Re: stdint generation

[Ralf Wildenhues]

Hello Bruno,

* Bruno Haible wrote on Mon, Oct 15, 2007 at 09:19:01PM CEST:
> Sam Steingold wrote:
> > gnulib/gnulib/m4/stdint offers a multi-line sed rule for generating 
> > stdint.h from stdint_.h,
> > why do I need to maintain the sed command by hand?
> > why can't this be done by config.status?
[...]
> Regarding gnulib itself: Modules in gnulib are made of source code in lib/,
> autoconf macros in m4/, and Makefile.am rules in modules/$module. We do the
> split between what goes into m4/stdint_h.m4 and what goes into modules/stdint
> by considering what is most natural. Creating files is most conveniently done
> in a Makefile, not in config.status. (Because config.status is not invoked
> when doing "make clean", "make dist" or similar, and because expressing file
> names in config.status is harder, since config.status is usually in a 
> different
> directory than the files being built.)

IMVHO it is not harder, but it can make your life simpler: If you would
instead generate files by config.status, you would not have to keep the
list of substitutions in modules/stdint (and others) up to date.  So
from

  # We need the following in order to create <stdint.h> when the system
  # doesn't have one that works with the given compiler.
  stdint.h: stdint.in.h
          rm -f address@hidden $@
          { echo '/* DO NOT EDIT! GENERATED AUTOMATICALLY! */'; \
            sed -e 's/@''HAVE_STDINT_H''@/$(HAVE_STDINT_H)/g' \
[...lots of lines...]
                -e 's/@''WINT_T_SUFFIX''@/$(WINT_T_SUFFIX)/g' \
                < $(srcdir)/stdint.in.h; \
          } > address@hidden
          mv address@hidden $@
  MOSTLYCLEANFILES += stdint.h stdint.h-t

you'd go to:

  # We need the following in order to create <stdint.h> when the system
  # doesn't have one that works with the given compiler.
  stdint.h: stdint.in.h
          cd $(top_builddir) && ./config.status 
'--file=$(subdir)/$@:$(abs_srcdir)/stdint.in.h'
  MOSTLYCLEANFILES += stdint.h

and then the first line of stdint.in.h could read
  /* @configure_input@ */

which, when substituted, will sound a bit less harsh than your current
warning; if you want to keep the exact warning, then I guess nothing
keeps you from
  AC_SUBST([gnulib_configure_input],
   [DO NOT EDIT! GENERATED AUTOMATICALLY!])

Note that, this way, the rebuild semantics have not changed at all:
stdint.h is not listed in AC_CONFIG_FILES, it does not get created at
  ./config.status

time.  The only consequence would be less typing in modules/stdint, and
a bit slower build (because config.status would be executed for each
replacement header).


Of course, generation at the end of `configure' could be a further step:
use
  AC_CONFIG_FILES([$sourcebase/stdint.h])

and add $(top_builddir)/config.status to the list of dependencies of the
above rule.  This would only be telling the truth: the dependency exists
already now, in current gnulib, however it's not spelled out, I assume
trading efficiency in the common case for reliable rebuilds.

If the AC_CONFIG_FILES step is done, the stdint.h rule can be simplified
to
          cd $(top_builddir) && ./config.status $(subdir)/$@


If you like any of the two steps, I can prepare a patch for them.

Cheers,
Ralf