diff options
Diffstat (limited to 'revision.c')
| -rw-r--r-- | revision.c | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/revision.c b/revision.c index 64b86ae91..62f399c22 100644 --- a/revision.c +++ b/revision.c @@ -2136,6 +2136,73 @@ static int mark_redundant_parents(struct rev_info *revs, struct commit *commit) return marked; } +/* + * Awkward naming - this means one parent we are TREESAME to. + * cf mark_treesame_root_parents: root parents that are TREESAME (to an + * empty tree). Better name suggestions? + */ +static int leave_one_treesame_to_parent(struct rev_info *revs, struct commit *commit) +{ + struct treesame_state *ts = lookup_decoration(&revs->treesame, &commit->object); + struct commit *unmarked = NULL, *marked = NULL; + struct commit_list *p; + unsigned n; + + for (p = commit->parents, n = 0; p; p = p->next, n++) { + if (ts->treesame[n]) { + if (p->item->object.flags & TMP_MARK) { + if (!marked) + marked = p->item; + } else { + if (!unmarked) { + unmarked = p->item; + break; + } + } + } + } + + /* + * If we are TREESAME to a marked-for-deletion parent, but not to any + * unmarked parents, unmark the first TREESAME parent. This is the + * parent that the default simplify_history==1 scan would have followed, + * and it doesn't make sense to omit that path when asking for a + * simplified full history. Retaining it improves the chances of + * understanding odd missed merges that took an old version of a file. + * + * Example: + * + * I--------*X A modified the file, but mainline merge X used + * \ / "-s ours", so took the version from I. X is + * `-*A--' TREESAME to I and !TREESAME to A. + * + * Default log from X would produce "I". Without this check, + * --full-history --simplify-merges would produce "I-A-X", showing + * the merge commit X and that it changed A, but not making clear that + * it had just taken the I version. With this check, the topology above + * is retained. + * + * Note that it is possible that the simplification chooses a different + * TREESAME parent from the default, in which case this test doesn't + * activate, and we _do_ drop the default parent. Example: + * + * I------X A modified the file, but it was reverted in B, + * \ / meaning mainline merge X is TREESAME to both + * *A-*B parents. + * + * Default log would produce "I" by following the first parent; + * --full-history --simplify-merges will produce "I-A-B". But this is a + * reasonable result - it presents a logical full history leading from + * I to X, and X is not an important merge. + */ + if (!unmarked && marked) { + marked->object.flags &= ~TMP_MARK; + return 1; + } + + return 0; +} + static int remove_marked_parents(struct rev_info *revs, struct commit *commit) { struct commit_list **pp, *p; @@ -2239,6 +2306,8 @@ static struct commit_list **simplify_one(struct rev_info *revs, struct commit *c if (1 < cnt) { int marked = mark_redundant_parents(revs, commit); if (marked) + marked -= leave_one_treesame_to_parent(revs, commit); + if (marked) cnt = remove_marked_parents(revs, commit); } |