From 0b10b8a3d53c7aaf42b8f14da1021ea59ea4e0ec Mon Sep 17 00:00:00 2001 From: Junio C Hamano Date: Sat, 25 Apr 2015 10:25:43 -0700 Subject: [PATCH] merge: clarify collect_parents() logic Clarify this small function in three ways. - The function initially collects all commits to be merged into a commit_list "remoteheads"; the "remotes" pointer always points at the tail of this list (either the remoteheads variable itself, or the ->next slot of the element at the end of the list) to help elongate the list by repeated calls to commit_list_insert(). Because the new element appended by commit_list_insert() will always have its ->next slot NULLed out, there is no need for us to assign NULL to *remotes to terminate the list at the end. - The variable "head_subsumed" always confused me every time I read this code. What is happening here is that we inspect what the caller told us to merge (including the current HEAD) and come up with the list of parents to be recorded for the resulting merge commit, omitting commits that are ancestor of other commits. This filtering may remove the current HEAD from the resulting parent list---and we signal that fact with this variable, so that we can later record it as the first parent when "--no-ff" is in effect. - The "parents" list is created for this function by reduce_heads() and was not deallocated after its use, even though the loop control was written in such a way to allow us to do so by taking the "next" element in a separate variable so that it can be used in the next-step part of the loop control. Signed-off-by: Junio C Hamano --- builtin/merge.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/builtin/merge.c b/builtin/merge.c index b2d03323cb..d2e36e2051 100644 --- a/builtin/merge.c +++ b/builtin/merge.c @@ -1061,11 +1061,19 @@ static struct commit_list *collect_parents(struct commit *head_commit, "not something we can merge"); remotes = &commit_list_insert(commit, remotes)->next; } - *remotes = NULL; + /* + * Is the current HEAD reachable from another commit being + * merged? If so we do not want to record it as a parent of + * the resulting merge, unless --no-ff is given. We will flip + * this variable to 0 when we find HEAD among the independent + * tips being merged. + */ + *head_subsumed = 1; + + /* Find what parents to record by checking independent ones. */ parents = reduce_heads(remoteheads); - *head_subsumed = 1; /* we will flip this to 0 when we find it */ for (remoteheads = NULL, remotes = &remoteheads; parents; parents = next) { @@ -1075,6 +1083,7 @@ static struct commit_list *collect_parents(struct commit *head_commit, *head_subsumed = 0; else remotes = &commit_list_insert(commit, remotes)->next; + free(parents); } return remoteheads; } -- 2.11.4.GIT