autoconf macro AC_FUNC_SELECT

[Jim V. Z. <jr...@co...>]

Lately when I do "cvs update" I get a series of warning like this:

 cvs server: conflict: Makefile.in is modified but no longer in the repository

I tried to fix that by moving the files aside and recreating them, but
had a lot of trouble getting configuration working again.  I got a lot
of warnings from automake (or maybe it was autoconf) about an invalid
macro AC_FUNC_SELECT.  "prepare" didn't help.  Eventually I stumbled
on a combination of automake, autoconf, aclocal, and prepare that is
working.  However, there seems to be a problem...

prepare claims:

  # Note that both autoconf 2.13/automake 1.5 and autoconf 2.5x/automake
  # 1.7 or newer may be used, although the gnuplot project continues to
  # use the former
  
However, autoconf 2.13 quits immediately because configure.in contains:

  AC_PREREQ(2.52)

I guess the comment in prepare is out of date.

configure.in also contains:

  dnl Argument types of select()
  AC_FUNC_SELECT

but AC_FUNC_SELECT is not documented in either autoconf 2.13 or 2.58.

Indeed, when I run configure I get this warning:
  
  ./configure: line 6936: AC_FUNC_SELECT: command not found

I guess it was replaced by AC_FUNC_SELECT_ARGTYPES, which
first appeared in autoconf 2.13 (May '99). 

I trace the usage like this:
  src/gplt_x11.c uses SELECT_FD_SET_CAST like this:

	nf = select(nfds, SELECT_FD_SET_CAST & tset, 0, 0, timer);

  which is defined in stdfn.h like this:

        #ifndef SELECT_FD_SET_CAST
        # define SELECT_FD_SET_CAST
        #endif

  In principle, SELECT_FD_SET_CAST could also be defined in config.h, 
  depending on config.hin and the results of autoconf tests
(e.g. AC_FUNC_SELECT). Apparently since AC_FUNC_SELECT never runs,
SELECT_FD_SET_CAST never really contributes anything.
  
I suggest:
  update the comment in "prepare" to require autoconf 2.5x/automake 1.7
  delete the reference to AC_FUNC_SELECT in configure.in
  delete SELECT_FD_SET_CAST from gplt_x11.c.

Alternatively:
  configure.in should call AC_FUNC_SELECT_ARGTYPES
  in gplt_x11.c (and also in src/fit.c), the second argument to select
should be cast to SELECT_TYPE_ARG234.  Likewise cast the first
argument to SELECT_TYPE_ARG1 and the last argument to SELECT_TYPE_ARG5.
  
Are the nonstandard version of select() common enough to justify the latter?

		- Jim Van Zandt