Re: 1e633418479926bc85ed21a4f91c845a3dd3ad66 breaks on OSX

From: Jeff King <peff@peff.net>
Date: Oct 5, 2010, 21:34 UTC
Message-ID: <20101005213401.GA22845@sigill.intra.peff.net>
In-Reply-To: <86iq1g2vhq.fsf@red.stonehenge.com>

On Tue, Oct 05, 2010 at 02:13:53PM -0700, Randal L. Schwartz wrote:

Show 20 quoted lines

> >>>>> "Ævar" == Ævar Arnfjörð Bjarmason <avarab@gmail.com> writes:
> 
> Ævar> 1e63341 is a merge commit, and none of the merged things (in the
> Ævar> commit message) seem to have anything to do with the Perl makefile
> Ævar> process.
> 
> Ævar> Can you run:
> 
> Ævar>     make -j 1 V=1
> 
> Ævar> And report what output you get?
> 
> Oddly enough, just rerunning the make again *worked*.
> 
> That's scary.
> 
> And therefore also not bisectable. :(
> 
> I imagine there's some heisenbug in there, that we'll probably trip over
> later.

This has come up before, but nobody has managed to track it down. I did some looking at it in the past, but this is all I could find:

  http://article.gmane.org/gmane.comp.version-control.git/117710

If my analysis there is right, we could probably protect against it with something like:

diff --git a/Makefile b/Makefile
index 25f94b0..aaef528 100644
--- a/Makefile
+++ b/Makefile
@@ -1596,6 +1596,10 @@ ifndef NO_PYTHON
 endif
 	$(QUIET_SUBDIR0)templates $(QUIET_SUBDIR1) SHELL_PATH='$(SHELL_PATH_SQ)' PERL_PATH='$(PERL_PATH_SQ)'
 
+ifndef NO_PERL
+all:: perl/perl.mak
+endif
+
 please_set_SHELL_PATH_to_a_more_modern_shell:
 	@$$(:)
 

But of course it's hard to test.

-Peff