Re: [PATCH 1/1] stash: fix segmentation fault when files were added with intent

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Junio,

On Fri, 18 Jan 2019, Junio C Hamano wrote:

> "Matthew Kraai via GitGitGadget" <gitgitgadget@gmail.com> writes:
> 
> > From: Matthew Kraai <mkraai@its.jnj.com>
> >
> > After `git add -N <file>`, the index is in a special state. A state for
> > which the built-in stash was not prepared, as it failed to initialize
> > the `rev` structure in that case before using `&rev.pending`.
> >
> > Detailed explanation: If `reset_tree()` returns a non-zero value,
> > `stash_working_tree()` calls `object_array_clear()` with `&rev.pending`.
> > If `rev` is not initialized, this causes a segmentation fault.
> 
> It is a bit strange that the paragraph for "detailed explanation" is
> shorter than the paragraph it attempts to clarify.
> 
> Dropping those two words "Detailed explanation:" easily fixes
> awkwardness ;-).

If you must.

For me, it is not the quantity, but the quality of the words that makes it
a detailed explanation. You see, as a mathematician, I can give you a very
condensed, super detailed, complicated proof for many a lemma which is
substantially shorter than the understandable, English explanation that
I would want to give to non-mathematicians.

Likewise, if you take a step back, and try to forget for a moment that you
are very familiar with Git's source code, you will without any doubt
*have* to admit that the detailed explanation requires a *lot* of
knowledge already, while the paragraph before that does not.

So if you find that awkward, I respectfully disagree. And if you insist on
removing those "two words" (to make the paragraph *even* shorter, which is
apparently something you took exception with), I have no tools to stop
you.

Just let it be known that it is against the wish of the author of those
lines.

> > +test_expect_success 'stash --intent-to-add file' '
> > +	git reset --hard &&
> > +	echo new >file4 &&
> > +	git add --intent-to-add file4 &&
> > +	test_when_finished "git rm -f file4" &&
> > +	test_must_fail git stash
> > +'
> 
> This still must fail because an index with an I-T-A cannot be
> included in a stash, but test_must_fail will make sure that the
> command does not suffer an uncontrolled crash.  Good.

Indeed. And Matthew even adopted your preferred strategy of combining the
demonstration of the bug with the fix. In the meantime, I have found the
totally intuitive (and equally documented) command line that I can use
when I want to see whether a given branch is buggy and when I cannot
simply `git cherry-pick <commit-demonstrating-a-bug>`:

	git cherry-pick <commit-fixing-the-bug-and-adding-a-test>
	git checkout HEAD^ -- :^/t/

Ciao,
Johannes