Enable diffing two arbitrary files in a PR?

[forevermatt]

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It seems like it would be helpful to be able to see a diff of two arbitrary files in a Pull Request.

Given the various discussions of times when either git or GitHub doesn't seem to recognize that a file was moved/renamed (and instead shows it as a deleted file and unrelated new file), the ability to arbitrarily select two files in a PR and see a diff of them seems like it would be quite helpful in many situations.

There are even times (such as when changing CI/CD systems) that genuinely separate files will have meaningfully similar/related content, and seeing a diff of them would help the reviewer see what was changed (e.g. in the move from an old CI/CD system to a new one).

Thoughts?

(P.S. Is this the right place to request this as a feature in GitHub?)