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Date:   Wed, 2 Jun 2021 15:29:44 +0000
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc:     git@vger.kernel.org, Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Jiri Kosina <trivial@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: git feature request: git blame --ignore-cleanup/--ignore-trivial
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On Wed, Jun 02, 2021 at 11:20:35AM -0400, Mathieu Desnoyers wrote:
> Hi,
> 
> Following a discussion with Peter Zijlstra about whether code cleanup
> and functional changes done to the Linux kernel scheduler belong to separate
> patches or should be folded together, the argument for folding cleanup
> and function changes came to be mainly motivated by the current behavior
> of git blame: code cleanup patches end up burying the important changes so
> it becomes cumbersome to find them using git blame.
> 
> Considering the added value brought by splitting cleanups from functional changes
> from a maintainer perspective (easier reverts) and from a reviewer perspective
> (easier to focus on the functional changes), I think it would be good to improve
> the git tooling to allow easily filtering out the noise from git blame.
> 
> Perhaps a new git blame "--ignore-trivial" and/or "--ignore-cleanup" could solve
> this by filtering out "trivial" and "cleanup" patches from the history it considers.
> 
> Tagging patches as trivial and cleanup should be done in the patch commit message
> (possibly in the title), and enforcing proper tagging of commits is already the
> responsibility of the maintainer merging those cleanup/trivial commits into the
> Linux kernel anyway.
> 
> Under the hood, I suspect it could use something similar to git log --grep=<pattern>
> --invert-grep.
> 
> This should allow git blame users to easily filter out the noise and focus on the relevant
> functional changes.
> 
> Any maybe the patterns associated to "cleanup" and "trivial" commits should be something
> that can be configured through a git config file.
> 
> Thoughts ?

Just an observation: quite a few subtle bugs arise from mistakes in
what should've been a trivial cleanup.  Hell, I've seen bugs coming
from rebase of provably no-op patches - with commit message unchanged.
So IME this is counterproductive...