Re: [PATCH 6/6] diff.c: detect blocks despite whitespace changes

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

Stefan Beller <sbeller@google.com> writes:

> Originally I wanted to do that, see prep work in [1], but Jeff explained that
> the additional pointer in the compare function is **not** supposed to be
> a additional payload (such as the diff options specifying the white space
> options.)
>
> [1] https://public-inbox.org/git/20170512200244.25245-1-sbeller@google.com/

Ah, yes, keydata is a wrong thing to use to give additional hint to
the eqv function.  We do need to fix the function signature of
hashmap_cmp_fn.  It is common for us to want to use a single
implementation of an eqv function that can be configured to behave
slightly differently but the customization will stay the same
throughout the lifetime of a hashmap.  IOW, hashmap_init() needs to
be able to take a pointer to such a configuration data
(e.g. diff_options), and then the comparison made between two
elements that hash to the same bucket needs to be given not just the
two elements but also that configuration data to tweak the function.