The manual states in '(texinfo)Invoking Macros':
Passing macro arguments containing commas requires care, since commas
also separate the arguments. To include a comma character in an
argument, the most reliable method is to use the ‘@comma{}’ command.
For ‘texi2any’, you can also prepend a backslash character, as in ‘\,’,
but this does not work with TeX.
I found in the groff manual there was incorrect output for input
like the following (modified slightly to work as a minimal example):
@macro Defesc{name, delimI, arg, delimII}
@deffn Escape @t{\name\\delimI\}@var{\arg\}@t{\delimII\}
@c
@end macro
@macro endDefesc
@end deffn
@end macro
@Defesc {\\\,, , , }
@cindex left italic correction (@code{\,})
Modify the spacing of the following glyph so that the spacing between
that glyph and the preceding glyph is correct if the preceding glyph is
@endDefesc
The first argument to @Defesc is supposed to be interpreted as '\,' but
instead it is taken as '\\' and there is a spurious comma afterwards.
(I check on the groff webpages and the PDF manual they offer for download
does actually have the correct output, which is likely because they
macro-expand with texi2any before TeX processing.)
Nonetheless, texi2any does not warn about this construct which is incorrect
for TeX. We could fix this in two ways:
* Make \, work in TeX
* Issue a warning from texi2any to say that @comma{} should be used instead
Another way of allowing commas in macro arguments is to use @asis:
@Defesc {@asis{\,}, , , }
which may be nicer than
@Defesc {\@comma{}, , , }
We could recommend @asis in the manual and/or a new warning message.
