mercurial/mpatch.h

copies: don't include copies that are not in source in directory move

I've been working on a rewrite of mergecopies(). I compared the output
of the rewritten version with the current version. I noticed that
between FIREFOX_NIGHTLY_59_END and FIREFOX_BETA_60_BASE in the
mozilla-unified repo, there were many copies that the current version
detected that the rewritten version did not. One example was
js/src/gc/Iteration.h -> js/src/gc/PublicIterators.h. Then I realized
that js/src/gc/Iteration.h doesn't even exist in
FIREFOX_NIGHTLY_59_END.

This patch adds a filtering step for the "fullcopy" dict. It turns out
that that change also affects the test for issue5020 in
test-merge-criss-cross.t. The 'dm' action no longer happens there. At
first I thought that the test case change meant that this patch was
broken, but I think it's actually correct tha the 'dm' action should
not happen there. The result of the bid merge is still the same.

I suspect this filtering is a better solution for the issue than
41f6af50c0d8 (merge: fix crash on criss cross merge with dir move and
delete (issue5020), 2017-01-31). I also suspect that it was broken
just a few months earlier by a005c33d0bd7 (mergecopies: add logic to
process incomplete data, 2016-10-04). Note that bid merge had been
enabled for a few years at that point, since 19903277f035 (merge: use
bid merge by default (BC), 2014-10-01).

This patch is still just a workaround. It will be cleaned up soon
(with the rewrite of mergecopies()). But doing this in a separate
patch makes later patches easier to understand and gives a place to
explain why this is changing.

Differential Revision: https://phab.mercurial-scm.org/D6244

#ifndef _HG_MPATCH_H_
#define _HG_MPATCH_H_

#define MPATCH_ERR_NO_MEM -3
#define MPATCH_ERR_CANNOT_BE_DECODED -2
#define MPATCH_ERR_INVALID_PATCH -1

struct mpatch_frag {
	int start, end, len;
	const char *data;
};

struct mpatch_flist {
	struct mpatch_frag *base, *head, *tail;
};

int mpatch_decode(const char *bin, ssize_t len, struct mpatch_flist **res);
ssize_t mpatch_calcsize(ssize_t len, struct mpatch_flist *l);
void mpatch_lfree(struct mpatch_flist *a);
int mpatch_apply(char *buf, const char *orig, ssize_t len,
                 struct mpatch_flist *l);
struct mpatch_flist *
mpatch_fold(void *bins, struct mpatch_flist *(*get_next_item)(void *, ssize_t),
            ssize_t start, ssize_t end);

#endif