Warn on rustdoc::unescaped_backticks for core/alloc/std/test/proc_macro

They are all clean now, so enable the lint to keep them clean going forward.

Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

library/alloc/src/lib.rs

@@ -86,6 +86,7 @@
 #![warn(multiple_supertrait_upcastable)]
 #![allow(internal_features)]
 #![allow(rustdoc::redundant_explicit_links)]
+#![warn(rustdoc::unescaped_backticks)]
 #![deny(ffi_unwind_calls)]
 //
 // Library features:

library/core/src/lib.rs

@@ -103,6 +103,7 @@
 #![deny(ffi_unwind_calls)]
 // Do not check link redundancy on bootstraping phase
 #![allow(rustdoc::redundant_explicit_links)]
+#![warn(rustdoc::unescaped_backticks)]
 //
 // Library features:
 // tidy-alphabetical-start

library/proc_macro/src/lib.rs

@@ -37,6 +37,7 @@
 #![recursion_limit = "256"]
 #![allow(internal_features)]
 #![deny(ffi_unwind_calls)]
+#![warn(rustdoc::unescaped_backticks)]
 
 #[unstable(feature = "proc_macro_internals", issue = "27812")]
 #[doc(hidden)]

library/std/src/lib.rs

@@ -254,6 +254,7 @@
 #![deny(fuzzy_provenance_casts)]
 #![deny(unsafe_op_in_unsafe_fn)]
 #![allow(rustdoc::redundant_explicit_links)]
+#![warn(rustdoc::unescaped_backticks)]
 // Ensure that std can be linked against panic_abort despite compiled with `-C panic=unwind`
 #![deny(ffi_unwind_calls)]
 // std may use features in a platform-specific way

library/test/src/lib.rs

@@ -24,6 +24,7 @@
 #![feature(panic_can_unwind)]
 #![feature(test)]
 #![allow(internal_features)]
+#![warn(rustdoc::unescaped_backticks)]
 
 pub use self::bench::{black_box, Bencher};
 pub use self::console::run_tests_console;