On 2012-11-12 16:09 -0700, Eric Blake wrote: > On 11/12/2012 03:41 PM, Nick Bowler wrote: > > Sorry, I don't understand. You seem to be claiming that the addition of > > AC_CONFIG_MACRO_DIRS (an entirely new macro, with documented behaviour) > > to Autoconf will somehow break the following pattern if we don't also > > change the definition of AC_CONFIG_MACRO_DIR? > > > > configure.ac: > > AC_CONFIG_MACRO_DIR([foo]) > > > > Makefile.am: > > ACLOCAL_AMFLAGS = -I foo > > > > What breaks? How does it break? Why will this not continue to work > > For this usage, nothing breaks. It continues to work as it has done > (well, new enough automake might start complaining about your use of > obsolete ACLOCAL_AMFLAGS, but that's not autoconf's fault). The key is > that you used AC_CONFIG_MACRO_DIR only once in this example, so it will > continue to function, because there is no ambiguity.
What I meant is: if we do *not* make any change at all to AC_CONFIG_MACRO_DIR from its behaviour in Autoconf 2.69, how does this pattern break? I hope we can all agree that this is the common case. If nothing breaks, then remind me why we need to change AC_CONFIG_MACRO_DIR at all? > > exactly as it has in the past if we do not keep AC_CONFIG_MACRO_DIR's > > definition exactly as it is right now, i.e.: > > > > AC_DEFUN([AC_CONFIG_MACRO_DIR], []) > > This definition is one way of spelling 'no effect except for use by > tracing'. Another way of spelling 'no effect except for use by tracing' > is the one now in autoconf.git, but where the tracing now goes through > the AC_CONFIG_MACRO_DIR_TRACE macro, and where we have imposed an > interaction with the brand-new macro (if you mix the old and new macro, > then the old macro must be used first, to avoid ambiguity). Right, but you are changing what gets traced -- and you are making this change with the intent that the behaviour of other tools will also change. And to be clear: this patch does more than what you describe here. In addition to the changed tracing, and the restrictions on use with the new AC_CONFIG_MACRO_DIRS, it also adds additional failure cases not related to either of these things (described earlier). Cheers, -- Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)
