Fix edition 2018 idioms (#93)

* Fix edition 2018 idioms
* Remove deprecated clippy plugin

README.md

@@ -2,9 +2,6 @@
 A cron expression parser. Works with stable Rust v1.28.0.
 
 ```rust
-extern crate cron;
-extern crate chrono;
-
 use cron::Schedule;
 use chrono::Utc;
 use std::str::FromStr;

src/error.rs

@@ -11,7 +11,7 @@ pub enum ErrorKind {
 }
 
 impl fmt::Display for Error {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self.kind {
             ErrorKind::Expression(ref expr) => write!(f, "Invalid expression: {}", expr),
         }

src/lib.rs

@@ -1,12 +1,8 @@
-#![cfg_attr(feature = "clippy", feature(plugin))]
-#![cfg_attr(feature = "clippy", plugin(clippy))]
+#![deny(rust_2018_idioms)]
 
 //! A cron expression parser and schedule explorer
 //! # Example
 //! ```
-//! extern crate chrono;
-//! extern crate cron;
-//!
 //! use cron::Schedule;
 //! use chrono::Utc;
 //! use std::str::FromStr;
@@ -36,9 +32,6 @@
 //! */
 //! ```
 
-#[cfg(test)]
-extern crate chrono_tz;
-
 pub mod error;
 mod schedule;
 mod time_unit;

src/schedule.rs

@@ -219,15 +219,15 @@ impl Schedule {
 
     /// Provides an iterator which will return each DateTime that matches the schedule starting with
     /// the current time if applicable.
-    pub fn upcoming<Z>(&self, timezone: Z) -> ScheduleIterator<Z>
+    pub fn upcoming<Z>(&self, timezone: Z) -> ScheduleIterator<'_, Z>
     where
         Z: TimeZone,
     {
         self.after(&timezone.from_utc_datetime(&Utc::now().naive_utc()))
     }
 
     /// Like the `upcoming` method, but allows you to specify a start time other than the present.
-    pub fn after<Z>(&self, after: &DateTime<Z>) -> ScheduleIterator<Z>
+    pub fn after<Z>(&self, after: &DateTime<Z>) -> ScheduleIterator<'_, Z>
     where
         Z: TimeZone,
     {
@@ -295,7 +295,7 @@ impl Schedule {
 }
 
 impl Display for Schedule {
-    fn fmt(&self, f: &mut Formatter) -> FmtResult {
+    fn fmt(&self, f: &mut Formatter<'_>) -> FmtResult {
         write!(f, "{}", self.source)
     }
 }

src/time_unit/mod.rs

@@ -123,7 +123,7 @@ pub trait TimeUnitSpec {
     /// assert_eq!(Some(8), summer.next());
     /// assert_eq!(None, summer.next());
     /// ```
-    fn iter(&self) -> OrdinalIter;
+    fn iter(&self) -> OrdinalIter<'_>;
 
     /// Provides an iterator which will return each included ordinal within the specified range.
     /// # Example
@@ -140,7 +140,7 @@ pub trait TimeUnitSpec {
     /// assert_eq!(Some(15), mid_month_paydays.next());
     /// assert_eq!(None, mid_month_paydays.next());
     /// ```
-    fn range<R>(&self, range: R) -> OrdinalRangeIter
+    fn range<R>(&self, range: R) -> OrdinalRangeIter<'_>
     where
         R: RangeBounds<Ordinal>;
 
@@ -179,7 +179,7 @@ where
     fn includes(&self, ordinal: Ordinal) -> bool {
         self.ordinals().contains(&ordinal)
     }
-    fn iter(&self) -> OrdinalIter {
+    fn iter(&self) -> OrdinalIter<'_> {
         OrdinalIter {
             set_iter: TimeUnitField::ordinals(self).iter(),
         }

tests/lib.rs

@@ -1,7 +1,3 @@
-extern crate chrono;
-extern crate chrono_tz;
-extern crate cron;
-
 #[cfg(test)]
 mod tests {
     use chrono::*;