clippy: Enable needless_doctest_main rule

Author: tetsuharuohzeki

Cargo.toml

@@ -170,7 +170,6 @@ useless_asref = "allow"
 ## Following lints should be tackled at some point
 borrowed_box = "allow"
 derived_hash_with_manual_eq = "allow"
-needless_doctest_main = "allow"
 too_many_arguments = "allow"
 type_complexity = "allow"
 wrong_self_convention = "allow"

crates/ide/src/inlay_hints/implicit_drop.rs

@@ -1,10 +1,8 @@
 //! Implementation of "implicit drop" inlay hints:
-//! ```no_run
-//! fn main() {
-//!     let x = vec![2];
-//!     if some_condition() {
-//!         /* drop(x) */return;
-//!     }
+//! ```ignore
+//! let x = vec![2];
+//! if some_condition() {
+//!     /* drop(x) */return;
 //! }
 //! ```
 use hir::{