Stephen R. van den BergThe purpose of --first-parent is to simplify the tree into a tree without merges. This is accomplished by pretending there are no other parents than the first parent when encountering a merge. In order to implement this correctly the behaviour should be such that the tree traversal does not depend on any parent other than the first.
The old code marked the other parents as seen, which means that the tree traversal (under certain circumstances) will behave differently depending on which merges have been done, therefore violating the rule that only the first parent should be relevant.
Case in point, given the following tree:
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/ \
D---E---F---G masterThe current first-parent code considers E to be seen and stops the traversal after showing G and F.
Signed-off-by: Stephen R. van den Berg <srb@cuci.nl> ---
revision.c | 10 ++++------ 1 files changed, 4 insertions(+), 6 deletions(-)
Show changes to revision.c +4 −6
diff --git a/revision.c b/revision.c index 4231ea2..bcfcd2a 100644 --- a/revision.c +++ b/revision.c @@ -415,7 +415,6 @@ static int add_parents_to_list(struct rev_info *revs, struct commit *commit, str { struct commit_list *parent = commit->parents; unsigned left_flag; - int add, rest; if (commit->object.flags & ADDED) return 0; @@ -462,19 +461,18 @@ static int add_parents_to_list(struct rev_info *revs, struct commit *commit, str left_flag = (commit->object.flags & SYMMETRIC_LEFT); - rest = !revs->first_parent_only; - for (parent = commit->parents, add = 1; parent; add = rest) { + for (parent = commit->parents; parent; parent = parent->next) { struct commit *p = parent->item; - parent = parent->next; if (parse_commit(p) < 0) return -1; p->object.flags |= left_flag; if (p->object.flags & SEEN) continue; p->object.flags |= SEEN; - if (add) - insert_by_date(p, list); + insert_by_date(p, list); + if(revs->first_parent_only) + break; } return 0; }