Simplify and fix --first-parent implementation

The purpose of --first-parent is to view the tree without looking at
side branche.  This is accomplished by pretending there are no other
parents than the first parent when encountering a merge.

The current code marks the other parents as seen, which means that the tree
traversal will behave differently depending on the order merges are handled.

When a fast forward is artificially recorded as a merge,

       -----
      /     \
 D---E---F---G master

the 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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/revision.c b/revision.c
index 4231ea2cce57c74a4110c9c69459a4caf67dc15c..bcfcd2a82bb06cd565cf5d20fea3fc0a25da2242 100644 (file)
--- 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;
 }