Re: [PATCH 2/2] Allow passing pipes for input pipes to diff --no-index

[Thomas Guyot-Sionnest <tguyot@gmail.com>]

Hi Jeff,

On Fri, 18 Sep 2020 at 13:19, Jeff King <peff@peff.net> wrote:
> On Fri, Sep 18, 2020 at 12:34:48PM -0400, Thomas Guyot-Sionnest wrote:
> But we do have to account for this in the test suite, which must be able
> to run under a vanilla POSIX shell. So you'd probably want to set up a
> prerequisite that lets us skip these tests on other shells, like:

Indeed, the bash test library that was suggested earlier may be better
as it exec() bash rather than skipping tests. Testing as a prereq
works, another approach which may be harder to swallow but allow
testing when default shell is /bin/sh is to run each git command
through bash - could be coupled with a dep if bash isn't installed at
all.

> Though it is a little sad that people running the suite with a vanilla
> /bin/sh like dash wouldn't ever run the tests. I wonder if there's a
> more portable way to formulate it.

Debian defaults to dash, a minimalistic and afaik POSIX-compliant shell.

> Getting back to the overall feature, this is definitely something that
> has come up before. The last I know of is:
>
>   https://lore.kernel.org/git/20181220002610.43832-1-sandals@crustytoothpaste.net/
>
> which everybody seemed to like the direction of; I suspect the original
> author (cc'd) just never got around to it again. Compared to this
> approach, it uses a command-line option to avoid dereferencing symlinks.
> That puts an extra burden on the caller to pass the option, but it's way
> less magical; you could drop all of the "does this look like a symlink
> to a pipe" heuristics. It would also be much easier to test. ;)

Thanks for the info. Another consideration is how other commands -
diff, vim, sed, curl, etc can take input the same way, so being able
to swap-in git is a plus imho,and one less switch to learn (or even
learn about, I never looked for one for this issue).

Regards,

Thomas