Re: [PATCH] Create '--merges-only' option for 'git bisect'

From: Stefan Beller <sbeller@google.com>
Date: Apr 11, 2018, 23:33 UTC
Message-ID: <CAGZ79kbt=J5SHsHJTfOZYhgSdn9_gOjVBC3qp_oL0sC-b3ZRmw@mail.gmail.com>
In-Reply-To: <20180411225534.48658-1-haraldnordgren@gmail.com>

On Wed, Apr 11, 2018 at 3:55 PM, Harald Nordgren <haraldnordgren@gmail.com> wrote:

> When ran with '--merges-only', git bisect will only look at merge commits -- commits with 2 or more parents or the initial commit.

There has been quite some talk on the mailing list, e.g. https://public-inbox.org/git/20160427204551.GB4613@virgo.localdomain/ which suggests a --first-parent mode instead. For certain histories these are the same, but merges-only is more restrictive for back-and-forth-cross merges.

Show 6 quoted lines

>
> Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
> ---
>
> Notes:
>     Proof of concept of a feature that I have wanted in Git for a while. In my daily work my company uses GitHub, which creates lots of merge commits. In general, tests are only ran on the tip of a branch before merging, so the different commits within a merge commit are allowed not to be buildable. Therefore 'git bisect' often doesn't work since it will give lots of false positives for anything that is not a merge commit. If we could have a feature to only bisect merge commits then it would be easier to pinpoint which merge causes any particular issue. After that, a bisect could be done within the merge to pinpoint futher. As a follow-up to this patch -- we could potentially create a feature that automatically continues into regular bisect within the bad merge commit after completed '--merges-only' bisection.

The github workflow you mention sounds as if --first-parent would do, too?