Rollup merge of #152164 - mu001999-contrib:lint/unused_features, r=JonathanBrouwer

Lint unused features

*[View all comments](https://triagebot.infra.rust-lang.org/gh-comments/rust-lang/rust/pull/152164)*

Fixes rust-lang/rust#44232
Fixes rust-lang/rust#151752

---

This PR records used features through query side effect, then reports unsued features finally.

crates/proc-macro-api/src/lib.rs

@@ -10,7 +10,7 @@
     feature = "sysroot-abi",
     feature(proc_macro_internals, proc_macro_diagnostic, proc_macro_span)
 )]
-#![allow(internal_features)]
+#![allow(internal_features, unused_features)]
 #![cfg_attr(feature = "in-rust-tree", feature(rustc_private))]
 
 #[cfg(feature = "in-rust-tree")]

crates/proc-macro-srv/src/lib.rs

@@ -18,7 +18,8 @@
     internal_features,
     clippy::disallowed_types,
     clippy::print_stderr,
-    unused_crate_dependencies
+    unused_crate_dependencies,
+    unused_features
 )]
 #![deny(deprecated_safe, clippy::undocumented_unsafe_blocks)]