Migrate all crates to the 2018 edition

Most of the CLI crates were already in the 2018 edition, and it turns
out that one of the macro crates was already in the 2018 edition so we
may as well move everything to the 2018 edition!

Always nice to remove those `extern crate` statements nowadays!

This commit also does a `cargo fmt --all` to make sure we're conforming
with style again.

crates/backend/src/encode.rs

@@ -1,13 +1,13 @@
+use crate::util::ShortHash;
 use proc_macro2::{Ident, Span};
-use std::cell::{RefCell, Cell};
+use std::cell::{Cell, RefCell};
 use std::collections::HashMap;
 use std::env;
 use std::fs;
 use std::path::PathBuf;
-use util::ShortHash;
 
-use ast;
-use Diagnostic;
+use crate::ast;
+use crate::Diagnostic;
 
 pub struct EncodeResult {
     pub custom_section: Vec<u8>,
@@ -19,8 +19,17 @@ pub fn encode(program: &ast::Program) -> Result<EncodeResult, Diagnostic> {
     let i = Interner::new();
     shared_program(program, &i)?.encode(&mut e);
     let custom_section = e.finish();
-    let included_files = i.files.borrow().values().map(|p| &p.path).cloned().collect();
-    Ok(EncodeResult { custom_section, included_files })
+    let included_files = i
+        .files
+        .borrow()
+        .values()
+        .map(|p| &p.path)
+        .cloned()
+        .collect();
+    Ok(EncodeResult {
+        custom_section,
+        included_files,
+    })
 }
 
 struct Interner {
@@ -67,16 +76,16 @@ impl Interner {
     fn resolve_import_module(&self, id: &str, span: Span) -> Result<&str, Diagnostic> {
         let mut files = self.files.borrow_mut();
         if let Some(file) = files.get(id) {
-            return Ok(self.intern_str(&file.new_identifier))
+            return Ok(self.intern_str(&file.new_identifier));
         }
         self.check_for_package_json();
         let path = if id.starts_with("/") {
             self.root.join(&id[1..])
         } else if id.starts_with("./") || id.starts_with("../") {
             let msg = "relative module paths aren't supported yet";
-            return Err(Diagnostic::span_error(span, msg))
+            return Err(Diagnostic::span_error(span, msg));
         } else {
-            return Ok(self.intern_str(&id))
+            return Ok(self.intern_str(&id));
         };
 
         // Generate a unique ID which is somewhat readable as well, so mix in
@@ -98,7 +107,7 @@ impl Interner {
 
     fn check_for_package_json(&self) {
         if self.has_package_json.get() {
-            return
+            return;
         }
         let path = self.root.join("package.json");
         if path.exists() {
@@ -139,11 +148,9 @@ fn shared_program<'a>(
             .values()
             .map(|file| {
                 fs::read_to_string(&file.path)
-                    .map(|s| {
-                        LocalModule {
-                            identifier: intern.intern_str(&file.new_identifier),
-                            contents: intern.intern_str(&s),
-                        }
+                    .map(|s| LocalModule {
+                        identifier: intern.intern_str(&file.new_identifier),
+                        contents: intern.intern_str(&s),
                     })
                     .map_err(|e| {
                         let msg = format!("failed to read file `{}`: {}", file.path.display(), e);
@@ -499,4 +506,4 @@ macro_rules! encode_api {
         encode_api!($($rest)*);
     );
 }
-shared_api!(encode_api);
+wasm_bindgen_shared::shared_api!(encode_api);