Re: [bug-patch] is this a bug?

[Steve Summit]

Andreas wrote:
> ...the patch could only be applied by ignoring one line of context.
> This may seem surprising, but patch assumes that hunks that have more
> context at the beginning than at the end must apply at the end...

That is surprising.  Thanks for the explanation.

Is there a document anywhere that describes patch's algorithm
in full?  "Comparing and Merging Files" by MacKenzie, Eggert,
and Stallman seems to have most of it, but it doesn't mention
this nuance.

> Always be careful with patches that apply with fuzz. When applying
> patches automatically, use option -F0.

Or in any case, use option -Fn, where n is less than the context
in your diff.  (And it doesn't make the patch succeed in my case,
but at least it fails instead of applying wrongly.)

I wonder if it would be worthwhile to have a companion to -Fn,
perhaps -Cm, meaning "don't strip fuzz to leave less than m lines
of context".  I'd find that easier to think about, especially if
for whatever reason I couldn't predict the contextitude of the
incoming patches.