Re: [RFC PATCH 6/6] hex: allow only lowercase object IDs in breaking changes mode

From

Elijah Newren <newren@gmail.com>

Date

Aug 25, 2026, 19:44 UTC

Message-ID

<CABPp-BEAx+YZ547ig52EQaB65Yg6aEXb0qdLsWsChekhacqCSw@mail.gmail.com>

In-Reply-To

<20260729233215.398654-7-sandals@crustytoothpaste.net>

>
> In preparation for Git 3.0, only allow lowercase hex object IDs in
> breaking changes mode and document this as well.  Update the single
> failing test and add a new one to verify we reject new uppercase object
> IDs.  Note that in t5324, we change the hex character from "A" to "b"
> because in SHA-256 mode, "a" is the correct value, so our test_must_fail
> assertion will unexpectedly succeed in that case.

[...snip...]

> -               corrupt_file "$graphdir/commit-graph-chain" 30 "A" &&
> +               corrupt_file "$graphdir/commit-graph-chain" 30 "a" &&

[...]

> -               corrupt_file "$graphdir/commit-graph-chain" 70 "A" &&
> +               corrupt_file "$graphdir/commit-graph-chain" 70 "b" &&

which "A" is the commit message referring to?

> +* Git will accept hex object IDs only in lowercase. The fact that Git has
> +       historically allowed uppercase characters in hex object IDs has been the
> +       source of a variety of bugs and security problems in software using Git. We
> +       don't expect most users to notice any change.