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resolve-undo: allow resurrecting conflicted state that resolved to deletion 

The resolve-undo index extension records up to three (mode, object
name) tuples for non-zero stages for each path that was resolved,
to be used to recreate the original conflicted state later when the
user requests.

The unmerge_index_entry_at() function uses the resolve-undo data to
do so, but it assumes that the path for which the conflicted state
needs to be recreated can be specified by the position in the
active_cache[] array.  This obviously cannot salvage the state of
conflicted paths that were resolved by removing them.  For example,
a delete-modify conflict, in which the change whose "modify" side
made is a trivial typofix, may legitimately be resolved to remove
the path, and resolve-undo extension does record the two (mode,
object name) tuples for the common ancestor version and their
version, lacking our version.  But after recording such a removal of
the path, you should be able to use resolve-undo data to recreate
the conflicted state.

Introduce a new unmerge_index_entry() helper function that takes the
path (which does not necessarily have to exist in the active_cache[]
array) and resolve-undo data, and use it to reimplement unmerge_index()
public function that is used by "git rerere".

The limited interface is still kept for now, as it is used by "git
checkout -m" and "git update-index --unmerge", but these two codepaths
will be updated to lift the assumption to allow conflicts that resolved
to deletion can be recreated.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
maint
Junio C Hamano 2023-07-31 15:44:04 -07:00
parent 91e07058c5
commit fe83269e16
2 changed files with 44 additions and 5 deletions
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48
resolve-undo.c
View File

@ -182,19 +182,57 @@ void unmerge_marked_index(struct index_state *istate)
}
}

int unmerge_index_entry(struct index_state *istate, const char *path,
struct resolve_undo_info *ru)
{
int i = index_name_pos(istate, path, strlen(path));

if (i < 0) {
/* unmerged? */
i = -i - 1;
if (i < istate->cache_nr &&
!strcmp(istate->cache[i]->name, path))
/* yes, it is already unmerged */
return 0;
/* fallthru: resolved to removal */
} else {
/* merged - remove it to replace it with unmerged entries */
remove_index_entry_at(istate, i);
}

for (i = 0; i < 3; i++) {
struct cache_entry *ce;
if (!ru->mode[i])
continue;
ce = make_cache_entry(istate, ru->mode[i], &ru->oid[i],
path, i + 1, 0);
if (add_index_entry(istate, ce, ADD_CACHE_OK_TO_ADD))
return error("cannot unmerge '%s'", path);
}
return 0;
}

void unmerge_index(struct index_state *istate, const struct pathspec *pathspec)
{
int i;
struct string_list_item *item;

if (!istate->resolve_undo)
return;

/* TODO: audit for interaction with sparse-index. */
ensure_full_index(istate);
for (i = 0; i < istate->cache_nr; i++) {
const struct cache_entry *ce = istate->cache[i];
if (!ce_path_match(istate, ce, pathspec, NULL))

for_each_string_list_item(item, istate->resolve_undo) {
const char *path = item->string;
struct resolve_undo_info *ru = item->util;
if (!item->util)
continue;
i = unmerge_index_entry_at(istate, i);
if (!match_pathspec(istate, pathspec,
item->string, strlen(item->string),
0, NULL, 0))
continue;
unmerge_index_entry(istate, path, ru);
free(ru);
item->util = NULL;
}
}

1
resolve-undo.h
View File

@ -18,6 +18,7 @@ void resolve_undo_write(struct strbuf *, struct string_list *);
struct string_list *resolve_undo_read(const char *, unsigned long);
void resolve_undo_clear_index(struct index_state *);
int unmerge_index_entry_at(struct index_state *, int);
int unmerge_index_entry(struct index_state *, const char *, struct resolve_undo_info *);
void unmerge_index(struct index_state *, const struct pathspec *);
void unmerge_marked_index(struct index_state *);