m4, #line, and texinfo

[Karl Berry]

Regarding m4.

In many ways I rather like Thien-Thi's suggestion of "let the user call
m4" (if they want to), instead of embedding any particular support in
our scripts.

However, I can think of one technical reason why having native support
would be useful: line numbers in error msgs.  In that regard, it doesn't
actually matter if we are the ones calling m4 or not -- it seems like it
would be useful for the parser to understand #line (and "#") directives
and follow them.  There could be an option at some level to turn it off,
but have it enabled by default.

I just looked at the CPP manual, and there is one instance of a valid
#line directive in the source:
#line 1 "../src/gram.y"
in the source, which would cause confusion.  To allow a clean fix for
that in the source, we could define a new command @numbersign{} (or some
such) to generate the #.

I can also think of one non-technical reason to "officially" support m4,
which is so that people can expect to run texi2whatever on their
document and have it "just work".  OTOH, documents complex enough to
require m4 likely also require other external things -- this is the case
for groff and lilypond.  So that's not much of an argument.

In general, I'd be happy not to have the complexity of supporting m4 in
our scripts.

Wdyt?

karl