From: Jeff King <peff@peff.net>
Date: Fri, 10 Dec 2021 09:47:23 GMT
Subject: Re: [PATCH v2 1/2] t1510: remove need for "test_untraceable", retain coverage
Message-ID: <YbMiK1wHzBfYvK2a@coredump.intra.peff.net>
In-Reply-To: <20211202191635.GB1991@szeder.dev>

On Thu, Dec 02, 2021 at 08:16:35PM +0100, SZEDER Gábor wrote:

> > @@ -62,7 +59,7 @@ test_repo () {
> >  			export GIT_WORK_TREE
> >  		fi &&
> >  		rm -f trace &&
> > -		GIT_TRACE_SETUP="$(pwd)/trace" git symbolic-ref HEAD >/dev/null &&
> > +		GIT_TRACE_SETUP="$(pwd)/trace" git symbolic-ref HEAD >/dev/null 2>>stderr &&
> 
> I suspect that it's lines like this that make Peff argue for
> BASH_XTRACEFD :)
> 
> While this is not a compound command, it does contain a command
> substitution, and the trace generated when executing the command in
> that command substitution goes to the command's stderr, and then,
> because of the redirection, to the 'stderr' file.

Better still, the behavior varies between shells:

  $ bash -c 'set -x; FOO=$(echo foo) echo main >stdout 2>stderr; set +x; grep . stdout stderr'
  ++ echo foo
  + FOO=foo
  + echo main
  + set +x
  stdout:main

  $ dash -c 'set -x; FOO=$(echo foo) echo main >stdout 2>stderr; set +x; grep . stdout stderr'
  + FOO=foo echo main
  + set +x
  stdout:main
  stderr:+ echo foo

-Peff