This bug is a funny one, I think.
In flex (lexer) configure.ac, I use "dnl" comments within
AC_CHECK_FUNCS for inline notes, like this:
# --------------------------------
AC_CHECK_FUNCS([dnl
pow dnl Used only by "examples/manual/expr"
setlocale dnl Needed only if NLS is enabled
reallocarr dnl NetBSD function. Use reallocarray if not available.
reallocarray dnl OpenBSD function. We have replacement if not available.
])
# --------------------------------
But this syntax will make autoheader generate unneeded HAVE_ macros in
config.h.in:
/* Define to 1 if you have the `available.' function. */
#undef HAVE_AVAILABLE_
/* Define to 1 if you have the `by' function. */
#undef HAVE_BY
/* Define to 1 if you have the `dnl' function. */
#undef HAVE_DNL
The dnl comments should be ignored when generating config.h.in header,
or at least document that users should not add comments from within
AC_CHECK_FUNCS.
Note: Tested this with Autoconf 2.69 and Automake 1.15.1. Detailed
steps to reproduce:
$ git clone --depth 1 --branch v2.6.4 https://github.com/westes/flex flex
$ cd flex
$ autoheader
$ cat src/config.h.in
See the useless HAVE_ macros in the header.
