This is helpful when examining branches with disjoint roots, for example because one is periodically merged into a subtree of the other.
With the --merge-child option, "git merge-base" will print a first-parent ancestor of the first revision given, where the commit printed is either a merge-base of the supplied revisions or a merge for which one of its parents (not the first) is a merge-base. For example, given the history: A---C---G \ B-----D---F \ E we have: $ git merge-base F E B $ git merge-base --merge-child F E D $ git merge-base F G C $ git merge-base --merge-child F G C $ git log --left-right F...E < F < D < C < A > E $ git log --left-right F...E --not $(git merge-base --merge-child F E) < F > E The git-log case is useful because it allows us to limit the range of commits that we are examining for patch-identical changes when using --cherry. For example with git-gui in git.git I know that anything before the last merge of git-gui is not interesting: $ time git log --cherry master...git-gui/master >/dev/null real 0m32.731s user 0m31.956s sys 0m0.664s $ time git log --cherry master...git-gui/master --not \ $(git merge-base --merge-child master git-gui/master) \ >/dev/null real 0m2.296s user 0m2.193s sys 0m0.092s The first commit is a small prerequisite to extract a useful function from builtin/tag.c to commit.c. The second is the main change (the commit message is identical to the text before this paragraph). I'm not convinced that '--merge-child' is the right name for this but I think the functionality itself is useful. John Keeping (2): commit: add commit_list_contains function merge-base: add --merge-child option Documentation/git-merge-base.txt | 6 ++++ builtin/merge-base.c | 61 ++++++++++++++++++++++++++++++++++++++-- builtin/tag.c | 10 +------ commit.c | 8 ++++++ commit.h | 1 + t/t6010-merge-base.sh | 25 ++++++++++++++-- 6 files changed, 98 insertions(+), 13 deletions(-) -- 1.8.3.rc1.289.gcb3647f -- To unsubscribe from this list: send the line "unsubscribe git" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html