bug#31624: 27.0; (elisp) `Syntax Flags'

[Alan Mackenzie]

Hello, Drew.

In article <mailman.627.1527518890.1292.bug-gnu-emacs@gnu.org> you wrote:
> Something seems to be missing. This node refers to "a" style, but that
> seems to be defined nowhere.  The node defines "comment style" this way:

>   A comment style is a set of flags 'b', 'c', and 'n', ...

> No mention of style "a" there.  What is style "a"?  I don't see it
> specified anywhere.

> Presumably style "a" is some set composed of the flags 'b', 'c', and
> 'n', but what set?

When neither flag 'b' nor flag 'c' is set, you have style "a".  

> And what about the relation between those "flags" and the "styles"?

When 'b' is set, you have style "b", when 'c' is set, you have style
"c".  I think having both of them set is undefined (but it does leave
room for a style "d" (shudder!)).

> If a flag is an element in a set that is a style, why does the doc use
> chars b and c to name both flags and styles - that just confuses
> things.  If you want to relate style "b" to flag 'b' then maybe use
> "B", not "b", as the style name.

I think that would be less confusing if something like my first sentence
were in the doc somewhere.

> (Yes, I realize that this text is very old - at least as old as Emacs
> 20.  But it seems like it could/should be clearer.)

I though style "c" was somewhat younger.  Maybe not.  But maybe it could
be clarified.

> In GNU Emacs 27.0.50 (build 3, x86_64-w64-mingw32)
>  of 2018-03-21
> Repository revision: e70d0c9e66d7a8609450b2889869d16aeb0363b5
> Windowing system distributor `Microsoft Corp.', version 6.1.7601
> Configured using:
>  `configure --without-dbus --host=x86_64-w64-mingw32
>  --without-compress-install -C 'CFLAGS=-O2 -static -g3''

-- 
Alan Mackenzie (Nuremberg, Germany).