Re: [PATCH v2 4/4] t/Makefile: introduce TEST_SHELL_PATH

[Jeff King <peff@peff.net>]

On Fri, Dec 15, 2017 at 08:58:22AM -0800, Junio C Hamano wrote:

> Jeff King <peff@peff.net> writes:
> 
> > I think (4) and (5) are the only things that actually change the
> > behavior in a meaningful way. But they're a bit more hacky and
> > repetitive than I'd like. Especially given that I'm not really sure
> > we're solving an interesting problem. I'm happy enough with the patch as
> > shown, and I do not recall anybody complaining about the current
> > behavior of these options.
> 
> OK.  Thanks for thinking it through.

I took one final look at this, wondering if it ought to follow the
"write to BUILD-OPTIONS only if set" pattern that some other variables
do. But I think that just ends up more confusing, because of the way we
use the variable from both the Makefile and test-lib.sh. So it makes
this work:

  make
  make -C t TEST_SHELL_PATH=whatever

but not quite this:

  make TEST_SHELL_PATH=one
  make -C t TEST_SHELL_PATH=two

because in the second case, we use "two" to invoke the test script, but
a "--tee" re-exec would use "one". Which is pretty subtle.

I really wish there was a way for a shell script to find out which
interpreter it was currently using, but I couldn't come up with a
portable way to do so (on some systems, /proc/$$/exe works, but that's
obviously not something we should count on).

So anyway. I think I'm OK with the series as-is.

-Peff