Remove lib.register_* and src/docs* in cargo dev update_lints

Author: Alexendoo

clippy_dev/src/update_lints.rs

@@ -36,6 +36,57 @@ pub enum UpdateMode {
 pub fn update(update_mode: UpdateMode) {
     let (lints, deprecated_lints, renamed_lints) = gather_all();
     generate_lint_files(update_mode, &lints, &deprecated_lints, &renamed_lints);
+    remove_old_files(update_mode);
+}
+
+/// Remove files no longer needed after <https://github.com/rust-lang/rust-clippy/pull/9541>
+/// that may be reintroduced unintentionally
+fn remove_old_files(update_mode: UpdateMode) {
+    let mut failed = false;
+    let mut remove_file = |path: &Path| match update_mode {
+        UpdateMode::Check => {
+            if path.exists() {
+                failed = true;
+                println!("unexpected file: {}", path.display());
+            }
+        },
+        UpdateMode::Change => {
+            if fs::remove_file(path).is_ok() {
+                println!("removed file: {}", path.display());
+            }
+        },
+    };
+
+    let files = [
+        "clippy_lints/src/lib.register_all.rs",
+        "clippy_lints/src/lib.register_cargo.rs",
+        "clippy_lints/src/lib.register_complexity.rs",
+        "clippy_lints/src/lib.register_correctness.rs",
+        "clippy_lints/src/lib.register_internal.rs",
+        "clippy_lints/src/lib.register_lints.rs",
+        "clippy_lints/src/lib.register_nursery.rs",
+        "clippy_lints/src/lib.register_pedantic.rs",
+        "clippy_lints/src/lib.register_perf.rs",
+        "clippy_lints/src/lib.register_restriction.rs",
+        "clippy_lints/src/lib.register_style.rs",
+        "clippy_lints/src/lib.register_suspicious.rs",
+        "src/docs.rs",
+    ];
+
+    for file in files {
+        remove_file(Path::new(file));
+    }
+
+    if let Ok(docs_dir) = fs::read_dir("src/docs") {
+        for doc_file in docs_dir {
+            let path = doc_file.unwrap().path();
+            remove_file(&path);
+        }
+    }
+
+    if failed {
+        exit_with_failure();
+    }
 }
 
 fn generate_lint_files(