On 05/02/2016 12:10 PM, Alan Mackenzie wrote:
>
>> (message "%s" M) is the usual way to output a message M without
>> formatting it, and something like this is needed anyway if M might
>> contain %.
> That is the case for a string that might contain percent characters.  It
> is not the case for a string known to be without percents.

Sure, but the most common problem here is using (message M) to output an 
arbitrary string M that is under user control, which is why the advice 
about (message "%s" M) is helpful. This advice works for all format 
directives, not just % directives.

> There is no mention of its corruption of quotes in
> `messages''s doc string.

Thanks, good point. I fixed it by installing the attached patch, which 
should address the other documentation problems you mention too.

> It appears to me that these substitutions are only done on pairs of
> quote marks, not single quotes.

What gives you that impression? Substitutions are done on all quotes, 
not just paired quotes.

> Properly, for me, means that it handles percent escape sequences, AND
> OTHERWISE LEAVES THE STRING UNCHANGED.

This alternative was considered when designing text-quoting-style, but 
at the time we didn't see a need for the extra complexity. The 
particular glitch you ran into is not a strong argument for revisiting 
this now.

> Why is it not in the section "incompatible Lisp changes"?

It is in that section, under "** New variable 'text-quoting-style' ...".