Re: [PATCH] sparse-checkout: be consistent with end of options markers

[Junio C Hamano <gitster@pobox.com>]

"Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com> writes:

> From: Elijah Newren <newren@gmail.com>
>
> 93851746 (parse-options: decouple "--end-of-options" and "--",
> 2023-12-06) updated the world order to make callers of parse-options
> that set PARSE_OPT_KEEP_UNKNOWN_OPT responsible for deciding what to
> do with "--end-of-options" they may see after parse_options() returns.
>
> This made a previous bug in sparse-checkout more visible; namely,
> that
>
>   git sparse-checkout [add|set] --[no-]cone --end-of-options ...
>
> would simply treat "--end-of-options" as one of the paths to include in
> the sparse-checkout.  But this was already problematic before; namely,
>
>   git sparse-checkout [add|set| --[no-]cone --sikp-checks ...
>
> would not give an error on the mis-typed "--skip-checks" but instead
> simply treat "--sikp-checks" as a path or pattern to include in the
> sparse-checkout, which is highly unfriendly.
>
> This behavior begain when the command was converted to parse-options in
> 7bffca95ea (sparse-checkout: add '--stdin' option to set subcommand,
> 2019-11-21).  Back then it was just called KEEP_UNKNOWN. Later it was
> renamed to KEEP_UNKNOWN_OPT in 99d86d60e5 (parse-options:
> PARSE_OPT_KEEP_UNKNOWN only applies to --options, 2022-08-19) to clarify
> that it was only about dashed options; we always keep non-option
> arguments.  Looking at that original patch, both Peff and I think that
> the author was simply confused about the mis-named option, and really
> just wanted to keep the non-option arguments.  We never should have used
> the flag all along (and the other cases were cargo-culted within the
> file).
>
> Remove the erroneous PARSE_OPT_KEEP_UNKNOWN_OPT flag now to fix this
> bug.  Note that this does mean that anyone who might have been using
>
>   git sparse-checkout [add|set] [--[no-]cone] --foo --bar
>
> to request paths or patterns '--foo' and '--bar' will now have to use
>
>   git sparse-checkout [add|set] [--[no-]cone] -- --foo --bar
>
> That makes sparse-checkout more consistent with other git commands,
> provides users much friendlier error messages and behavior, and is
> consistent with the all-capps warning in git-sparse-checkout.txt that
> this command "is experimental...its behavior...will likely change".  :-)
>
> Signed-off-by: Elijah Newren <newren@gmail.com>
> ---

Nicely described.

Apparently we do not have an existing test to cover the case of
"misspelt options becoming a pattern" that this bugfix corrects;
otherwise we would have a s/failure/success/ to update such an older
expectation, and have to wonder if the existing behaviour is
intentional.  Since there is no such test, we can feel a bit safer
in "fixing" this odd behaviour.

Also, this corrects "--end-of-options" that becomes one of the
patterns.  Such a bug was not detected in our test suite.

So we should at least have two new tests.

 (1) Pass "--foo" without the end of options marker and make sure we
     error out, instead of making it as one of the patterns.

 (2) Pass "--end-of-options foo" and make sure the command succeeds,
     an d"--end-of-options" does not become on eof the patterns.

Thanks.