Github panic early when `TrustedLen` indicates a `length > usize::MAX` by the...
source link: https://github.com/rust-lang/rust/pull/83726
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Changes TrustedLen specializations to immediately panic when size_hint().1 == None.
As far as I can tell this is not a change a minimal change in observable behavior for anything except ZSTs because the fallback path would go through extend_desugared() which tries to reserve(lower_bound) which already is usize::MAX and that would also lead to a panic. Before it might have popped somewhere between zero and a few elements from the iterator before panicking while it now panics immediately.
Overall this should reduce codegen by eliminating the fallback paths.
While looking into the with_capacity() behavior I also noticed that its documentation didn't have a Panics section, so I added that.
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