Re: FreeBSD make

[Ralf Wildenhues]

Hi Bob, Noah,

* Bob Friesenhahn wrote on Fri, Mar 11, 2005 at 05:47:26PM CET:
> On Fri, 11 Mar 2005, Ralf Wildenhues wrote:
> 
> >I don't know if it's worthwhile to support FreeBSD make..
> >
> >I have no idea how to keep it from looping without this patch, after
> >running the rules for vcl-tmp it always seems to want to update
> >stamp-vcl .. seems like timestamp files don't work with it at all.
> 
> Are you saying that you expect make to operate properly based on 
> side-effects? If vcl-tmp is not specified as a build target, is it not 
> a side-effect?  Why should make assume that any other files will be 
> updated except for explicit targets?

I think what I saw (but did not fully understand) was what Noah meant:

* Noah Misch wrote on Sat, Mar 12, 2005 at 03:29:36AM CET:
> 
> I have not analyzed the behavior of this particular group of rules, but the
> misbehavior sounds similar to something I have seen:
> 
> FreeBSD `make' does not conform to POSIX in its handling of modification 
> times:
> 
> $ cat >Makefile
> a: b
>       : a
> b: c
>       : b
> $ for f in b a c; do touch $f; sleep 1; done
> $ make
> : b
> : a
> $ gmake
> : b

Yes, I think this is similar to what I see here: vcl-tmp is not actually
updated because it's removed by its rules, yet `make' thinks it needs to
redo the rules for stamp-vcl.  This leads to an endless loop
(ltversion.m4 is recreated, thus all autotools rerun  -- well, they are
not actually run, because they don't exist in their default names on the
system, so it's only `missing' that is rerun -- and so on.

This bug is exposed by HEAD and branch-2-0.

Note to self: when forward-porting README notes from branch-1-5, add a
not against using FreeBSD make.  (savannah is currently down -- was it
not for the awkward arch UI, I'd have switched already.)

Regards,
Ralf