Remove allow(unused) in favor of cfg guards

src/data.rs

@@ -4,7 +4,9 @@ mod field;
 mod fields;
 
 use proc_macro2::Span;
-use syn::{Expr, FieldsNamed, Ident, Pat, PatPath, Path, Result, Variant};
+#[cfg(not(feature = "nightly"))]
+use syn::Expr;
+use syn::{FieldsNamed, Ident, Pat, PatPath, Path, Result, Variant};
 
 pub use self::{
 	field::{Field, Member},
@@ -27,7 +29,7 @@ pub struct Data<'a> {
 	pub path: Path,
 	/// [Type](DataType) of this struct, union or variant.
 	pub type_: DataType<'a>,
-	#[cfg_attr(feature = "nightly", allow(unused))]
+	#[cfg(not(feature = "nightly"))]
 	/// Discriminant of this variant.
 	pub discriminant: Option<&'a Expr>,
 }
@@ -70,7 +72,7 @@ pub enum SimpleType<'a> {
 	/// Tuple struct or tuple variant.
 	Tuple(&'a Fields<'a>),
 	/// Union.
-	Union(#[allow(unused)] &'a Fields<'a>),
+	Union,
 	/// Unit variant.
 	Unit(&'a Pat),
 }
@@ -101,6 +103,7 @@ impl<'a> Data<'a> {
 						ident,
 						path,
 						type_: DataType::Struct(fields),
+						#[cfg(not(feature = "nightly"))]
 						discriminant: None,
 					})
 				}
@@ -118,6 +121,7 @@ impl<'a> Data<'a> {
 						ident,
 						path,
 						type_: DataType::Tuple(fields),
+						#[cfg(not(feature = "nightly"))]
 						discriminant: None,
 					})
 				}
@@ -132,6 +136,7 @@ impl<'a> Data<'a> {
 					qself: None,
 					path,
 				})),
+				#[cfg(not(feature = "nightly"))]
 				discriminant: None,
 			}),
 			syn::Fields::Unit => Err(Error::item_empty(span)),
@@ -159,6 +164,7 @@ impl<'a> Data<'a> {
 				ident,
 				path,
 				type_: DataType::Union(fields),
+				#[cfg(not(feature = "nightly"))]
 				discriminant: None,
 			})
 		}
@@ -192,6 +198,7 @@ impl<'a> Data<'a> {
 						default,
 						type_: VariantType::Struct(fields),
 					},
+					#[cfg(not(feature = "nightly"))]
 					discriminant: variant.discriminant.as_ref().map(|(_, expr)| expr),
 				})
 			}
@@ -208,6 +215,7 @@ impl<'a> Data<'a> {
 						default,
 						type_: VariantType::Tuple(fields),
 					},
+					#[cfg(not(feature = "nightly"))]
 					discriminant: variant.discriminant.as_ref().map(|(_, expr)| expr),
 				})
 			}
@@ -227,6 +235,7 @@ impl<'a> Data<'a> {
 						default,
 						type_: VariantType::Unit(pattern),
 					},
+					#[cfg(not(feature = "nightly"))]
 					discriminant: variant.discriminant.as_ref().map(|(_, expr)| expr),
 				})
 			}
@@ -328,7 +337,7 @@ impl<'a> Data<'a> {
 				type_: VariantType::Unit(pattern),
 				..
 			} => SimpleType::Unit(pattern),
-			DataType::Union(fields) => SimpleType::Union(fields),
+			DataType::Union(_) => SimpleType::Union,
 		}
 	}
 

src/error.rs

@@ -213,12 +213,14 @@ impl Error {
 	}
 
 	/// Unknown `repr`.
+	#[cfg(not(feature = "nightly"))]
 	pub fn repr_unknown(span: Span) -> syn::Error {
 		syn::Error::new(span, "found unknown representation")
 	}
 
 	/// Invalid enum with non-empty variants and custom discriminants without an
 	/// integer representation.
+	#[cfg(not(feature = "nightly"))]
 	pub fn repr_discriminant_invalid(span: Span) -> syn::Error {
 		syn::Error::new(
 			span,

src/input.rs

@@ -5,7 +5,9 @@ use syn::{DeriveInput, GenericParam, Generics, ImplGenerics, Result, TypeGeneric
 
 #[cfg(feature = "zeroize")]
 use crate::DeriveTrait;
-use crate::{Data, DeriveWhere, Discriminant, Either, Error, Item, ItemAttr, Trait};
+#[cfg(not(feature = "nightly"))]
+use crate::Discriminant;
+use crate::{Data, DeriveWhere, Either, Error, Item, ItemAttr, Trait};
 
 /// Parsed input.
 pub struct Input<'a> {
@@ -51,6 +53,7 @@ impl<'a> Input<'a> {
 			)
 			.map(Item::Item)?,
 			syn::Data::Enum(data) => {
+				#[cfg(not(feature = "nightly"))]
 				let discriminant = Discriminant::parse(attrs, &data.variants)?;
 
 				let variants = data
@@ -99,6 +102,7 @@ impl<'a> Input<'a> {
 				}
 
 				Item::Enum {
+					#[cfg(not(feature = "nightly"))]
 					discriminant,
 					ident,
 					variants,

src/item.rs

@@ -1,18 +1,24 @@
 //! Intermediate representation of item data.
 
-use proc_macro2::{Ident, Span, TokenStream, TokenTree};
-use quote::ToTokens;
-use syn::{punctuated::Punctuated, spanned::Spanned, Attribute, Meta, Result, Token, Variant};
+use proc_macro2::Ident;
+#[cfg(not(feature = "nightly"))]
+use {
+	proc_macro2::{Span, TokenStream, TokenTree},
+	quote::ToTokens,
+	syn::{punctuated::Punctuated, spanned::Spanned, Attribute, Meta, Result, Token, Variant},
+};
 
-use crate::{Data, Error, Incomparable, Trait};
+#[cfg(not(feature = "nightly"))]
+use crate::Error;
+use crate::{Data, Incomparable, Trait};
 
 /// Fields or variants of an item.
 #[cfg_attr(test, derive(Debug))]
 #[allow(clippy::large_enum_variant)]
 pub enum Item<'a> {
 	/// Enum.
 	Enum {
-		#[cfg_attr(feature = "nightly", allow(unused))]
+		#[cfg(not(feature = "nightly"))]
 		/// Type of discriminant used.
 		discriminant: Discriminant,
 		/// [`struct@Ident`] of this enum.
@@ -97,7 +103,7 @@ impl Item<'_> {
 /// Type of discriminant used.
 #[derive(Clone, Copy)]
 #[cfg_attr(test, derive(Debug))]
-#[cfg_attr(feature = "nightly", allow(unused))]
+#[cfg(not(feature = "nightly"))]
 pub enum Discriminant {
 	/// The enum has only a single variant.
 	Single,
@@ -111,6 +117,7 @@ pub enum Discriminant {
 	DataRepr(Representation),
 }
 
+#[cfg(not(feature = "nightly"))]
 impl Discriminant {
 	/// Parse the representation of an item.
 	pub fn parse(attrs: &[Attribute], variants: &Punctuated<Variant, Token![,]>) -> Result<Self> {
@@ -167,6 +174,7 @@ impl Discriminant {
 /// The type used to represent an enum.
 #[derive(Clone, Copy)]
 #[cfg_attr(test, derive(Debug))]
+#[cfg(not(feature = "nightly"))]
 pub enum Representation {
 	/// [`u8`].
 	U8,
@@ -194,6 +202,7 @@ pub enum Representation {
 	ISize,
 }
 
+#[cfg(not(feature = "nightly"))]
 impl Representation {
 	/// Parse an [`struct@Ident`] to a valid representation if it is.
 	fn parse(ident: &Ident) -> Option<Self> {
@@ -247,6 +256,7 @@ impl Representation {
 	}
 }
 
+#[cfg(not(feature = "nightly"))]
 impl ToTokens for Representation {
 	fn to_tokens(&self, tokens: &mut TokenStream) {
 		tokens.extend(self.to_token());

src/lib.rs

@@ -408,6 +408,8 @@ use util::MetaListExt;
 
 #[cfg(feature = "zeroize")]
 use self::attr::ZeroizeFqs;
+#[cfg(not(feature = "nightly"))]
+use self::item::Discriminant;
 use self::{
 	attr::{
 		Default, DeriveTrait, DeriveWhere, FieldAttr, Incomparable, ItemAttr, Skip, SkipGroup,
@@ -416,7 +418,7 @@ use self::{
 	data::{Data, DataType, Field, SimpleType},
 	error::Error,
 	input::Input,
-	item::{Discriminant, Item},
+	item::Item,
 	trait_::{Trait, TraitImpl},
 	util::Either,
 };

src/trait_/clone.rs

@@ -123,7 +123,7 @@ impl TraitImpl for Clone {
 			SimpleType::Unit(pattern) => {
 				quote! { #pattern => #pattern, }
 			}
-			SimpleType::Union(_) => TokenStream::new(),
+			SimpleType::Union => TokenStream::new(),
 		}
 	}
 }

src/trait_/common_ord.rs

@@ -461,7 +461,7 @@ pub fn build_incomparable_pattern(variants: &[Data]) -> Option<TokenStream> {
 		.map(|variant @ Data { path, .. }| match variant.simple_type() {
 			SimpleType::Struct(_) => quote!(#path{..}),
 			SimpleType::Tuple(_) => quote!(#path(..)),
-			SimpleType::Union(_) => unreachable!("enum variants cannot be unions"),
+			SimpleType::Union => unreachable!("enum variants cannot be unions"),
 			SimpleType::Unit(_) => quote!(#path),
 		})
 		.peekable();

src/trait_/debug.rs

@@ -79,7 +79,7 @@ impl TraitImpl for Debug {
 			SimpleType::Unit(_) => {
 				quote! { #self_pattern => ::core::fmt::Formatter::write_str(__f, #debug_name), }
 			}
-			SimpleType::Union(_) => unreachable!("unexpected trait for union"),
+			SimpleType::Union => unreachable!("unexpected trait for union"),
 		}
 	}
 }

src/trait_/default.rs

@@ -60,7 +60,7 @@ impl TraitImpl for Default {
 				SimpleType::Unit(_) => {
 					quote! { #path }
 				}
-				SimpleType::Union(_) => unreachable!("unexpected trait for union"),
+				SimpleType::Union => unreachable!("unexpected trait for union"),
 			}
 		}
 		// Skip `Default` implementation if variant isn't marked with a `default` attribute.

src/trait_/hash.rs

@@ -69,7 +69,7 @@ impl TraitImpl for Hash {
 					}
 				}
 			}
-			SimpleType::Union(_) => unreachable!("unexpected trait for union"),
+			SimpleType::Union => unreachable!("unexpected trait for union"),
 		}
 	}
 }

src/trait_/ord.rs

@@ -57,7 +57,7 @@ impl TraitImpl for Ord {
 					}
 				}
 				SimpleType::Unit(_) => TokenStream::new(),
-				SimpleType::Union(_) => unreachable!("unexpected trait for union"),
+				SimpleType::Union => unreachable!("unexpected trait for union"),
 			}
 		}
 	}

src/trait_/partial_eq.rs

@@ -127,7 +127,7 @@ impl TraitImpl for PartialEq {
 					}
 				}
 				SimpleType::Unit(_) => TokenStream::new(),
-				SimpleType::Union(_) => unreachable!("unexpected trait for union"),
+				SimpleType::Union => unreachable!("unexpected trait for union"),
 			}
 		}
 	}

src/trait_/partial_ord.rs

@@ -69,7 +69,7 @@ impl TraitImpl for PartialOrd {
 					}
 				}
 				SimpleType::Unit(_) => TokenStream::new(),
-				SimpleType::Union(_) => unreachable!("unexpected trait for union"),
+				SimpleType::Union => unreachable!("unexpected trait for union"),
 			}
 		}
 	}

src/trait_/zeroize.rs

@@ -138,7 +138,7 @@ impl TraitImpl for Zeroize {
 					}
 				}
 				SimpleType::Unit(_) => TokenStream::new(),
-				SimpleType::Union(_) => unreachable!("unexpected trait for union"),
+				SimpleType::Union => unreachable!("unexpected trait for union"),
 			}
 		}
 	}

src/trait_/zeroize_on_drop.rs

@@ -169,7 +169,7 @@ impl TraitImpl for ZeroizeOnDrop {
 					}
 				}
 				SimpleType::Unit(_) => TokenStream::new(),
-				SimpleType::Union(_) => unreachable!("unexpected trait for union"),
+				SimpleType::Union => unreachable!("unexpected trait for union"),
 			}
 		}
 	}