Rollup merge of rust-lang#60521 - rasendubi:tidy-2018-edition, r=Centril

Migrate tidy to rust 2018 edition

cc @Centril

Author: Centril

Diff for: src/tools/tidy/Cargo.toml

@@ -2,6 +2,7 @@
 name = "tidy"
 version = "0.1.0"
 authors = ["Alex Crichton <alex@alexcrichton.com>"]
+edition = "2018"
 
 [dependencies]
 regex = "1"

Diff for: src/tools/tidy/src/deps.rs

@@ -5,6 +5,7 @@ use std::fs;
 use std::path::Path;
 use std::process::Command;
 
+use serde_derive::Deserialize;
 use serde_json;
 
 const LICENSES: &[&str] = &[

Diff for: src/tools/tidy/src/features.rs

@@ -18,7 +18,7 @@ use std::path::Path;
 use regex::{Regex, escape};
 
 mod version;
-use self::version::Version;
+use version::Version;
 
 const FEATURE_GROUP_START_PREFIX: &str = "// feature-group-start";
 const FEATURE_GROUP_END_PREFIX: &str = "// feature-group-end";

Diff for: src/tools/tidy/src/features/version.rs

@@ -31,15 +31,13 @@ impl FromStr for Version {
     fn from_str(s: &str) -> Result<Self, Self::Err> {
         let mut iter = s.split('.').map(|part| Ok(part.parse()?));
 
-        let parts = {
-            let mut part = || {
-                iter.next()
-                    .unwrap_or(Err(ParseVersionError::WrongNumberOfParts))
-            };
-
-            [part()?, part()?, part()?]
+        let mut part = || {
+            iter.next()
+                .unwrap_or(Err(ParseVersionError::WrongNumberOfParts))
         };
 
+        let parts = [part()?, part()?, part()?];
+
         if let Some(_) = iter.next() {
             // Ensure we don't have more than 3 parts.
             return Err(ParseVersionError::WrongNumberOfParts);

Diff for: src/tools/tidy/src/lib.rs

@@ -3,13 +3,6 @@
 //! This library contains the tidy lints and exposes it
 //! to be used by tools.
 
-#![deny(rust_2018_idioms)]
-
-extern crate regex;
-extern crate serde_json;
-#[macro_use]
-extern crate serde_derive;
-
 use std::fs;
 
 use std::path::Path;

Diff for: src/tools/tidy/src/main.rs

@@ -4,10 +4,8 @@
 //! etc. This is run by default on `make check` and as part of the auto
 //! builders.
 
-#![deny(rust_2018_idioms)]
 #![deny(warnings)]
 
-extern crate tidy;
 use tidy::*;
 
 use std::process;