Rollup merge of #88492 - est31:maybe_uninit_write, r=wesleywiser
Rollup merge of #88492 - est31:maybe_uninit_write, r=wesleywiser

Use MaybeUninit::write in functor.rs

MaybeUninit::write is stable as of 1.55.0.

graydon/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,aidancully/rust,graydon/rust