style(prometheus-client-derive): fix rustfmt and clippy reports

Author: ADD-SP

prometheus-client-derive/src/registrant/attribute.rs

@@ -1,29 +1,19 @@
+use proc_macro2::Span;
 use quote::ToTokens;
 use syn::spanned::Spanned;
-use proc_macro2::Span;
 
 // do not derive debug since this needs "extra-traits"
 // feature for crate `syn`, which slows compile time
 // too much, and is not needed as this struct is not
 // public.
+#[derive(Default)]
 pub struct Attribute {
     pub help: Option<syn::LitStr>,
     pub unit: Option<syn::LitStr>,
     pub rename: Option<syn::LitStr>,
     pub skip: bool,
 }
 
-impl Default for Attribute {
-    fn default() -> Self {
-        Attribute {
-            help: None,
-            unit: None,
-            rename: None,
-            skip: false,
-        }
-    }
-}
-
 impl Attribute {
     fn with_help(mut self, doc: syn::LitStr) -> Self {
         self.help = Some(doc);
@@ -39,10 +29,11 @@ impl Attribute {
             let mut acc = merged
                 .help
                 .unwrap_or_else(|| syn::LitStr::new("", doc.span()))
-                .value().trim()
+                .value()
+                .trim()
                 .to_string();
             acc.push(' ');
-            acc.push_str(&doc.value().trim());
+            acc.push_str(doc.value().trim());
             merged.help = Some(syn::LitStr::new(&acc, Span::call_site()));
         }
         if let Some(unit) = other.unit {
@@ -82,12 +73,12 @@ impl syn::parse::Parse for Attribute {
             syn::Meta::NameValue(meta) if meta.path.is_ident("doc") => {
                 if let syn::Expr::Lit(lit) = meta.value {
                     let lit_str = syn::parse2::<syn::LitStr>(lit.lit.to_token_stream())?;
-                    return Ok(Attribute::default().with_help(lit_str));
+                    Ok(Attribute::default().with_help(lit_str))
                 } else {
-                    return Err(syn::Error::new_spanned(
+                    Err(syn::Error::new_spanned(
                         meta.value,
                         "Expected a string literal for doc attribute",
-                    ));
+                    ))
                 }
             }
             syn::Meta::List(meta) if meta.path.is_ident("registrant") => {
@@ -135,12 +126,10 @@ impl syn::parse::Parse for Attribute {
                 })?;
                 Ok(attr)
             }
-            _ => {
-                return Err(syn::Error::new(
-                    span,
-                    r#"Unknown attribute, expected `#[doc(...)]` or `#[registrant(<key>[=value], ...)]`"#,
-                ))
-            }
+            _ => Err(syn::Error::new(
+                span,
+                r#"Unknown attribute, expected `#[doc(...)]` or `#[registrant(<key>[=value], ...)]`"#,
+            )),
         }
     }
 }

prometheus-client-derive/src/registrant/field.rs

@@ -1,6 +1,6 @@
-use quote::ToTokens;
-use crate::registrant::attribute;
 use super::attribute::Attribute;
+use crate::registrant::attribute;
+use quote::ToTokens;
 
 // do not derive debug since this needs "extra-traits"
 // feature for crate `syn`, which slows compile time
@@ -25,13 +25,10 @@ impl Field {
     }
 
     pub(super) fn help(&self) -> syn::LitStr {
-        self.attr.help.clone()
-            .unwrap_or_else(|| {
-                syn::LitStr::new(
-                    "",
-                    self.ident.span(),
-                )
-            })
+        self.attr
+            .help
+            .clone()
+            .unwrap_or_else(|| syn::LitStr::new("", self.ident.span()))
     }
 
     pub(super) fn unit(&self) -> Option<&syn::LitStr> {
@@ -47,28 +44,22 @@ impl TryFrom<syn::Field> for Field {
     type Error = syn::Error;
 
     fn try_from(field: syn::Field) -> Result<Self, Self::Error> {
-        let ident = field.ident.clone().expect("Fields::Named should have an identifier");
-        let name = syn::LitStr::new(
-            &ident.to_string(),
-            ident.span(),
-        );
+        let ident = field
+            .ident
+            .clone()
+            .expect("Fields::Named should have an identifier");
+        let name = syn::LitStr::new(&ident.to_string(), ident.span());
         let attr = field
             .attrs
             .into_iter()
             // ignore unknown attributes, which might be defined by another derive macros.
-            .filter(|attr| attr.path().is_ident("doc") || attr.path().is_ident("registrant") )
+            .filter(|attr| attr.path().is_ident("doc") || attr.path().is_ident("registrant"))
             .try_fold(vec![], |mut acc, attr| {
                 acc.push(syn::parse2::<Attribute>(attr.meta.into_token_stream())?);
                 Ok::<Vec<attribute::Attribute>, syn::Error>(acc)
             })?
             .into_iter()
-            .try_fold(Attribute::default(), |acc, attr| {
-                acc.merge(attr)
-            })?;
-        Ok(Field{
-            ident,
-            name,
-            attr,
-        })
+            .try_fold(Attribute::default(), |acc, attr| acc.merge(attr))?;
+        Ok(Field { ident, name, attr })
     }
 }