Re: [PATCH 1/3] range-diff: refactor check for commit range

Hi Junio

On 22/01/2021 21:59, Junio C Hamano wrote:

Phillip Wood [off-list ref] writes:

quoted

quoted

   +static int is_range(const char *range)
+{
+	return !!strstr(range, "..");
+}

If the user wrongly passes two arguments referring to single commits
with `:/<text>` or `@{/<text>}` where text contains ".." this will
give a false positive.

True.  I do not think this aims to be complete revision parser in
the first place, though.

Yes but it affects the error message given to the user. If I run

git range-diff $(git rev-parse HEAD^{/..q}) $(git rev-parse HEAD^{/..x})

It fails immediately with

fatal: no .. in range: 'b60863619cf47b2e1e891c2376bd4f6da8111ab1'

This patch improves the error message to say it is not a range

but

git range-diff HEAD^{/..q} HEAD^{/..x}

runs for several minutes without producing any output and eventually 
fails with

fatal: Out of memory, malloc failed (tried to allocate 33846432676 bytes)

So I think it would be helpful to be more careful here.

Best Wishes

Phillip

It is tempting to at least idly speculate if an approach to run
setup_revisions() on argument is_range() takes and checking the
result would yield a more practical solution.  I would imagine that
we would want to see in the resulting revs.pending has at least one
positive and one negative, and none of them have SYMMETRIC_LEFT set
in their .flags word.

     Side note: Strictly speaking, people could wish "rev" to mean
                "everything reachable from the rev, down to root", so
                requiring one negative may technically be a wrong
                thing, but in the context of "range-diff", I am not
                sure how useful such a behaviour would be.