curved quotes in C source strings, or ugly 
circumlocutions like "Error: "uLSQ"%s"uRSQ" is invalid" in place of 
"Error: ‘%s’ is invalid".  So I plan to draft a different approach that 
will be more like what GCC does.