[Merged by Bors] - chore: add missing hypothesis names to by_cases

[Ruben-VandeVelde]

I've also got a change to make this required, but I'd like to land this first.

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[alexjbest]

Sorry but why do we want to make this required?

[Ruben-VandeVelde]

Lean 4 generally leans towards not introducing accessible names implicitly, and in fact doesn't introduce one in core by_cases; this only works because mathlib overrides the core implementation to expose it. This is inconsistent with most (all?) other tactics.

Of course, this PR is only desirable if the maintainers agree with that view; I'm not claiming that to be the case a priori (though I hope it is).

[alexjbest]

I certainly agree that implicitly introducing accessible names is a bug that should be fixed, I just missed the first time I looked the fact that in all your examples h is already used by name! Thanks!

maintainer merge

[alexjbest]

maintainer merge

[github-actions]

🚀 Pull request has been placed on the maintainer queue by alexjbest.

[kmill]

Thanks!

bors r+

[mathlib-bors]

Pull request successfully merged into master.

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