Rollup of 6 pull requests#91788

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matthiaskrgr wants to merge 15 commits into

rust-lang:masterfrom

matthiaskrgr:rollup-9ng4uzo

Commits on Dec 8, 2021

Use spare_capacity_mut instead of invalid unchecked indexing
saethlin
committed

Commits on Dec 9, 2021

rustdoc: Show type layout for type aliases
camelid
committed
Improve the readability of `List<T>`.
nnethercote
committed
Improve std::iter::zip example.

Andrew Banchich
and
r00ster
committed

Commits on Dec 10, 2021

asm: Allow using r9 (ARM) and x18 (AArch64) if they are not reserved by
Amanieu
committed

Commits on Dec 11, 2021