diff --git a/juniper/src/macros/interface.rs b/juniper/src/macros/interface.rs
index e9b4a8b9..b0c6fa4a 100644
--- a/juniper/src/macros/interface.rs
+++ b/juniper/src/macros/interface.rs
@@ -190,7 +190,7 @@ macro_rules! graphql_interface {
                 ) -> $crate::ExecutionResult<$crate::__juniper_insert_generic!($($scalar)+)> {
                     $(
                         if field == &$crate::to_camel_case(stringify!($fn_name)) {
-                            let result: $return_ty = (|| {
+                            let f = (|| {
                                 $(
                                     let $arg_name: $arg_ty = args.get(&$crate::to_camel_case(stringify!($arg_name)))
                                         .expect(concat!(
@@ -203,7 +203,8 @@ macro_rules! graphql_interface {
                                     let $executor = &executor;
                                 )*
                                 $body
-                            })();
+                            });
+                            let result: $return_ty = f();
 
                             return $crate::IntoResolvable::into(result, executor.context())
                                 .and_then(|res| {
diff --git a/juniper/src/tests/model.rs b/juniper/src/tests/model.rs
index 509b8a4d..8731614b 100644
--- a/juniper/src/tests/model.rs
+++ b/juniper/src/tests/model.rs
@@ -100,6 +100,7 @@ impl Droid for DroidData {
     }
 }
 
+#[derive(Default)]
 pub struct Database {
     humans: HashMap<String, HumanData>,
     droids: HashMap<String, DroidData>,
@@ -122,7 +123,7 @@ impl HumanData {
                 .into_iter()
                 .map(|f| f.to_owned())
                 .collect(),
-            appears_in: appears_in.iter().cloned().collect(),
+            appears_in: appears_in.to_vec(),
             secret_backstory: secret_backstory.map(|b| b.to_owned()),
             home_planet: home_planet.map(|p| p.to_owned()),
         }
@@ -146,7 +147,7 @@ impl DroidData {
                 .into_iter()
                 .map(|f| f.to_owned())
                 .collect(),
-            appears_in: appears_in.iter().cloned().collect(),
+            appears_in: appears_in.to_vec(),
             secret_backstory: secret_backstory.map(|b| b.to_owned()),
             primary_function: primary_function.map(|p| p.to_owned()),
         }
diff --git a/juniper/src/util.rs b/juniper/src/util.rs
index c2b49a84..ccf7a16e 100644
--- a/juniper/src/util.rs
+++ b/juniper/src/util.rs
@@ -4,7 +4,7 @@ use std::borrow::Cow;
 ///
 /// Note: needs to be public because several macros use it.
 #[doc(hidden)]
-pub fn to_camel_case<'a>(s: &'a str) -> Cow<'a, str> {
+pub fn to_camel_case<'a>(s: &'a str) -> Cow<'_, str> {
     let mut dest = Cow::Borrowed(s);
 
     for (i, part) in s.split('_').enumerate() {
diff --git a/juniper/src/value/scalar.rs b/juniper/src/value/scalar.rs
index 60186e45..89b4276d 100644
--- a/juniper/src/value/scalar.rs
+++ b/juniper/src/value/scalar.rs
@@ -9,7 +9,7 @@ pub type ParseScalarResult<'a, S = DefaultScalarValue> = Result<S, ParseError<'a
 /// A trait used to convert a `ScalarToken` into a certain scalar value type
 pub trait ParseScalarValue<S = DefaultScalarValue> {
     /// See the trait documentation
-    fn from_str<'a>(value: ScalarToken<'a>) -> ParseScalarResult<'a, S>;
+    fn from_str(value: ScalarToken<'_>) -> ParseScalarResult<'_, S>;
 }
 
 /// A trait marking a type that could be used as internal representation of
diff --git a/juniper_codegen/src/lib.rs b/juniper_codegen/src/lib.rs
index 4c0cc951..79e7cda0 100644
--- a/juniper_codegen/src/lib.rs
+++ b/juniper_codegen/src/lib.rs
@@ -382,20 +382,18 @@ pub fn graphql_object_internal(args: TokenStream, input: TokenStream) -> TokenSt
 #[proc_macro_attribute]
 #[proc_macro_error::proc_macro_error]
 pub fn graphql_union(attrs: TokenStream, body: TokenStream) -> TokenStream {
-    let output = match impl_union::impl_union(false, attrs, body) {
+    match impl_union::impl_union(false, attrs, body) {
         Ok(toks) => toks,
         Err(err) => proc_macro_error::abort!(err),
-    };
-    output
+    }
 }
 
 #[doc(hidden)]
 #[proc_macro_attribute]
 #[proc_macro_error::proc_macro_error]
 pub fn graphql_union_internal(attrs: TokenStream, body: TokenStream) -> TokenStream {
-    let output = match impl_union::impl_union(true, attrs, body) {
+    match impl_union::impl_union(true, attrs, body) {
         Ok(toks) => toks,
         Err(err) => proc_macro_error::abort!(err),
-    };
-    output
+    }
 }
diff --git a/juniper_codegen/src/util/mod.rs b/juniper_codegen/src/util/mod.rs
index 57d3a7aa..f32aec29 100644
--- a/juniper_codegen/src/util/mod.rs
+++ b/juniper_codegen/src/util/mod.rs
@@ -20,7 +20,7 @@ pub fn name_of_type(ty: &syn::Type) -> Option<syn::Ident> {
         syn::Type::Reference(ref reference) => match &*reference.elem {
             syn::Type::Path(ref type_path) => Some(&type_path.path),
             syn::Type::TraitObject(ref trait_obj) => {
-                match trait_obj.bounds.iter().nth(0).unwrap() {
+                match trait_obj.bounds.iter().next().unwrap() {
                     syn::TypeParamBound::Trait(ref trait_bound) => Some(&trait_bound.path),
                     _ => None,
                 }
@@ -106,25 +106,22 @@ pub fn get_deprecated(attrs: &[Attribute]) -> Option<DeprecationAttr> {
 
 fn get_deprecated_meta_list(list: &MetaList) -> DeprecationAttr {
     for meta in &list.nested {
-        match meta {
-            &NestedMeta::Meta(Meta::NameValue(ref nv)) => {
-                if nv.path.is_ident("note") {
-                    match &nv.lit {
-                        &Lit::Str(ref strlit) => {
-                            return DeprecationAttr {
-                                reason: Some(strlit.value()),
-                            };
-                        }
-                        _ => panic!("deprecated attribute note value only has string literal"),
+        if let NestedMeta::Meta(Meta::NameValue(ref nv)) = *meta {
+            if nv.path.is_ident("note") {
+                match nv.lit {
+                    Lit::Str(ref strlit) => {
+                        return DeprecationAttr {
+                            reason: Some(strlit.value()),
+                        };
                     }
-                } else {
-                    panic!(
-                        "Unrecognized setting on #[deprecated(..)] attribute: {:?}",
-                        nv.path,
-                    );
+                    _ => panic!("deprecated attribute note value only has string literal"),
                 }
+            } else {
+                panic!(
+                    "Unrecognized setting on #[deprecated(..)] attribute: {:?}",
+                    nv.path,
+                );
             }
-            _ => {}
         }
     }
     DeprecationAttr { reason: None }
@@ -141,10 +138,10 @@ pub fn get_doc_comment(attrs: &[Attribute]) -> Option<String> {
 }
 
 // Concatenates doc strings into one string.
-fn join_doc_strings(docs: &Vec<String>) -> String {
+fn join_doc_strings(docs: &[String]) -> String {
     // Note: this is guaranteed since this function is only called
     // from get_doc_strings().
-    debug_assert!(docs.len() > 0);
+    debug_assert!(!docs.is_empty());
 
     let last_index = docs.len() - 1;
     docs.iter()
@@ -209,7 +206,7 @@ pub fn get_graphql_attr(attrs: &[Attribute]) -> Option<Vec<NestedMeta>> {
     for attr in attrs {
         match attr.parse_meta() {
             Ok(Meta::List(ref list)) if list.path.is_ident("graphql") => {
-                return Some(list.nested.iter().map(|x| x.clone()).collect());
+                return Some(list.nested.iter().cloned().collect());
             }
             _ => {}
         }
@@ -222,17 +219,17 @@ pub fn keyed_item_value(
     name: &str,
     validation: AttributeValidation,
 ) -> Option<AttributeValue> {
-    match item {
+    match *item {
         // Attributes in the form of `#[graphql(name = "value")]`.
-        &NestedMeta::Meta(Meta::NameValue(ref nameval)) if nameval.path.is_ident(name) => {
-            match &nameval.lit {
+        NestedMeta::Meta(Meta::NameValue(ref nameval)) if nameval.path.is_ident(name) => {
+            match nameval.lit {
                 // We have a string attribute value.
-                &Lit::Str(ref strlit) => Some(AttributeValue::String(strlit.value())),
+                Lit::Str(ref strlit) => Some(AttributeValue::String(strlit.value())),
                 _ => None,
             }
         }
         // Attributes in the form of `#[graphql(name)]`.
-        &NestedMeta::Meta(Meta::Path(ref path)) if path.is_ident(name) => match validation {
+        NestedMeta::Meta(Meta::Path(ref path)) if path.is_ident(name) => match validation {
             AttributeValidation::String => {
                 panic!(format!(
                     "Invalid format for attribute \"{:?}\": expected a string value",
diff --git a/juniper_codegen/src/util/parse_impl.rs b/juniper_codegen/src/util/parse_impl.rs
index 8ad40195..85e8e9d7 100644
--- a/juniper_codegen/src/util/parse_impl.rs
+++ b/juniper_codegen/src/util/parse_impl.rs
@@ -47,10 +47,7 @@ pub struct ImplBlock {
 impl ImplBlock {
     /// Check if the block has the special `resolve()` method.
     pub fn has_resolve_method(&self) -> bool {
-        self.methods
-            .iter()
-            .position(|m| m.sig.ident == "resolve")
-            .is_some()
+        self.methods.iter().any(|m| m.sig.ident == "resolve")
     }
 
     /// Parse a 'fn resolve()' method declaration found in union or interface
@@ -64,7 +61,7 @@ impl ImplBlock {
             return Err("Expect a method named 'fn resolve(...)".into());
         }
 
-        let _type = match &method.sig.output {
+        match &method.sig.output {
             syn::ReturnType::Type(_, _) => {
                 return Err("resolve() method must not have a declared return type".into());
             }
@@ -162,7 +159,7 @@ impl ImplBlock {
             }
         };
 
-        let target_trait = match _impl.trait_ {
+        let target_trait = match _impl.clone().trait_ {
             Some((_, path, _)) => {
                 let name = path
                     .segments
@@ -181,12 +178,12 @@ impl ImplBlock {
             panic!("Could not determine a name for the impl type");
         };
 
-        let target_type = _impl.self_ty;
+        let target_type = _impl.self_ty.clone();
 
         let description = attrs
             .description
             .clone()
-            .or(util::get_doc_comment(&_impl.attrs));
+            .or_else(|| util::get_doc_comment(&_impl.attrs.clone()));
 
         let mut methods = Vec::new();
 
diff --git a/juniper_iron/src/lib.rs b/juniper_iron/src/lib.rs
index f733dac6..1479a6ed 100644
--- a/juniper_iron/src/lib.rs
+++ b/juniper_iron/src/lib.rs
@@ -401,14 +401,6 @@ impl fmt::Display for GraphQLIronError {
 }
 
 impl Error for GraphQLIronError {
-    fn description(&self) -> &str {
-        match *self {
-            GraphQLIronError::Serde(ref err) => err.description(),
-            GraphQLIronError::Url(ref err) => err.description(),
-            GraphQLIronError::InvalidData(err) => err,
-        }
-    }
-
     fn cause(&self) -> Option<&dyn Error> {
         match *self {
             GraphQLIronError::Serde(ref err) => Some(err),
diff --git a/juniper_rocket/src/lib.rs b/juniper_rocket/src/lib.rs
index ca6c7ecf..fde19fc0 100644
--- a/juniper_rocket/src/lib.rs
+++ b/juniper_rocket/src/lib.rs
@@ -296,7 +296,7 @@ where
                 }
                 _ => {
                     if strict {
-                        return Err(format!("Prohibited extra field '{}'", key).to_owned());
+                        return Err(format!("Prohibited extra field '{}'", key));
                     }
                 }
             }