Re: Autoconf/Automake is not using version from AC_INIT

[Peter Johansson]

On 25/1/21 11:33 am, Zack Weinberg wrote:
> On Sun, Jan 24, 2021 at 7:27 PM Bob Friesenhahn
> <bfriesen@simple.dallas.tx.us> wrote:
> > AC_SUBST([CONFIGURE_DEPENDENCIES],["$CONFIGURE_DEPENDENCIES \$(top_srcdir)/ChangeLog 
> > \$(top_srcdir)/version.sh"])
> Why did you write it like this instead of
>
> CONFIGURE_DEPENDENCIES = $(top_srcdir)/ChangeLog $(top_srcdir)/version.sh
>
> directly in Makefile.am?  The way you did it, I don't think Automake
> will be aware that the variable exists.
All automake does is to declare

am__configure_deps = $(am__aclocal_m4_deps) $(CONFIGURE_DEPENDENCIES) \
    $(ACLOCAL_M4)

regardless whether 'CONFIGURE_DEPENDENCIES' is mentioned in 'Makefile.am'.

> (Also, I thought having configure not be updated when the information
> provided to AC_INIT has not changed was what you wanted to happen!)

True, but once the rule for regenerating configure is updated, one wants 
it to be updated so the rule is not triggered at every 'make'.

I've managed to reproduce the behavior Bob describes in the attached 
script. If we touch the timestamp of configure.ac, running autoconf will 
update the timestamp of configure. But if the autoconf is triggered by 
something else for example if ChangeLog has been touched, then autoconf 
won't touch configure. I suppose that behavior of autoconf is too 
established to be changed, but I think making --force default would be 
more intuitive.

One solution is to put the content of the AC_INIT arguments into 
dedicated files and add this file to  CONFIGURE_DEPENDENCIES, which will 
reduce the risk for this to happen but it's still possible that this 
file becomes newer than configure and one is back to autoconf being 
triggered at every 'make'.

Peter

test.sh
Description: application/shellscript