Update example code to 2018 edition

Author: dtolnay

.travis.yml

@@ -6,7 +6,7 @@ rust:
   - nightly
   - beta
   - stable
-  - 1.30.0
+  - 1.31.0
 
 script:
   - cargo run --manifest-path example/Cargo.toml
@@ -17,3 +17,7 @@ matrix:
       name: Minimal versions
       before_script:
         - cargo update -Z minimal-versions --manifest-path example/Cargo.toml
+    - rust: 1.30.0
+      name: 2015 edition
+      script:
+        - cargo check

README.md

@@ -32,9 +32,6 @@ macros.
 
 ```rust
 extern crate proc_macro;
-extern crate proc_macro_hack;
-extern crate quote;
-extern crate syn;
 
 use proc_macro::TokenStream;
 use proc_macro_hack::proc_macro_hack;
@@ -63,9 +60,6 @@ procedural macro from the implementation crate. The re-export also carries a
 \#\[proc_macro_hack\] attribute.
 
 ```rust
-extern crate demo_hack_impl;
-extern crate proc_macro_hack;
-
 use proc_macro_hack::proc_macro_hack;
 
 /// Add one to an expression.
@@ -96,7 +90,6 @@ implementation crate), then use your procedural macros as usual.
 [> example of a downstream crate][example]
 
 ```rust
-extern crate demo_hack;
 use demo_hack::add_one;
 
 fn main() {

demo-hack-impl/Cargo.toml

@@ -5,6 +5,7 @@ authors = ["David Tolnay <[email protected]>"]
 license = "MIT/Apache-2.0"
 description = "Demo of proc-macro-hack"
 repository = "https://github.com/dtolnay/proc-macro-hack"
+edition = "2018"
 
 [lib]
 proc-macro = true

demo-hack-impl/src/lib.rs

@@ -1,7 +1,4 @@
 extern crate proc_macro;
-extern crate proc_macro_hack;
-extern crate quote;
-extern crate syn;
 
 use proc_macro::TokenStream;
 use proc_macro_hack::proc_macro_hack;

demo-hack/Cargo.toml

@@ -5,6 +5,7 @@ authors = ["David Tolnay <[email protected]>"]
 license = "MIT/Apache-2.0"
 description = "Demo of proc-macro-hack"
 repository = "https://github.com/dtolnay/proc-macro-hack"
+edition = "2018"
 
 [dependencies]
 proc-macro-hack = { version = "0.5", path = ".." }

demo-hack/src/lib.rs

@@ -1,6 +1,3 @@
-extern crate demo_hack_impl;
-extern crate proc_macro_hack;
-
 use proc_macro_hack::proc_macro_hack;
 
 /// Add one to an expression.

example/Cargo.toml

@@ -2,6 +2,7 @@
 name = "example"
 version = "0.0.0"
 authors = ["David Tolnay <[email protected]>"]
+edition = "2018"
 publish = false
 
 [dependencies]

example/src/main.rs

@@ -1,4 +1,3 @@
-extern crate demo_hack;
 use demo_hack::add_one;
 
 fn main() {

nested/src/lib.rs

@@ -22,8 +22,6 @@
 //! ```rust
 //! // After
 //! # const IGNORE: &str = stringify! {
-//! extern crate proc_macro_nested;
-//!
 //! #[proc_macro_hack(support_nested)]
 //! pub use demo_hack_impl::add_one;
 //! # }

src/lib.rs

@@ -24,9 +24,6 @@
 //!
 //! ```rust
 //! extern crate proc_macro;
-//! extern crate proc_macro_hack;
-//! extern crate quote;
-//! extern crate syn;
 //!
 //! use proc_macro::TokenStream;
 //! use proc_macro_hack::proc_macro_hack;
@@ -59,9 +56,6 @@
 //! \#\[proc_macro_hack\] attribute.
 //!
 //! ```rust
-//! extern crate demo_hack_impl;
-//! extern crate proc_macro_hack;
-//!
 //! use proc_macro_hack::proc_macro_hack;
 //!
 //! /// Add one to an expression.
@@ -94,7 +88,6 @@
 //! [> example of a downstream crate][example]
 //!
 //! ```rust
-//! extern crate demo_hack;
 //! use demo_hack::add_one;
 //!
 //! fn main() {