disallow Rust 2018 idioms for clearer code

Author: Byron

Cargo.toml

@@ -12,8 +12,7 @@ readme = "changelog.md"
 include = ["src/**/*", "LICENSE.md", "README.md", "CHANGELOG.md"]
 
 [dependencies]
-serde = "1"
-serde_derive = "1"
+serde = { version = "1", features = ["std", "derive"] }
 serde_json = "1"
 
 [dependencies.git2]

src/index.rs

@@ -45,7 +45,7 @@ impl Index {
     }
 
     /// Return the reference pointing to the state we have seen after calling `fetch_changes()`.
-    pub fn last_seen_reference(&self) -> Result<Reference, GitError> {
+    pub fn last_seen_reference(&self) -> Result<Reference<'_>, GitError> {
         self.repo.find_reference(self.seen_ref_name)
     }
 
@@ -104,7 +104,7 @@ impl Index {
         CloneOptions {
             repository_url,
             fetch_options,
-        }: CloneOptions,
+        }: CloneOptions<'_>,
     ) -> Result<Index, GitError> {
         let mut repo_did_exist = true;
         let repo = Repository::open(path.as_ref()).or_else(|err| {
@@ -265,10 +265,10 @@ impl Index {
     /// to either `Commit`s or `Tree`s.
     pub fn changes_from_objects(
         &self,
-        from: &Object,
-        to: &Object,
+        from: &Object<'_>,
+        to: &Object<'_>,
     ) -> Result<Vec<Change>, GitError> {
-        fn into_tree<'a>(repo: &'a Repository, obj: &Object) -> Result<Tree<'a>, GitError> {
+        fn into_tree<'a>(repo: &'a Repository, obj: &Object<'_>) -> Result<Tree<'a>, GitError> {
             repo.find_tree(match obj.kind() {
                 Some(ObjectType::Commit) => obj
                     .as_commit()

src/lib.rs

@@ -3,8 +3,7 @@
 //! Have a look at the real-world usage to learn more about it:
 //! [crates-io-cli](https://github.com/Byron/crates-io-cli-rs/blob/b7a39ad8ef68adb81b2d8a7e552cb0a2a73f7d5b/src/main.rs#L62)
 #![forbid(missing_docs)]
-#[macro_use]
-extern crate serde_derive;
+#![deny(rust_2018_idioms)]
 
 mod index;
 mod version;

src/version.rs

@@ -14,7 +14,7 @@ pub enum Change {
 }
 
 impl fmt::Display for Change {
-    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         write!(
             f,
             "{}",
@@ -28,7 +28,7 @@ impl fmt::Display for Change {
 }
 
 /// Pack all information we know about a change made to a version of a crate.
-#[derive(Clone, Serialize, Deserialize, Eq, PartialEq, Debug)]
+#[derive(Clone, serde::Serialize, serde::Deserialize, Eq, PartialEq, Debug)]
 pub struct CrateVersion {
     /// The crate name, i.e. `clap`.
     pub name: String,
@@ -48,7 +48,7 @@ pub struct CrateVersion {
 }
 
 /// A single dependency of a specific crate version
-#[derive(Clone, Serialize, Deserialize, Ord, PartialOrd, Eq, PartialEq, Debug)]
+#[derive(Clone, serde::Serialize, serde::Deserialize, Ord, PartialOrd, Eq, PartialEq, Debug)]
 pub struct Dependency {
     /// The crate name
     pub name: String,