Rollup merge of #77739 - est31:remove_unused_code, r=petrochenkov,varkor

Remove unused code

Rustc has a builtin lint for detecting unused code inside a crate, but when an item is marked `pub`, the code, even if unused inside the entire workspace, is never marked as such. Therefore, I've built [warnalyzer](https://github.com/est31/warnalyzer) to detect unused items in a cross-crate setting.

Closes https://github.com/est31/warnalyzer/issues/2

diff --cc compiler/rustc_ast/src/token.rs
Simple merge

diff --cc compiler/rustc_codegen_ssa/src/back/write.rs
Simple merge

diff --cc compiler/rustc_hir_pretty/src/lib.rs
Simple merge

diff --cc compiler/rustc_parse/src/lib.rs
Simple merge