Fix warnings introduced in newer Rust Nightly

This does not (yet) upgrade ./rust-toolchain

The warnings:

* dead_code "field is never read"
* redundant_semicolons "unnecessary trailing semicolon"
* non_fmt_panic "panic message is not a string literal, this is no longer accepted in Rust 2021"
* unstable_name_collisions "a method with this name may be added to the standard library in the future"
* legacy_derive_helpers "derive helper attribute is used before it is introduced" https://github.com/rust-lang/rust/issues/79202

components/style_derive/animate.rs

@@ -112,14 +112,14 @@ fn derive_variant_arm(
     }
 }
 
-#[darling(attributes(animation), default)]
 #[derive(Default, FromDeriveInput)]
+#[darling(attributes(animation), default)]
 pub struct AnimationInputAttrs {
     pub no_bound: Option<PathList>,
 }
 
-#[darling(attributes(animation), default)]
 #[derive(Default, FromVariant)]
+#[darling(attributes(animation), default)]
 pub struct AnimationVariantAttrs {
     pub error: bool,
     // Only here because of structs, where the struct definition acts as a
@@ -127,8 +127,8 @@ pub struct AnimationVariantAttrs {
     pub no_bound: Option<PathList>,
 }
 
-#[darling(attributes(animation), default)]
 #[derive(Default, FromField)]
+#[darling(attributes(animation), default)]
 pub struct AnimationFieldAttrs {
     pub constant: bool,
     pub field_bound: bool,

components/style_derive/compute_squared_distance.rs

@@ -118,8 +118,8 @@ fn derive_variant_arm(
     };
 }
 
-#[darling(attributes(distance), default)]
 #[derive(Default, FromField)]
+#[darling(attributes(distance), default)]
 struct DistanceFieldAttrs {
     field_bound: bool,
 }

components/style_derive/parse.rs

@@ -8,15 +8,15 @@ use proc_macro2::TokenStream;
 use syn::{self, DeriveInput, Path};
 use synstructure::{Structure, VariantInfo};
 
-#[darling(attributes(parse), default)]
 #[derive(Default, FromVariant)]
+#[darling(attributes(parse), default)]
 pub struct ParseVariantAttrs {
     pub aliases: Option<String>,
     pub condition: Option<Path>,
 }
 
-#[darling(attributes(parse), default)]
 #[derive(Default, FromField)]
+#[darling(attributes(parse), default)]
 pub struct ParseFieldAttrs {
     field_bound: bool,
 }

components/style_derive/specified_value_info.rs

@@ -166,22 +166,22 @@ fn derive_struct_fields<'a>(
     true
 }
 
-#[darling(attributes(value_info), default)]
 #[derive(Default, FromDeriveInput)]
+#[darling(attributes(value_info), default)]
 struct ValueInfoInputAttrs {
     ty: Option<Ident>,
     other_values: Option<String>,
 }
 
-#[darling(attributes(value_info), default)]
 #[derive(Default, FromVariant)]
+#[darling(attributes(value_info), default)]
 struct ValueInfoVariantAttrs {
     starts_with_keyword: bool,
     other_values: Option<String>,
 }
 
-#[darling(attributes(value_info), default)]
 #[derive(Default, FromField)]
+#[darling(attributes(value_info), default)]
 struct ValueInfoFieldAttrs {
     other_values: Option<String>,
 }

components/style_derive/to_computed_value.rs

@@ -195,8 +195,8 @@ pub struct ToValueAttrs {
     pub no_field_bound: bool,
 }
 
-#[darling(attributes(compute), default)]
 #[derive(Default, FromField)]
+#[darling(attributes(compute), default)]
 struct ComputedValueAttrs {
     field_bound: bool,
     no_field_bound: bool,

components/style_derive/to_css.rs

@@ -236,8 +236,8 @@ fn derive_single_field_expr(
     expr
 }
 
-#[darling(attributes(css), default)]
 #[derive(Default, FromDeriveInput)]
+#[darling(attributes(css), default)]
 pub struct CssInputAttrs {
     pub derive_debug: bool,
     // Here because structs variants are also their whole type definition.
@@ -246,8 +246,8 @@ pub struct CssInputAttrs {
     pub comma: bool,
 }
 
-#[darling(attributes(css), default)]
 #[derive(Default, FromVariant)]
+#[darling(attributes(css), default)]
 pub struct CssVariantAttrs {
     pub function: Option<Override<String>>,
     // Here because structs variants are also their whole type definition.
@@ -258,8 +258,8 @@ pub struct CssVariantAttrs {
     pub skip: bool,
 }
 
-#[darling(attributes(css), default)]
 #[derive(Default, FromField)]
+#[darling(attributes(css), default)]
 pub struct CssFieldAttrs {
     pub if_empty: Option<String>,
     pub field_bound: bool,

components/style_derive/to_resolved_value.rs

@@ -44,8 +44,8 @@ pub fn derive(input: DeriveInput) -> TokenStream {
     )
 }
 
-#[darling(attributes(resolve), default)]
 #[derive(Default, FromField)]
+#[darling(attributes(resolve), default)]
 struct ResolvedValueAttrs {
     field_bound: bool,
     no_field_bound: bool,