Re: t4204-patch-id failures

[Armin Kunaschik <megabreit@googlemail.com>]

On Tue, May 24, 2016 at 12:23 AM, Junio C Hamano <gitster@pobox.com> wrote:
> Junio C Hamano <gitster@pobox.com> writes:

> Having said all that, this illustrates the root cause of different
> behaviours better, but it is harder to reason about than simply
> changing the variable name used in this shell function.  POSIX reads
> a bit fuzzy to me around here:
>
>     ... each command of a multi-command pipeline is in a subshell
>     environment; as an extension, however, any or all commands in a
>     pipeline may be executed in the current environment. All other
>     commands shall be executed in the current shell environment.
>
> That essentially says nothing useful; it does not guarantee that
> each command on a pipeline runs in its own subshell environment, and
> a portable script must be prepared to see some of them run in the
> current shell environment.

Writing portable shell scripts sometimes is quite a mess :-)

> So let's do this instead:
>
> -- >8 --
> Subject: t4204: do not let $name variable clobbered
>
> test_patch_id_file_order shell function uses $name variable to hold
> one filename, and calls another shell function calc_patch_id as a
> downstream of one pipeline.  The called function, however, also uses
> the same $name variable.  With a shell implementation that runs the
> callee in the current shell environment, the caller's $name would
> be clobbered by the callee's use of the same variable.
>
> This hasn't been an issue with dash and bash.  ksh93 reveals the
> breakage in the test script.

Maybe add ksh88 too, just to be "feature" complete.

> Fix it by using a distinct variable name in the callee.

Agreed.

> Reported-by: Armin Kunaschik <megabreit@googlemail.com>
> Signed-off-by: Junio C Hamano <gitster@pobox.com>