Re: [PATCH] t/test_lib: avoid naked bash arrays in file_lineno

[Carlo Arenas <carenas@gmail.com>]

On Thu, May 7, 2020 at 7:53 AM Junio C Hamano <gitster@pobox.com> wrote:
>
> Carlo Marcelo Arenas Belón  <carenas@gmail.com> writes:
>
> > 662f9cf154 (tests: when run in Bash, annotate test failures with file
> > name/line number, 2020-04-11), introduces a way to report the location
> > (file:lineno) of a failed test case by traversing the bash callstack.
> >
> > The implementation requires bash and is therefore protected by a guard
> > but NetBSD sh will still have to parse the function and therefore will
> > result in:
> >
> >   ** t0000-basic.sh ***
> >   ./test-lib.sh: 681: Syntax error: Bad substitution
> >
> > Enclose the bash specific code inside an eval to avoid parsing errors
> > and while at it, simplify the logic so that instead of traversing the
> > callstack just pop the two topmost entries that are required.
> >
> > Helped-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
>
> Is the rewritten bash-snippet in the evaled text what Dscho
> suggested us to use, or is it totally yours?

It is all mine, but Dscho's detailed description of the implementation it
is replacing allowed me to validate its correctness (under the documented
use cases)

my hope was that Dscho's and Danh would quickly agree as it is simpler
and faster, as well as providing some more description of its operation in
the commit message for future reviewers.

> I know Dscho helped to
> shoot down some "simpler" reimplementations you came up with,
> pointing out how they were broken, but it is unclear how we ended up
> with this version.

I made the wrong assumptions while focusing on translating the code
to posix sh and ended up with a broken version.

Another reason why I did the "while at it" was to avoid someone else
having the same problem by simplifying it and making sure that uncommon
syntax (like ${1+$1..}, or the use of $LINENO which would never apply
to our code)
weren't needed.

> I wish you didn't do the "while at it" rewrite in the same patch.
> If it were only "put bash-only stuff in an evaled string", it would
> have been a lot more comfortable applying it and merging quickly
> down, as it would be clear that we won't be breaking bash codepath
> and we'd be helping other shells.  With the "while at it", you made
> it quite unclear.

fair enough, and considering that "fixing other shell" has higher priority
will send a v2 to do so.

will do any "simplification" on a follow up and try to monitor these issues
early

Carlo