diff --git a/contrib/sync_db_pools/codegen/src/database.rs b/contrib/sync_db_pools/codegen/src/database.rs
index dc2324f5..989cc0a6 100644
--- a/contrib/sync_db_pools/codegen/src/database.rs
+++ b/contrib/sync_db_pools/codegen/src/database.rs
@@ -65,7 +65,7 @@ pub fn database_attr(attr: TokenStream, input: TokenStream) -> Result<TokenStrea
     let guard_type = &invocation.type_name;
     let vis = &invocation.visibility;
     let fairing_name = format!("'{}' Database Pool", name);
-    let span = conn_type.span().into();
+    let span = conn_type.span();
 
     // A few useful paths.
     let root = quote_spanned!(span => ::rocket_sync_db_pools);
diff --git a/contrib/sync_db_pools/lib/src/connection.rs b/contrib/sync_db_pools/lib/src/connection.rs
index 01d5a678..47e1b23e 100644
--- a/contrib/sync_db_pools/lib/src/connection.rs
+++ b/contrib/sync_db_pools/lib/src/connection.rs
@@ -138,7 +138,7 @@ impl<K: 'static, C: Poolable> ConnectionPool<K, C> {
 
     #[inline]
     pub async fn get_pool<P: Phase>(rocket: &Rocket<P>) -> Option<Self> {
-        rocket.state::<Self>().map(|pool| pool.clone())
+        rocket.state::<Self>().cloned()
     }
 }
 
diff --git a/core/codegen/src/attribute/catch/mod.rs b/core/codegen/src/attribute/catch/mod.rs
index 6f4bf61c..38eba36a 100644
--- a/core/codegen/src/attribute/catch/mod.rs
+++ b/core/codegen/src/attribute/catch/mod.rs
@@ -30,14 +30,14 @@ pub fn _catch(
 
     // This ensures that "Responder not implemented" points to the return type.
     let return_type_span = catch.function.sig.output.ty()
-        .map(|ty| ty.span().into())
-        .unwrap_or(Span::call_site().into());
+        .map(|ty| ty.span())
+        .unwrap_or_else(Span::call_site);
 
     // Set the `req` and `status` spans to that of their respective function
     // arguments for a more correct `wrong type` error span. `rev` to be cute.
     let codegen_args = &[__req, __status];
     let inputs = catch.function.sig.inputs.iter().rev()
-        .zip(codegen_args.into_iter())
+        .zip(codegen_args.iter())
         .map(|(fn_arg, codegen_arg)| match fn_arg {
             syn::FnArg::Receiver(_) => codegen_arg.respanned(fn_arg.span()),
             syn::FnArg::Typed(a) => codegen_arg.respanned(a.ty.span())
@@ -45,7 +45,7 @@ pub fn _catch(
 
     // We append `.await` to the function call if this is `async`.
     let dot_await = catch.function.sig.asyncness
-        .map(|a| quote_spanned!(a.span().into() => .await));
+        .map(|a| quote_spanned!(a.span() => .await));
 
     let catcher_response = quote_spanned!(return_type_span => {
         let ___responder = #user_catcher_fn_name(#(#inputs),*) #dot_await;
diff --git a/core/codegen/src/attribute/entry/launch.rs b/core/codegen/src/attribute/entry/launch.rs
index ca55d615..65834a9b 100644
--- a/core/codegen/src/attribute/entry/launch.rs
+++ b/core/codegen/src/attribute/entry/launch.rs
@@ -36,7 +36,7 @@ impl EntryAttr for Launch {
         };
 
         let block = &f.block;
-        let rocket = quote_spanned!(ty.span().into() => {
+        let rocket = quote_spanned!(ty.span() => {
             let ___rocket: #ty = #block;
             let ___rocket: ::rocket::Rocket<::rocket::Build> = ___rocket;
             ___rocket
@@ -47,7 +47,7 @@ impl EntryAttr for Launch {
         sig.output = syn::ReturnType::Default;
         sig.asyncness = None;
 
-        Ok(quote_spanned!(block.span().into() =>
+        Ok(quote_spanned!(block.span() =>
             #[allow(dead_code)] #f
 
             #vis #sig {
diff --git a/core/codegen/src/attribute/entry/main.rs b/core/codegen/src/attribute/entry/main.rs
index 52287b56..66e7a1cb 100644
--- a/core/codegen/src/attribute/entry/main.rs
+++ b/core/codegen/src/attribute/entry/main.rs
@@ -21,7 +21,7 @@ impl EntryAttr for Main {
         }
 
         sig.asyncness = None;
-        Ok(quote_spanned!(block.span().into() => #(#attrs)* #vis #sig {
+        Ok(quote_spanned!(block.span() => #(#attrs)* #vis #sig {
             ::rocket::async_main(async move #block)
         }))
     }
diff --git a/core/codegen/src/attribute/entry/mod.rs b/core/codegen/src/attribute/entry/mod.rs
index 38947777..9ed98bc0 100644
--- a/core/codegen/src/attribute/entry/mod.rs
+++ b/core/codegen/src/attribute/entry/mod.rs
@@ -35,7 +35,7 @@ fn _async_entry<A: EntryAttr>(
             .span_note(function.sig.span(), "this function must take no arguments"));
     }
 
-    A::function(&mut function).map(|t| t.into())
+    A::function(&mut function)
 }
 
 macro_rules! async_entry {
diff --git a/core/codegen/src/attribute/entry/test.rs b/core/codegen/src/attribute/entry/test.rs
index 8c197719..bd83a9cb 100644
--- a/core/codegen/src/attribute/entry/test.rs
+++ b/core/codegen/src/attribute/entry/test.rs
@@ -12,7 +12,7 @@ impl EntryAttr for Test {
     fn function(f: &mut syn::ItemFn) -> Result<TokenStream> {
         let (attrs, vis, block, sig) = (&f.attrs, &f.vis, &f.block, &mut f.sig);
         sig.asyncness = None;
-        Ok(quote_spanned!(block.span().into() => #(#attrs)* #[test] #vis #sig {
+        Ok(quote_spanned!(block.span() => #(#attrs)* #[test] #vis #sig {
             ::rocket::async_test(async move #block)
         }))
     }
diff --git a/core/codegen/src/attribute/route/mod.rs b/core/codegen/src/attribute/route/mod.rs
index 71218a38..b162ff5a 100644
--- a/core/codegen/src/attribute/route/mod.rs
+++ b/core/codegen/src/attribute/route/mod.rs
@@ -228,7 +228,7 @@ fn internal_uri_macro_decl(route: &Route) -> TokenStream {
 fn responder_outcome_expr(route: &Route) -> TokenStream {
     let ret_span = match route.handler.sig.output {
         syn::ReturnType::Default => route.handler.sig.ident.span(),
-        syn::ReturnType::Type(_, ref ty) => ty.span().into()
+        syn::ReturnType::Type(_, ref ty) => ty.span()
     };
 
     let user_handler_fn_name = &route.handler.sig.ident;
@@ -236,7 +236,7 @@ fn responder_outcome_expr(route: &Route) -> TokenStream {
         .map(|(ident, _)| ident.rocketized());
 
     let _await = route.handler.sig.asyncness
-        .map(|a| quote_spanned!(a.span().into() => .await));
+        .map(|a| quote_spanned!(a.span() => .await));
 
     define_spanned_export!(ret_span => __req, _route);
     quote_spanned! { ret_span =>
@@ -375,12 +375,12 @@ fn codegen_route(route: Route) -> Result<TokenStream> {
 
         /// Rocket code generated wrapping URI macro.
         #internal_uri_macro
-    }.into())
+    })
 }
 
 fn complete_route(args: TokenStream, input: TokenStream) -> Result<TokenStream> {
     let function: syn::ItemFn = syn::parse2(input)
-        .map_err(|e| Diagnostic::from(e))
+        .map_err(Diagnostic::from)
         .map_err(|diag| diag.help("`#[route]` can only be used on functions"))?;
 
     let attr_tokens = quote!(route(#args));
@@ -398,10 +398,10 @@ fn incomplete_route(
     let method_span = StringLit::new(format!("#[{}]", method), Span::call_site())
         .subspan(2..2 + method_str.len());
 
-    let method_ident = syn::Ident::new(&method_str, method_span.into());
+    let method_ident = syn::Ident::new(&method_str, method_span);
 
     let function: syn::ItemFn = syn::parse2(input)
-        .map_err(|e| Diagnostic::from(e))
+        .map_err(Diagnostic::from)
         .map_err(|d| d.help(format!("#[{}] can only be used on functions", method_str)))?;
 
     let full_attr = quote!(#method_ident(#args));
diff --git a/core/codegen/src/attribute/route/parse.rs b/core/codegen/src/attribute/route/parse.rs
index 98d2191f..02ceaac6 100644
--- a/core/codegen/src/attribute/route/parse.rs
+++ b/core/codegen/src/attribute/route/parse.rs
@@ -84,7 +84,7 @@ impl FromMeta for RouteUri {
                     .and_then(|q| q.find("&&"))
                     .map(|i| origin.path().len() + 1 + i))
                 .map(|i| string.subspan((1 + i)..(1 + i + 2)))
-                .unwrap_or(string.span());
+                .unwrap_or_else(|| string.span());
 
             return Err(span.error("route URIs cannot contain empty segments")
                 .note(format!("expected \"{}\", found \"{}\"", normalized, origin)));
@@ -103,7 +103,7 @@ impl FromMeta for RouteUri {
 
 impl Route {
     pub fn upgrade_param(param: Parameter, args: &Arguments) -> Result<Parameter> {
-        if !param.dynamic().is_some() {
+        if param.dynamic().is_none() {
             return Ok(param);
         }
 
@@ -160,14 +160,14 @@ impl Route {
         let (source, span) = (attr.uri.path(), attr.uri.path_span);
         let path_params = Parameter::parse_many::<fmt::Path>(source.as_str(), span)
             .map(|p| Route::upgrade_param(p?, &arguments))
-            .filter_map(|p| p.map_err(|e| diags.push(e.into())).ok())
+            .filter_map(|p| p.map_err(|e| diags.push(e)).ok())
             .collect::<Vec<_>>();
 
         // Parse and collect the query parameters.
         let query_params = match (attr.uri.query(), attr.uri.query_span) {
             (Some(q), Some(span)) => Parameter::parse_many::<fmt::Query>(q.as_str(), span)
                 .map(|p| Route::upgrade_param(p?, &arguments))
-                .filter_map(|p| p.map_err(|e| diags.push(e.into())).ok())
+                .filter_map(|p| p.map_err(|e| diags.push(e)).ok())
                 .collect::<Vec<_>>(),
             _ => vec![]
         };
@@ -175,7 +175,7 @@ impl Route {
         // Remove the `SpanWrapped` layer and upgrade to a guard.
         let data_guard = attr.data.clone()
             .map(|p| Route::upgrade_dynamic(p.value, &arguments))
-            .and_then(|p| p.map_err(|e| diags.push(e.into())).ok());
+            .and_then(|p| p.map_err(|e| diags.push(e)).ok());
 
         // Collect all of the declared dynamic route parameters.
         let all_dyn_params = path_params.iter().filter_map(|p| p.dynamic())
diff --git a/core/codegen/src/bang/test_guide.rs b/core/codegen/src/bang/test_guide.rs
index 8de5b160..6c61e748 100644
--- a/core/codegen/src/bang/test_guide.rs
+++ b/core/codegen/src/bang/test_guide.rs
@@ -6,7 +6,7 @@ use devise::ext::SpanDiagnosticExt;
 use proc_macro2::TokenStream;
 
 pub fn _macro(input: proc_macro::TokenStream) -> devise::Result<TokenStream> {
-    let root_glob = syn::parse::<LitStr>(input.into())?;
+    let root_glob = syn::parse::<LitStr>(input)?;
     let tests = entry_to_tests(&root_glob)
         .map_err(|e| root_glob.span().error(format!("failed to read: {}", e)))?;
 
@@ -24,7 +24,7 @@ fn entry_to_tests(root_glob: &LitStr) -> Result<Vec<TokenStream>, Box<dyn Error>
             .and_then(|f| f.to_str())
             .map(|name| name.trim_matches(|c| char::is_numeric(c) || c == '-')
                 .replace(|c| c == '-' || c == '.', "_"))
-            .ok_or_else(|| "invalid file name")?;
+            .ok_or("invalid file name")?;
 
         let ident = Ident::new(&name.to_lowercase(), root_glob.span());
         let full_path = Path::new(&manifest_dir).join(&path).display().to_string();
diff --git a/core/codegen/src/bang/uri.rs b/core/codegen/src/bang/uri.rs
index c8715fc1..5ff50d50 100644
--- a/core/codegen/src/bang/uri.rs
+++ b/core/codegen/src/bang/uri.rs
@@ -28,7 +28,7 @@ pub fn prefix_last_segment(path: &mut syn::Path, prefix: &str) {
 }
 
 pub fn _uri_macro(input: TokenStream) -> Result<TokenStream> {
-    let input2: TokenStream = input.clone().into();
+    let input2: TokenStream = input.clone();
     match syn::parse2::<UriMacro>(input)? {
         UriMacro::Routed(ref mut mac) => {
             prefix_last_segment(&mut mac.route.path, URI_MACRO_PREFIX);
@@ -39,10 +39,10 @@ pub fn _uri_macro(input: TokenStream) -> Result<TokenStream> {
     }
 }
 
-fn extract_exprs<'a>(internal: &'a InternalUriParams) -> Result<(
-        impl Iterator<Item = &'a Expr>,                // path exprs
-        impl Iterator<Item = &'a ArgExpr>,             // query exprs
-        impl Iterator<Item = (&'a Ident, &'a Type)>,   // types for both path || query
+fn extract_exprs(internal: &InternalUriParams) -> Result<(
+        impl Iterator<Item = &Expr>,             // path exprs
+        impl Iterator<Item = &ArgExpr>,          // query exprs
+        impl Iterator<Item = (&Ident, &Type)>,   // types for both path || query
     )>
 {
     let route_name = &internal.uri_mac.route.path;
@@ -51,7 +51,7 @@ fn extract_exprs<'a>(internal: &'a InternalUriParams) -> Result<(
             let path_params = internal.dynamic_path_params();
             let path_param_count = path_params.clone().count();
             for expr in exprs.iter().take(path_param_count) {
-                if !expr.as_expr().is_some() {
+                if expr.as_expr().is_none() {
                     return Err(expr.span().error("path parameters cannot be ignored"));
                 }
             }
diff --git a/core/codegen/src/bang/uri_parsing.rs b/core/codegen/src/bang/uri_parsing.rs
index 3dd3d11e..ad7db5f2 100644
--- a/core/codegen/src/bang/uri_parsing.rs
+++ b/core/codegen/src/bang/uri_parsing.rs
@@ -127,7 +127,7 @@ pub struct FnArg {
 }
 
 fn err<T, S: AsRef<str>>(span: Span, s: S) -> parse::Result<T> {
-    Err(parse::Error::new(span.into(), s.as_ref()))
+    Err(parse::Error::new(span, s.as_ref()))
 }
 
 impl Parse for ArgExpr {
@@ -261,7 +261,7 @@ impl Parse for UriMacro {
 
             stream.is_empty()
                 .then(|| Ok((None, cursor)))
-                .unwrap_or_else(|| Ok((Some(stream), cursor)))
+                .unwrap_or(Ok((Some(stream), cursor)))
         }
 
         let mut args = vec![];
@@ -276,7 +276,7 @@ impl Parse for UriMacro {
             1 => UriMacro::unary.parse2(next()),
             2 => UriMacro::binary(next(), next()),
             3 => UriMacro::ternary(next(), next(), next()),
-            n => err(iter.skip(3).next().unwrap().span(),
+            n => err(iter.nth(3).unwrap().span(),
                 format!("expected 1, 2, or 3 arguments, found {}", n))
         }
     }
@@ -479,7 +479,7 @@ fn uri_err<T>(lit: &StringLit, error: Error<'_>) -> parse::Result<T> {
 
 impl UriExpr {
     fn parse_prefix(input: ParseStream<'_>) -> syn::Result<Option<Self>> {
-        if let Ok(_) = input.parse::<Token![_]>() {
+        if input.parse::<Token![_]>().is_ok() {
             return Ok(None);
         }
 
@@ -490,7 +490,7 @@ impl UriExpr {
         let lit = input.parse::<StringLit>()?;
         let uri = Uri::parse::<Origin<'_>>(&lit)
             .or_else(|e| Uri::parse::<Absolute<'_>>(&lit).map_err(|e2| (e, e2)))
-            .map_err(|(e1, e2)| lit.starts_with('/').then(|| e1).unwrap_or_else(|| e2))
+            .map_err(|(e1, e2)| lit.starts_with('/').then(|| e1).unwrap_or(e2))
             .or_else(|e| uri_err(&lit, e))?;
 
         if matches!(&uri, Uri::Origin(o) if o.query().is_some())
@@ -503,7 +503,7 @@ impl UriExpr {
     }
 
     fn parse_suffix(input: ParseStream<'_>) -> syn::Result<Option<Self>> {
-        if let Ok(_) = input.parse::<Token![_]>() {
+        if input.parse::<Token![_]>().is_ok() {
             return Ok(None);
         }
 
diff --git a/core/codegen/src/derive/form_field.rs b/core/codegen/src/derive/form_field.rs
index 92d9fbbb..4ce26036 100644
--- a/core/codegen/src/derive/form_field.rs
+++ b/core/codegen/src/derive/form_field.rs
@@ -301,7 +301,7 @@ impl VisitMut for ValidationMutator<'_> {
             }
         }
 
-        return syn::visit_mut::visit_expr_mut(self, i);
+        syn::visit_mut::visit_expr_mut(self, i);
     }
 }
 
@@ -385,10 +385,10 @@ pub fn default<'v>(field: Field<'v>) -> Result<Option<TokenStream>> {
     let ty = field.stripped_ty();
     match (default, default_with) {
         (Some(e1), Some(e2)) => {
-            return Err(e1.span()
+            Err(e1.span()
                 .error("duplicate default expressions")
                 .help("only one of `default` or `default_with` must be used")
-                .span_note(e2.span(), "other default expression is here"));
+                .span_note(e2.span(), "other default expression is here"))
         },
         (Some(e), None) | (None, Some(e)) => {
             Ok(Some(quote_spanned!(e.span() => {
@@ -420,8 +420,8 @@ pub fn first_duplicate<K: Spanned, V: PartialEq + Spanned>(
     let key = |k| key_map.iter().find(|(i, _)| k < *i).expect("k < *i");
 
     for (i, a) in all_values.iter().enumerate() {
-        let rest = all_values.iter().enumerate().skip(i + 1);
-        if let Some((j, b)) = rest.filter(|(_, b)| *b == a).next() {
+        let mut rest = all_values.iter().enumerate().skip(i + 1);
+        if let Some((j, b)) = rest.find(|(_, b)| *b == a) {
             let (a_i, key_a) = key(i);
             let (b_i, key_b) = key(j);
 
diff --git a/core/codegen/src/derive/responder.rs b/core/codegen/src/derive/responder.rs
index 589d10aa..64df49e8 100644
--- a/core/codegen/src/derive/responder.rs
+++ b/core/codegen/src/derive/responder.rs
@@ -59,7 +59,7 @@ pub fn derive_responder(input: proc_macro::TokenStream) -> TokenStream {
                 false => Ok(())
             })
             .fields_validate(|_, fields| match fields.is_empty() {
-                true => return Err(fields.span().error("need at least one field")),
+                true => Err(fields.span().error("need at least one field")),
                 false => Ok(())
             })
         )
@@ -71,7 +71,7 @@ pub fn derive_responder(input: proc_macro::TokenStream) -> TokenStream {
             })
             .try_fields_map(|_, fields| {
                 fn set_header_tokens<T: ToTokens + Spanned>(item: T) -> TokenStream {
-                    quote_spanned!(item.span().into() => __res.set_header(#item);)
+                    quote_spanned!(item.span() => __res.set_header(#item);)
                 }
 
                 let attr = ItemAttr::one_from_attrs("response", fields.parent.attrs())?
@@ -98,7 +98,7 @@ pub fn derive_responder(input: proc_macro::TokenStream) -> TokenStream {
 
                 let content_type = attr.content_type.map(set_header_tokens);
                 let status = attr.status.map(|status| {
-                    quote_spanned!(status.span().into() => __res.set_status(#status);)
+                    quote_spanned!(status.span() => __res.set_status(#status);)
                 });
 
                 Ok(quote! {
diff --git a/core/codegen/src/derive/uri_display.rs b/core/codegen/src/derive/uri_display.rs
index eaa00792..c625286a 100644
--- a/core/codegen/src/derive/uri_display.rs
+++ b/core/codegen/src/derive/uri_display.rs
@@ -38,7 +38,7 @@ pub fn derive_uri_display_query(input: proc_macro::TokenStream) -> TokenStream {
         .validator(ValidatorBuild::new()
             .enum_validate(|_, data| {
                 if data.variants().count() == 0 {
-                    return Err(data.brace_token.span.error(NO_EMPTY_ENUMS));
+                    Err(data.brace_token.span.error(NO_EMPTY_ENUMS))
                 } else {
                     Ok(())
                 }
@@ -80,7 +80,7 @@ pub fn derive_uri_display_query(input: proc_macro::TokenStream) -> TokenStream {
                 })
             })
             .try_field_map(|_, field| {
-                let span = field.span().into();
+                let span = field.span();
                 let accessor = field.accessor();
                 let tokens = if let Some(name) = field.first_field_name()? {
                     quote_spanned!(span => f.write_named_value(#name, &#accessor)?;)
@@ -100,13 +100,13 @@ pub fn derive_uri_display_query(input: proc_macro::TokenStream) -> TokenStream {
 
     let from_self = from_uri_param::<fmt::Query>(input.clone(), quote!(Self));
     let from_ref = from_uri_param::<fmt::Query>(input.clone(), quote!(&'__r Self));
-    let from_mut = from_uri_param::<fmt::Query>(input.clone(), quote!(&'__r mut Self));
+    let from_mut = from_uri_param::<fmt::Query>(input, quote!(&'__r mut Self));
 
-    let mut ts = TokenStream::from(uri_display);
-    ts.extend(TokenStream::from(from_self));
-    ts.extend(TokenStream::from(from_ref));
-    ts.extend(TokenStream::from(from_mut));
-    ts.into()
+    let mut ts = uri_display;
+    ts.extend(from_self);
+    ts.extend(from_ref);
+    ts.extend(from_mut);
+    ts
 }
 
 #[allow(non_snake_case)]
@@ -141,13 +141,13 @@ pub fn derive_uri_display_path(input: proc_macro::TokenStream) -> TokenStream {
 
     let from_self = from_uri_param::<fmt::Path>(input.clone(), quote!(Self));
     let from_ref = from_uri_param::<fmt::Path>(input.clone(), quote!(&'__r Self));
-    let from_mut = from_uri_param::<fmt::Path>(input.clone(), quote!(&'__r mut Self));
+    let from_mut = from_uri_param::<fmt::Path>(input, quote!(&'__r mut Self));
 
-    let mut ts = TokenStream::from(uri_display);
-    ts.extend(TokenStream::from(from_self));
-    ts.extend(TokenStream::from(from_ref));
-    ts.extend(TokenStream::from(from_mut));
-    ts.into()
+    let mut ts = uri_display;
+    ts.extend(from_self);
+    ts.extend(from_ref);
+    ts.extend(from_mut);
+    ts
 }
 
 fn from_uri_param<P: fmt::Part>(input: proc_macro::TokenStream, ty: TokenStream) -> TokenStream {
diff --git a/core/codegen/src/http_codegen.rs b/core/codegen/src/http_codegen.rs
index 28418f59..8d021a38 100644
--- a/core/codegen/src/http_codegen.rs
+++ b/core/codegen/src/http_codegen.rs
@@ -56,7 +56,7 @@ impl FromMeta for ContentType {
     fn from_meta(meta: &MetaItem) -> Result<Self> {
         http::ContentType::parse_flexible(&String::from_meta(meta)?)
             .map(ContentType)
-            .ok_or(meta.value_span().error("invalid or unknown content type"))
+            .ok_or_else(|| meta.value_span().error("invalid or unknown content type"))
     }
 }
 
@@ -71,7 +71,7 @@ impl ToTokens for ContentType {
 impl FromMeta for MediaType {
     fn from_meta(meta: &MetaItem) -> Result<Self> {
         let mt = http::MediaType::parse_flexible(&String::from_meta(meta)?)
-            .ok_or(meta.value_span().error("invalid or unknown media type"))?;
+            .ok_or_else(|| meta.value_span().error("invalid or unknown media type"))?;
 
         if !mt.is_known() {
             // FIXME(diag: warning)
diff --git a/core/codegen/src/syn_ext.rs b/core/codegen/src/syn_ext.rs
index 276a4ae4..608a914c 100644
--- a/core/codegen/src/syn_ext.rs
+++ b/core/codegen/src/syn_ext.rs
@@ -212,15 +212,12 @@ impl TypeExt for syn::Type {
                 match ty {
                     Path(t) if self.1.iter().any(|i| t.path.is_ident(*i)) => {
                         self.0 = false;
-                        return;
                     }
                     ImplTrait(_) | Infer(_) | Macro(_) => {
                         self.0 = false;
-                        return;
                     }
                     BareFn(_) | Never(_) => {
                         self.0 = true;
-                        return;
                     },
                     _ => syn::visit::visit_type(self, ty),
                 }
diff --git a/core/codegen/tests/ui-fail-nightly/responder-types.stderr b/core/codegen/tests/ui-fail-nightly/responder-types.stderr
index 5853d181..b091b3d7 100644
--- a/core/codegen/tests/ui-fail-nightly/responder-types.stderr
+++ b/core/codegen/tests/ui-fail-nightly/responder-types.stderr
@@ -14,7 +14,10 @@ error[E0277]: the trait bound `Header<'_>: From<u8>` is not satisfied
    |
    = help: the following implementations were found:
              <Header<'static> as From<&Cookie<'_>>>
-             <Header<'static> as From<Cookie<'_>>>
+             <Header<'static> as From<&ExpectCt>>
+             <Header<'static> as From<&Frame>>
+             <Header<'static> as From<&Hsts>>
+           and 8 others
    = note: required because of the requirements on the impl of `Into<Header<'_>>` for `u8`
 
 error[E0277]: the trait bound `u8: Responder<'_, '_>` is not satisfied
@@ -33,7 +36,10 @@ error[E0277]: the trait bound `Header<'_>: From<u8>` is not satisfied
    |
    = help: the following implementations were found:
              <Header<'static> as From<&Cookie<'_>>>
-             <Header<'static> as From<Cookie<'_>>>
+             <Header<'static> as From<&ExpectCt>>
+             <Header<'static> as From<&Frame>>
+             <Header<'static> as From<&Hsts>>
+           and 8 others
    = note: required because of the requirements on the impl of `Into<Header<'_>>` for `u8`
 
 error[E0277]: the trait bound `Header<'_>: From<std::string::String>` is not satisfied
@@ -44,7 +50,10 @@ error[E0277]: the trait bound `Header<'_>: From<std::string::String>` is not sat
    |
    = help: the following implementations were found:
              <Header<'static> as From<&Cookie<'_>>>
-             <Header<'static> as From<Cookie<'_>>>
+             <Header<'static> as From<&ExpectCt>>
+             <Header<'static> as From<&Frame>>
+             <Header<'static> as From<&Hsts>>
+           and 8 others
    = note: required because of the requirements on the impl of `Into<Header<'_>>` for `std::string::String`
 
 error[E0277]: the trait bound `usize: Responder<'_, '_>` is not satisfied
diff --git a/core/codegen/tests/ui-fail-stable/responder-types.stderr b/core/codegen/tests/ui-fail-stable/responder-types.stderr
index 66b9d3a6..61801f4f 100644
--- a/core/codegen/tests/ui-fail-stable/responder-types.stderr
+++ b/core/codegen/tests/ui-fail-stable/responder-types.stderr
@@ -14,7 +14,10 @@ error[E0277]: the trait bound `Header<'_>: From<u8>` is not satisfied
    |
    = help: the following implementations were found:
              <Header<'static> as From<&Cookie<'_>>>
-             <Header<'static> as From<Cookie<'_>>>
+             <Header<'static> as From<&ExpectCt>>
+             <Header<'static> as From<&Frame>>
+             <Header<'static> as From<&Hsts>>
+           and 8 others
    = note: required because of the requirements on the impl of `Into<Header<'_>>` for `u8`
 
 error[E0277]: the trait bound `u8: Responder<'_, '_>` is not satisfied
@@ -33,7 +36,10 @@ error[E0277]: the trait bound `Header<'_>: From<u8>` is not satisfied
    |
    = help: the following implementations were found:
              <Header<'static> as From<&Cookie<'_>>>
-             <Header<'static> as From<Cookie<'_>>>
+             <Header<'static> as From<&ExpectCt>>
+             <Header<'static> as From<&Frame>>
+             <Header<'static> as From<&Hsts>>
+           and 8 others
    = note: required because of the requirements on the impl of `Into<Header<'_>>` for `u8`
 
 error[E0277]: the trait bound `Header<'_>: From<std::string::String>` is not satisfied
@@ -44,7 +50,10 @@ error[E0277]: the trait bound `Header<'_>: From<std::string::String>` is not sat
    |
    = help: the following implementations were found:
              <Header<'static> as From<&Cookie<'_>>>
-             <Header<'static> as From<Cookie<'_>>>
+             <Header<'static> as From<&ExpectCt>>
+             <Header<'static> as From<&Frame>>
+             <Header<'static> as From<&Hsts>>
+           and 8 others
    = note: required because of the requirements on the impl of `Into<Header<'_>>` for `std::string::String`
 
 error[E0277]: the trait bound `usize: Responder<'_, '_>` is not satisfied
diff --git a/core/http/src/header/accept.rs b/core/http/src/header/accept.rs
index e133f113..305272a6 100644
--- a/core/http/src/header/accept.rs
+++ b/core/http/src/header/accept.rs
@@ -210,7 +210,7 @@ impl Accept {
     /// assert_eq!(iter.next(), None);
     /// ```
     #[inline(always)]
-    pub fn iter<'a>(&'a self) -> impl Iterator<Item=&'a QMediaType> + 'a {
+    pub fn iter(&self) -> impl Iterator<Item=&'_ QMediaType> + '_ {
         match self.0 {
             AcceptParams::Static(ref val) => Either::Left(Some(val).into_iter()),
             AcceptParams::Dynamic(ref vec) => Either::Right(vec.iter())
@@ -239,7 +239,7 @@ impl Accept {
     /// assert_eq!(iter.next(), None);
     /// ```
     #[inline(always)]
-    pub fn media_types<'a>(&'a self) -> impl Iterator<Item=&'a MediaType> + 'a {
+    pub fn media_types(&self) -> impl Iterator<Item=&'_ MediaType> + '_ {
         self.iter().map(|weighted_mt| weighted_mt.media_type())
     }
 
@@ -285,10 +285,10 @@ impl FromStr for Accept {
 
 /// Creates a new `Header` with name `Accept` and the value set to the HTTP
 /// rendering of this `Accept` header.
-impl Into<Header<'static>> for Accept {
+impl From<Accept> for Header<'static> {
     #[inline(always)]
-    fn into(self) -> Header<'static> {
-        Header::new("Accept", self.to_string())
+    fn from(val: Accept) -> Self {
+        Header::new("Accept", val.to_string())
     }
 }
 
@@ -380,47 +380,47 @@ impl Extend<QMediaType> for AcceptParams {
 mod test {
     use crate::{Accept, MediaType};
 
-    macro_rules! assert_preference {
-        ($string:expr, $expect:expr) => (
-            let accept: Accept = $string.parse().expect("accept string parse");
-            let expected: MediaType = $expect.parse().expect("media type parse");
-            let preferred = accept.preferred();
-            assert_eq!(preferred.media_type().to_string(), expected.to_string());
-        )
+    #[track_caller]
+    fn assert_preference(string: &str, expect: &str) {
+        let accept: Accept = string.parse().expect("accept string parse");
+        let expected: MediaType = expect.parse().expect("media type parse");
+        let preferred = accept.preferred();
+        let actual = preferred.media_type();
+        if *actual != expected {
+            panic!("mismatch for {}: expected {}, got {}", string, expected, actual)
+        }
     }
 
     #[test]
     fn test_preferred() {
-        assert_preference!("text/*", "text/*");
-        assert_preference!("text/*, text/html", "text/html");
-        assert_preference!("text/*; q=0.1, text/html", "text/html");
-        assert_preference!("text/*; q=1, text/html", "text/html");
-        assert_preference!("text/html, text/*", "text/html");
-        assert_preference!("text/*, text/html", "text/html");
-        assert_preference!("text/html, text/*; q=1", "text/html");
-        assert_preference!("text/html; q=1, text/html", "text/html");
-        assert_preference!("text/html, text/*; q=0.1", "text/html");
+        assert_preference("text/*", "text/*");
+        assert_preference("text/*, text/html", "text/html");
+        assert_preference("text/*; q=0.1, text/html", "text/html");
+        assert_preference("text/*; q=1, text/html", "text/html");
+        assert_preference("text/html, text/*", "text/html");
+        assert_preference("text/*, text/html", "text/html");
+        assert_preference("text/html, text/*; q=1", "text/html");
+        assert_preference("text/html; q=1, text/html", "text/html");
+        assert_preference("text/html, text/*; q=0.1", "text/html");
 
-        assert_preference!("text/html, application/json", "text/html");
-        assert_preference!("text/html, application/json; q=1", "text/html");
-        assert_preference!("application/json; q=1, text/html", "text/html");
+        assert_preference("text/html, application/json", "text/html");
+        assert_preference("text/html, application/json; q=1", "text/html");
+        assert_preference("application/json; q=1, text/html", "text/html");
 
-        assert_preference!("text/*, application/json", "application/json");
-        assert_preference!("*/*, text/*", "text/*");
-        assert_preference!("*/*, text/*, text/plain", "text/plain");
+        assert_preference("text/*, application/json", "application/json");
+        assert_preference("*/*, text/*", "text/*");
+        assert_preference("*/*, text/*, text/plain", "text/plain");
 
-        assert_preference!("a/b; q=0.1, a/b; q=0.2", "a/b; q=0.2");
-        assert_preference!("a/b; q=0.1, b/c; q=0.2", "b/c; q=0.2");
-        assert_preference!("a/b; q=0.5, b/c; q=0.2", "a/b; q=0.5");
+        assert_preference("a/b; q=0.1, a/b; q=0.2", "a/b; q=0.2");
+        assert_preference("a/b; q=0.1, b/c; q=0.2", "b/c; q=0.2");
+        assert_preference("a/b; q=0.5, b/c; q=0.2", "a/b; q=0.5");
 
-        assert_preference!("a/b; q=0.5, b/c; q=0.2, c/d", "c/d");
-        assert_preference!("a/b; q=0.5; v=1, a/b", "a/b");
+        assert_preference("a/b; q=0.5, b/c; q=0.2, c/d", "c/d");
+        assert_preference("a/b; q=0.5; v=1, a/b", "a/b");
 
-        assert_preference!("a/b; v=1, a/b; v=1; c=2", "a/b; v=1; c=2");
-        assert_preference!("a/b; v=1; c=2, a/b; v=1", "a/b; v=1; c=2");
-        assert_preference!("a/b; q=0.5; v=1, a/b; q=0.5; v=1; c=2",
-            "a/b; q=0.5; v=1; c=2");
-        assert_preference!("a/b; q=0.6; v=1, a/b; q=0.5; v=1; c=2",
-            "a/b; q=0.6; v=1");
+        assert_preference("a/b; v=1, a/b; v=1; c=2", "a/b; v=1; c=2");
+        assert_preference("a/b; v=1; c=2, a/b; v=1", "a/b; v=1; c=2");
+        assert_preference("a/b; q=0.5; v=1, a/b; q=0.5; v=1; c=2", "a/b; q=0.5; v=1; c=2");
+        assert_preference("a/b; q=0.6; v=1, a/b; q=0.5; v=1; c=2", "a/b; q=0.6; v=1");
     }
 }
diff --git a/core/http/src/header/content_type.rs b/core/http/src/header/content_type.rs
index 77654ba1..74f728ec 100644
--- a/core/http/src/header/content_type.rs
+++ b/core/http/src/header/content_type.rs
@@ -382,13 +382,13 @@ impl fmt::Display for ContentType {
 
 /// Creates a new `Header` with name `Content-Type` and the value set to the
 /// HTTP rendering of this Content-Type.
-impl Into<Header<'static>> for ContentType {
+impl From<ContentType> for Header<'static> {
     #[inline(always)]
-    fn into(self) -> Header<'static> {
-        if let Some(src) = self.known_source() {
+    fn from(content_type: ContentType) -> Self {
+        if let Some(src) = content_type.known_source() {
             Header::new("Content-Type", src)
         } else {
-            Header::new("Content-Type", self.to_string())
+            Header::new("Content-Type", content_type.to_string())
         }
     }
 }
diff --git a/core/http/src/header/media_type.rs b/core/http/src/header/media_type.rs
index 69fc514b..7e8f219a 100644
--- a/core/http/src/header/media_type.rs
+++ b/core/http/src/header/media_type.rs
@@ -546,9 +546,9 @@ impl MediaType {
     /// assert_eq!(png.params().count(), 0);
     /// ```
     #[inline]
-    pub fn params<'a>(&'a self) -> impl Iterator<Item=(&'a UncasedStr, &'a str)> + 'a {
+    pub fn params(&self) -> impl Iterator<Item=(&'_ UncasedStr, &'_ str)> + '_ {
         let raw = match self.params {
-            MediaParams::Static(ref slice) => Either::Left(slice.iter().cloned()),
+            MediaParams::Static(slice) => Either::Left(slice.iter().cloned()),
             MediaParams::Dynamic(ref vec) => {
                 Either::Right(vec.iter().map(move |&(ref key, ref val)| {
                     let source_str = self.source.as_str();
diff --git a/core/http/src/parse/indexed.rs b/core/http/src/parse/indexed.rs
index 3d1a13e0..185a1168 100644
--- a/core/http/src/parse/indexed.rs
+++ b/core/http/src/parse/indexed.rs
@@ -49,7 +49,7 @@ impl<A, T: ?Sized + ToOwned> From<Extent<A>> for Indexed<'_, T> {
 impl<'a, T: ?Sized + ToOwned + 'a> From<Cow<'a, T>> for Indexed<'a, T> {
     #[inline(always)]
     fn from(value: Cow<'a, T>) -> Indexed<'a, T> {
-        Indexed::Concrete(value.into())
+        Indexed::Concrete(value)
     }
 }
 
diff --git a/core/http/src/parse/uri/error.rs b/core/http/src/parse/uri/error.rs
index d5565689..1deda621 100644
--- a/core/http/src/parse/uri/error.rs
+++ b/core/http/src/parse/uri/error.rs
@@ -1,4 +1,4 @@
-use std::fmt;
+use std::{fmt, convert};
 use std::borrow::Cow;
 
 use pear::error::Expected;
@@ -21,7 +21,7 @@ pub struct Error<'a> {
 #[doc(hidden)]
 impl<'a> From<ParseError<RawInput<'a>>> for Error<'a> {
     fn from(inner: ParseError<RawInput<'a>>) -> Self {
-        let expected = inner.error.map(|t| t.into(), |v| v.values.into());
+        let expected = inner.error.map(convert::identity, |v| v.values.into());
         Error { expected, index: inner.info.context.start }
     }
 }
diff --git a/core/http/src/parse/uri/parser.rs b/core/http/src/parse/uri/parser.rs
index 48e6d35f..b9ea37fd 100644
--- a/core/http/src/parse/uri/parser.rs
+++ b/core/http/src/parse/uri/parser.rs
@@ -52,7 +52,7 @@ pub fn asterisk<'a>(input: &mut RawInput<'a>) -> Result<'a, Asterisk> {
 #[parser]
 pub fn origin<'a>(input: &mut RawInput<'a>) -> Result<'a, Origin<'a>> {
     let (_, path, query) = (peek(b'/')?, path()?, query()?);
-    unsafe { Origin::raw(input.start.into(), path.into(), query) }
+    unsafe { Origin::raw(input.start.into(), path, query) }
 }
 
 #[parser]
diff --git a/core/http/src/raw_str.rs b/core/http/src/raw_str.rs
index c9377409..682efce8 100644
--- a/core/http/src/raw_str.rs
+++ b/core/http/src/raw_str.rs
@@ -114,7 +114,7 @@ impl RawStr {
     /// let cow_raw = RawStr::from_cow_str(cow_str);
     /// assert_eq!(cow_raw.as_str(), "hello!");
     /// ```
-    pub fn from_cow_str<'a>(cow: Cow<'a, str>) -> Cow<'a, RawStr> {
+    pub fn from_cow_str(cow: Cow<'_, str>) -> Cow<'_, RawStr> {
         match cow {
             Cow::Borrowed(b) => Cow::Borrowed(b.into()),
             Cow::Owned(b) => Cow::Owned(b.into()),
@@ -136,7 +136,7 @@ impl RawStr {
     /// let cow_str = RawStr::into_cow_str(cow_raw);
     /// assert_eq!(&*cow_str, "hello!");
     /// ```
-    pub fn into_cow_str<'a>(cow: Cow<'a, RawStr>) -> Cow<'a, str> {
+    pub fn into_cow_str(cow: Cow<'_, RawStr>) -> Cow<'_, str> {
         match cow {
             Cow::Borrowed(b) => Cow::Borrowed(b.as_str()),
             Cow::Owned(b) => Cow::Owned(b.into_string()),
diff --git a/core/http/src/uri/fmt/from_uri_param.rs b/core/http/src/uri/fmt/from_uri_param.rs
index 76052153..9caadd69 100644
--- a/core/http/src/uri/fmt/from_uri_param.rs
+++ b/core/http/src/uri/fmt/from_uri_param.rs
@@ -350,7 +350,7 @@ impl<A, T: FromUriParam<fmt::Query, A>> FromUriParam<fmt::Query, Option<A>> for
 
     #[inline(always)]
     fn from_uri_param(param: Option<A>) -> Self::Target {
-        param.map(|a| T::from_uri_param(a))
+        param.map(T::from_uri_param)
     }
 }
 
@@ -359,7 +359,7 @@ impl<A, E, T: FromUriParam<fmt::Query, A>> FromUriParam<fmt::Query, Option<A>> f
 
     #[inline(always)]
     fn from_uri_param(param: Option<A>) -> Self::Target {
-        param.map(|a| T::from_uri_param(a))
+        param.map(T::from_uri_param)
     }
 }
 
@@ -368,7 +368,7 @@ impl<A, E, T: FromUriParam<fmt::Query, A>> FromUriParam<fmt::Query, Result<A, E>
 
     #[inline(always)]
     fn from_uri_param(param: Result<A, E>) -> Self::Target {
-        param.map(|a| T::from_uri_param(a))
+        param.map(T::from_uri_param)
     }
 }
 
@@ -377,6 +377,6 @@ impl<A, E, T: FromUriParam<fmt::Query, A>> FromUriParam<fmt::Query, Result<A, E>
 
     #[inline(always)]
     fn from_uri_param(param: Result<A, E>) -> Self::Target {
-        param.map(|a| T::from_uri_param(a))
+        param.map(T::from_uri_param)
     }
 }
diff --git a/core/http/src/uri/origin.rs b/core/http/src/uri/origin.rs
index 6667567b..fa2c214e 100644
--- a/core/http/src/uri/origin.rs
+++ b/core/http/src/uri/origin.rs
@@ -323,7 +323,7 @@ impl<'a> Origin<'a> {
         where F: FnOnce(&'s RawStr) -> P, P: Into<RawStrBuf> + 's
     {
         let path = f(self.path().raw()).into();
-        if !path.starts_with('/') || !path.as_bytes().iter().all(|b| is_pchar(&b)) {
+        if !path.starts_with('/') || !path.as_bytes().iter().all(is_pchar) {
             return None;
         }
 
diff --git a/core/http/src/uri/path_query.rs b/core/http/src/uri/path_query.rs
index 93287ffa..54725709 100644
--- a/core/http/src/uri/path_query.rs
+++ b/core/http/src/uri/path_query.rs
@@ -59,7 +59,7 @@ fn decode_to_indexed_str<P: fmt::Part>(
         Cow::Borrowed(b) if indexed.is_indexed() => {
             let indexed = IndexedStr::checked_from(b, source.as_str());
             debug_assert!(indexed.is_some());
-            indexed.unwrap_or(IndexedStr::from(Cow::Borrowed("")))
+            indexed.unwrap_or_else(|| IndexedStr::from(Cow::Borrowed("")))
         }
         cow => IndexedStr::from(Cow::Owned(cow.into_owned())),
     }
@@ -77,7 +77,7 @@ impl<'a> Path<'a> {
     /// assert_eq!(uri.path().raw(), "/foo%20bar%2dbaz");
     /// ```
     pub fn raw(&self) -> &'a RawStr {
-        self.data.value.from_cow_source(&self.source).into()
+        self.data.value.from_cow_source(self.source).into()
     }
 
     /// Returns the raw, undecoded path value as an `&str`.
@@ -103,7 +103,7 @@ impl<'a> Path<'a> {
     }
 
     /// Normalizes `self`. If `absolute`, a starting  `/` is required.
-    pub(crate) fn to_normalized(&self, absolute: bool) -> Data<'static, fmt::Path> {
+    pub(crate) fn to_normalized(self, absolute: bool) -> Data<'static, fmt::Path> {
         let mut path = String::with_capacity(self.raw().len());
         let absolute = absolute || self.raw().starts_with('/');
         for (i, seg) in self.raw_segments().filter(|s| !s.is_empty()).enumerate() {
@@ -199,7 +199,7 @@ impl<'a> Query<'a> {
     /// assert_eq!(uri.query().unwrap().raw(), "baz+bar");
     /// ```
     pub fn raw(&self) -> &'a RawStr {
-        self.data.value.from_cow_source(&self.source).into()
+        self.data.value.from_cow_source(self.source).into()
     }
 
     /// Returns the raw, undecoded query value as an `&str`.
@@ -222,7 +222,7 @@ impl<'a> Query<'a> {
     }
 
     /// Normalizes `self`.
-    pub(crate) fn to_normalized(&self) -> Option<Data<'static, fmt::Query>> {
+    pub(crate) fn to_normalized(self) -> Option<Data<'static, fmt::Query>> {
         let mut query = String::with_capacity(self.raw().len());
         for (i, seg) in self.raw_segments().filter(|s| !s.is_empty()).enumerate() {
             if i != 0 { query.push('&'); }
diff --git a/core/http/src/uri/reference.rs b/core/http/src/uri/reference.rs
index 6ef6149c..a2592ee8 100644
--- a/core/http/src/uri/reference.rs
+++ b/core/http/src/uri/reference.rs
@@ -92,7 +92,7 @@ impl<'a> Reference<'a> {
         Reference {
             source: Some(as_utf8_unchecked(source)),
             scheme: scheme.map(|s| s.into()),
-            authority: authority.map(|s| s.into()),
+            authority,
             path: Data::raw(path),
             query: query.map(Data::raw),
             fragment: fragment.map(|f| f.into()),
diff --git a/core/http/src/uri/segments.rs b/core/http/src/uri/segments.rs
index 663d1d49..aad8a059 100644
--- a/core/http/src/uri/segments.rs
+++ b/core/http/src/uri/segments.rs
@@ -154,7 +154,7 @@ impl<'a> Segments<'a, Path> {
     /// assert!(b.path().segments().skip(1).prefix_of(a.path().segments()));
     /// ```
     #[inline]
-    pub fn prefix_of<'b>(self, other: Segments<'b, Path>) -> bool {
+    pub fn prefix_of(self, other: Segments<'_, Path>) -> bool {
         if self.len() > other.len() {
             return false;
         }
diff --git a/core/lib/build.rs b/core/lib/build.rs
index 7845ad2a..dd11943b 100644
--- a/core/lib/build.rs
+++ b/core/lib/build.rs
@@ -3,19 +3,19 @@
 use yansi::{Paint, Color::{Red, Yellow}};
 
 fn main() {
-    const MIN_VERSION: &'static str = "1.46.0";
+    const MIN_VERSION: &str = "1.46.0";
 
     if let Some(version) = version_check::Version::read() {
         if !version.at_least(MIN_VERSION) {
             let msg = "Rocket requires a more recent version of rustc.";
             eprintln!("{} {}", Red.paint("Error:").bold(), Paint::new(msg).bold());
-            eprintln!("Installed version: {}", Yellow.paint(format!("{}", version)));
-            eprintln!("Minimum required:  {}", Yellow.paint(format!("{}", MIN_VERSION)));
+            eprintln!("Installed version: {}", Yellow.paint(version));
+            eprintln!("Minimum required:  {}", Yellow.paint(MIN_VERSION));
             panic!("Aborting compilation due to incompatible compiler.")
         }
     } else {
-        println!("cargo:warning={}", "Rocket was unable to check rustc compiler compatibility.");
-        println!("cargo:warning={}", "Build may fail due to incompatible rustc version.");
+        println!("cargo:warning=Rocket was unable to check rustc compiler compatibility.");
+        println!("cargo:warning=Build may fail due to incompatible rustc version.");
     }
 
     if let Some(true) = version_check::is_feature_flaggable() {
diff --git a/core/lib/src/config/tls.rs b/core/lib/src/config/tls.rs
index 9010cd10..89bc7a8b 100644
--- a/core/lib/src/config/tls.rs
+++ b/core/lib/src/config/tls.rs
@@ -180,8 +180,8 @@ impl TlsConfig {
     /// ```
     pub fn from_bytes(certs: &[u8], key: &[u8]) -> Self {
         TlsConfig {
-            certs: Either::Right(certs.to_vec().into()),
-            key: Either::Right(key.to_vec().into()),
+            certs: Either::Right(certs.to_vec()),
+            key: Either::Right(key.to_vec()),
             ciphers: CipherSuite::default_set(),
             prefer_server_cipher_order: Default::default(),
         }
diff --git a/core/lib/src/cookies.rs b/core/lib/src/cookies.rs
index 72bddf92..42ce00fb 100644
--- a/core/lib/src/cookies.rs
+++ b/core/lib/src/cookies.rs
@@ -267,7 +267,7 @@ impl<'a> CookieJar<'a> {
         }
 
         drop(ops);
-        self.get(name).map(|c| c.clone())
+        self.get(name).cloned()
     }
 
     /// Retrives the _original or pending_ `Cookie` inside this collection with
@@ -448,7 +448,7 @@ impl<'a> CookieJar<'a> {
     /// TODO: This could be faster by just returning the cookies directly via
     /// an ordered hash-set of sorts.
     pub(crate) fn take_delta_jar(&self) -> cookie::CookieJar {
-        let ops = std::mem::replace(&mut *self.ops.lock(), Vec::new());
+        let ops = std::mem::take(&mut *self.ops.lock());
         let mut jar = cookie::CookieJar::new();
 
         for op in ops {
diff --git a/core/lib/src/data/limits.rs b/core/lib/src/data/limits.rs
index e942a89c..5011f4ab 100644
--- a/core/lib/src/data/limits.rs
+++ b/core/lib/src/data/limits.rs
@@ -203,7 +203,7 @@ impl Limits {
         let name = name.into();
         match self.limits.binary_search_by(|(k, _)| k.cmp(&name)) {
             Ok(i) => self.limits[i].1 = limit,
-            Err(i) => self.limits.insert(i, (name.into(), limit))
+            Err(i) => self.limits.insert(i, (name, limit))
         }
 
         self
diff --git a/core/lib/src/form/error.rs b/core/lib/src/form/error.rs
index a58ced09..f474bbcd 100644
--- a/core/lib/src/form/error.rs
+++ b/core/lib/src/form/error.rs
@@ -821,9 +821,9 @@ impl fmt::Display for ErrorKind<'_> {
                 }
             }
             ErrorKind::InvalidChoice { choices } => {
-                match choices.as_ref() {
-                    &[] => write!(f, "invalid choice")?,
-                    &[ref choice] => write!(f, "expected {}", choice)?,
+                match *choices.as_ref() {
+                    [] => write!(f, "invalid choice")?,
+                    [ref choice] => write!(f, "expected {}", choice)?,
                     _ => {
                         write!(f, "expected one of ")?;
                         for (i, choice) in choices.iter().enumerate() {
diff --git a/core/lib/src/form/name/view.rs b/core/lib/src/form/name/view.rs
index 7ddd55e5..ce3603f7 100644
--- a/core/lib/src/form/name/view.rs
+++ b/core/lib/src/form/name/view.rs
@@ -154,7 +154,7 @@ impl<'v> NameView<'v> {
     /// assert_eq!(view.key(), None);
     /// ```
     pub fn shift(&mut self) {
-        const START_DELIMS: &'static [char] = &['.', '['];
+        const START_DELIMS: &[char] = &['.', '['];
 
         let string = &self.name[self.end..];
         let bytes = string.as_bytes();
diff --git a/core/lib/src/form/parser.rs b/core/lib/src/form/parser.rs
index 20bd8430..d194dc3f 100644
--- a/core/lib/src/form/parser.rs
+++ b/core/lib/src/form/parser.rs
@@ -216,7 +216,7 @@ impl Buffer {
         }
     }
 
-    pub fn push_one<'a, S: Into<String>>(&'a self, string: S) -> &'a str {
+    pub fn push_one<S: Into<String>>(&self, string: S) -> &str {
         // SAFETY:
         //   * Aliasing: We retrieve a mutable reference to the last slot (via
         //     `push()`) and then return said reference as immutable; these
diff --git a/core/lib/src/form/validate.rs b/core/lib/src/form/validate.rs
index f5247b24..6966c2bc 100644
--- a/core/lib/src/form/validate.rs
+++ b/core/lib/src/form/validate.rs
@@ -329,7 +329,7 @@ impl<L, T: Len<L> + ?Sized> Len<L> for &T {
 }
 
 impl<L, T: Len<L>> Len<L> for Option<T> {
-    fn len(&self) -> L { self.as_ref().map(|v| v.len()).unwrap_or(T::zero_len()) }
+    fn len(&self) -> L { self.as_ref().map(|v| v.len()).unwrap_or_else(T::zero_len) }
     fn len_into_u64(len: L) -> u64 { T::len_into_u64(len) }
     fn zero_len() -> L { T::zero_len() }
 }
diff --git a/core/lib/src/fs/file_name.rs b/core/lib/src/fs/file_name.rs
index 831da79d..9654f090 100644
--- a/core/lib/src/fs/file_name.rs
+++ b/core/lib/src/fs/file_name.rs
@@ -154,7 +154,7 @@ impl FileName {
         let file_name = std::path::Path::new(&self.0)
             .file_name()
             .and_then(|n| n.to_str())
-            .and_then(|n| n.split(bad_char).filter(|s| !s.is_empty()).next())?;
+            .and_then(|n| n.split(bad_char).find(|s| !s.is_empty()))?;
 
         // At this point, `file_name` can't contain `bad_chars` because of
         // `.split()`, but it can be empty or reserved.
diff --git a/core/lib/src/fs/server.rs b/core/lib/src/fs/server.rs
index b1f11c73..282c76db 100644
--- a/core/lib/src/fs/server.rs
+++ b/core/lib/src/fs/server.rs
@@ -180,10 +180,10 @@ impl FileServer {
     }
 }
 
-impl Into<Vec<Route>> for FileServer {
-    fn into(self) -> Vec<Route> {
-        let source = figment::Source::File(self.root.clone());
-        let mut route = Route::ranked(self.rank, Method::Get, "/<path..>", self);
+impl From<FileServer> for Vec<Route> {
+    fn from(server: FileServer) -> Self {
+        let source = figment::Source::File(server.root.clone());
+        let mut route = Route::ranked(server.rank, Method::Get, "/<path..>", server);
         route.name = Some(format!("FileServer: {}", source).into());
         vec![route]
     }
diff --git a/core/lib/src/local/asynchronous/client.rs b/core/lib/src/local/asynchronous/client.rs
index bd3af563..a48350ae 100644
--- a/core/lib/src/local/asynchronous/client.rs
+++ b/core/lib/src/local/asynchronous/client.rs
@@ -60,7 +60,7 @@ impl Client {
     ) -> Result<Client, Error> {
         let rocket = rocket.local_launch().await?;
         let cookies = RwLock::new(cookie::CookieJar::new());
-        Ok(Client { rocket, tracked, cookies })
+        Ok(Client { rocket, cookies, tracked })
     }
 
     // WARNING: This is unstable! Do not use this method outside of Rocket!
diff --git a/core/lib/src/local/client.rs b/core/lib/src/local/client.rs
index 0fe73b17..d3aba814 100644
--- a/core/lib/src/local/client.rs
+++ b/core/lib/src/local/client.rs
@@ -114,7 +114,7 @@ macro_rules! pub_client_impl {
 
     /// Deprecated alias to [`Client::tracked()`].
     #[deprecated(
-        since = "0.5",
+        since = "0.5.0",
         note = "choose between `Client::untracked()` and `Client::tracked()`"
     )]
     pub $($prefix)? fn new<P: Phase>(rocket: Rocket<P>) -> Result<Self, Error> {
diff --git a/core/lib/src/request/request.rs b/core/lib/src/request/request.rs
index 43880796..d2abc4ae 100644
--- a/core/lib/src/request/request.rs
+++ b/core/lib/src/request/request.rs
@@ -47,7 +47,7 @@ impl Request<'_> {
             method: Atomic::new(self.method()),
             uri: self.uri.clone(),
             headers: self.headers.clone(),
-            remote: self.remote.clone(),
+            remote: self.remote,
             state: self.state.clone(),
         }
     }
@@ -837,12 +837,12 @@ impl<'r> Request<'r> {
     ) -> Result<Request<'r>, Error<'r>> {
         // Ensure that the method is known. TODO: Allow made-up methods?
         let method = Method::from_hyp(&hyper.method)
-            .ok_or_else(|| Error::BadMethod(&hyper.method))?;
+            .ok_or(Error::BadMethod(&hyper.method))?;
 
         // In debug, make sure we agree with Hyper. Otherwise, cross our fingers
         // and trust that it only gives us valid URIs like it's supposed to.
         // TODO: Keep around not just the path/query, but the rest, if there?
-        let uri = hyper.uri.path_and_query().ok_or_else(|| Error::InvalidUri(&hyper.uri))?;
+        let uri = hyper.uri.path_and_query().ok_or(Error::InvalidUri(&hyper.uri))?;
         debug_assert!(Origin::parse(uri.as_str()).is_ok());
         let uri = Origin::new(uri.path(), uri.query().map(Cow::Borrowed));
 
diff --git a/core/lib/src/response/body.rs b/core/lib/src/response/body.rs
index 2c45bb1c..77416371 100644
--- a/core/lib/src/response/body.rs
+++ b/core/lib/src/response/body.rs
@@ -132,7 +132,7 @@ impl<'r> Body<'r> {
     }
 
     pub(crate) fn strip(&mut self) {
-        let body = std::mem::replace(self, Body::default());
+        let body = std::mem::take(self);
         *self = match body.inner {
             Inner::Seekable(b) | Inner::Phantom(b) => Body {
                 size: body.size,
@@ -322,7 +322,7 @@ impl<'r> Body<'r> {
     /// ```
     #[inline(always)]
     pub fn take(&mut self) -> Self {
-        std::mem::replace(self, Body::default())
+        std::mem::take(self)
     }
 
     /// Reads all of `self` into a vector of bytes, consuming the contents.
diff --git a/core/lib/src/response/stream/sse.rs b/core/lib/src/response/stream/sse.rs
index d69bacf4..c2c397e5 100644
--- a/core/lib/src/response/stream/sse.rs
+++ b/core/lib/src/response/stream/sse.rs
@@ -337,7 +337,7 @@ impl Event {
             Some(RawLinedEvent::raw("")),
         ];
 
-        stream::iter(array::IntoIter::new(events)).filter_map(|v| ready(v))
+        stream::iter(array::IntoIter::new(events)).filter_map(ready)
     }
 }
 
diff --git a/core/lib/src/rocket.rs b/core/lib/src/rocket.rs
index 9142e142..94b4f920 100644
--- a/core/lib/src/rocket.rs
+++ b/core/lib/src/rocket.rs
@@ -488,7 +488,7 @@ impl Rocket<Build> {
 
             if config.secret_key.is_zero() {
                 config.secret_key = crate::config::SecretKey::generate()
-                    .unwrap_or(crate::config::SecretKey::zero());
+                    .unwrap_or_else(crate::config::SecretKey::zero);
             }
         };
 
diff --git a/core/lib/src/route/uri.rs b/core/lib/src/route/uri.rs
index 656f0f4c..b8e00a9a 100644
--- a/core/lib/src/route/uri.rs
+++ b/core/lib/src/route/uri.rs
@@ -123,7 +123,7 @@ impl<'a> RouteUri<'a> {
         let source = origin.to_string().into();
         let metadata = Metadata::from(&base, &origin);
 
-        Ok(RouteUri { source, unmounted_origin, base, origin, metadata })
+        Ok(RouteUri { source, base, unmounted_origin, origin, metadata })
     }
 
     /// Create a new `RouteUri`.
@@ -287,8 +287,8 @@ impl Metadata {
         let trailing_path = path_segs.last().map_or(false, |p| p.trailing);
 
         Metadata {
-            static_query_fields, path_color, query_color, trailing_path,
-            path_segs, query_segs, base_segs,
+            base_segs, path_segs, query_segs, static_query_fields,
+            path_color, query_color, trailing_path,
         }
     }
 }
diff --git a/core/lib/src/server.rs b/core/lib/src/server.rs
index 0e5c9065..e8ac5ebe 100644
--- a/core/lib/src/server.rs
+++ b/core/lib/src/server.rs
@@ -279,7 +279,7 @@ impl Rocket<Orbit> {
 
             let name = route.name.as_deref();
             let outcome = handle(name, || route.handler.handle(request, data)).await
-                .unwrap_or_else(|| Outcome::Failure(Status::InternalServerError));
+                .unwrap_or(Outcome::Failure(Status::InternalServerError));
 
             // Check if the request processing completed (Some) or if the
             // request needs to be forwarded. If it does, continue the loop
diff --git a/core/lib/src/shield/policy.rs b/core/lib/src/shield/policy.rs
index d0a88b12..f0418e8f 100644
--- a/core/lib/src/shield/policy.rs
+++ b/core/lib/src/shield/policy.rs
@@ -156,9 +156,9 @@ impl Default for Referrer {
     }
 }
 
-impl Into<Header<'static>> for &Referrer {
-    fn into(self) -> Header<'static> {
-        let policy_string = match self {
+impl From<&Referrer> for Header<'static> {
+    fn from(referrer: &Referrer) -> Self {
+        let policy_string = match referrer {
             Referrer::NoReferrer => "no-referrer",
             Referrer::NoReferrerWhenDowngrade => "no-referrer-when-downgrade",
             Referrer::Origin => "origin",
@@ -217,9 +217,9 @@ impl Default for ExpectCt {
     }
 }
 
-impl Into<Header<'static>> for &ExpectCt {
-    fn into(self) -> Header<'static> {
-        let policy_string =  match self {
+impl From<&ExpectCt> for Header<'static> {
+    fn from(expect: &ExpectCt) -> Self {
+        let policy_string =  match expect {
             ExpectCt::Enforce(age) => format!("max-age={}, enforce", age.whole_seconds()),
             ExpectCt::Report(age, uri) => {
                 format!(r#"max-age={}, report-uri="{}""#, age.whole_seconds(), uri)
@@ -251,8 +251,8 @@ impl Default for NoSniff {
     }
 }
 
-impl Into<Header<'static>> for &NoSniff {
-    fn into(self) -> Header<'static> {
+impl From<&NoSniff> for Header<'static> {
+    fn from(_: &NoSniff) -> Self {
         Header::new(NoSniff::NAME, "nosniff")
     }
 }
@@ -301,9 +301,9 @@ impl Default for Hsts {
     }
 }
 
-impl Into<Header<'static>> for &Hsts {
-    fn into(self) -> Header<'static> {
-        if self == &Hsts::default() {
+impl From<&Hsts> for Header<'static> {
+    fn from(hsts: &Hsts) -> Self {
+        if hsts == &Hsts::default() {
             static DEFAULT: Header<'static> = Header {
                 name: Uncased::from_borrowed(Hsts::NAME),
                 value: Cow::Borrowed("max-age=31536000")
@@ -312,7 +312,7 @@ impl Into<Header<'static>> for &Hsts {
             return DEFAULT.clone();
         }
 
-        let policy_string = match self {
+        let policy_string = match hsts {
             Hsts::Enable(age) => format!("max-age={}", age.whole_seconds()),
             Hsts::IncludeSubDomains(age) => {
                 format!("max-age={}; includeSubDomains", age.whole_seconds())
@@ -353,9 +353,9 @@ impl Default for Frame {
     }
 }
 
-impl Into<Header<'static>> for &Frame {
-    fn into(self) -> Header<'static> {
-        let policy_string: &'static str = match self {
+impl From<&Frame> for Header<'static> {
+    fn from(frame: &Frame) -> Self {
+        let policy_string: &'static str = match frame {
             Frame::Deny => "DENY",
             Frame::SameOrigin => "SAMEORIGIN",
         };
@@ -389,9 +389,9 @@ impl Default for XssFilter {
     }
 }
 
-impl Into<Header<'static>> for &XssFilter {
-    fn into(self) -> Header<'static> {
-        let policy_string: &'static str = match self {
+impl From<&XssFilter> for Header<'static> {
+    fn from(filter: &XssFilter) -> Self {
+        let policy_string: &'static str = match filter {
             XssFilter::Disable => "0",
             XssFilter::Enable => "1",
             XssFilter::EnableBlock => "1; mode=block",
@@ -423,9 +423,9 @@ impl Default for Prefetch {
     }
 }
 
-impl Into<Header<'static>> for &Prefetch {
-    fn into(self) -> Header<'static> {
-        let policy_string = match self {
+impl From<&Prefetch> for Header<'static> {
+    fn from(prefetch: &Prefetch) -> Self {
+        let policy_string = match prefetch {
             Prefetch::On => "on",
             Prefetch::Off => "off",
         };
@@ -645,9 +645,9 @@ impl Permission {
     }
 }
 
-impl Into<Header<'static>> for &Permission {
-    fn into(self) -> Header<'static> {
-        if self == &Permission::default() {
+impl From<&Permission> for Header<'static> {
+    fn from(perm: &Permission) -> Self {
+        if perm == &Permission::default() {
             static DEFAULT: Header<'static> = Header {
                 name: Uncased::from_borrowed(Permission::NAME),
                 value: Cow::Borrowed("interest-cohort=()")
@@ -656,7 +656,7 @@ impl Into<Header<'static>> for &Permission {
             return DEFAULT.clone();
         }
 
-        let value = self.0.iter()
+        let value = perm.0.iter()
             .map(|(feature, allow)| {
                 let list = allow.as_ref()
                     .into_iter()
diff --git a/examples/manual-routing/src/main.rs b/examples/manual-routing/src/main.rs
index f0d4e623..69e03a1b 100644
--- a/examples/manual-routing/src/main.rs
+++ b/examples/manual-routing/src/main.rs
@@ -73,7 +73,7 @@ struct CustomHandler {
 }
 
 impl CustomHandler {
-    fn new(data: &'static str) -> Vec<Route> {
+    fn routes(data: &'static str) -> Vec<Route> {
         vec![Route::new(Get, "/<id>", Self { data })]
     }
 }
@@ -107,6 +107,6 @@ fn rocket() -> _ {
         .mount("/upload", vec![get_upload, post_upload])
         .mount("/hello", vec![name.clone()])
         .mount("/hi", vec![name])
-        .mount("/custom", CustomHandler::new("some data here"))
+        .mount("/custom", CustomHandler::routes("some data here"))
         .register("/", vec![not_found_catcher])
 }