[kbd]

> Then this PR was filed. Invalid user input should not be classed as undefined behavior and concluding that the standard library's UTF decoder shouldn't be used if you want a safe execution is just absurd.

Just to copy Andrew's final words in here:

> I think the entire std.unicode needs an audit both in terms of API design and performance. This module is not yet what it will become before stabilization. But this commit is not where this is going.

The PR wanted to make a function that takes runtime values only take comptime values. I read Andrew's response as saying "this all needs to be looked at before 1.0 but this isn't the way to fix this", which seems to me to be an entirely reasonable thing to reject a PR with.