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Diffstat (limited to 'syn/tests/test_generics.rs')
| -rw-r--r-- | syn/tests/test_generics.rs | 285 |
1 files changed, 285 insertions, 0 deletions
diff --git a/syn/tests/test_generics.rs b/syn/tests/test_generics.rs new file mode 100644 index 0000000..e863b77 --- /dev/null +++ b/syn/tests/test_generics.rs @@ -0,0 +1,285 @@ +mod features; + +#[macro_use] +mod macros; + +use quote::quote; +use syn::{DeriveInput, ItemFn, TypeParamBound, WhereClause, WherePredicate}; + +#[test] +fn test_split_for_impl() { + let input = quote! { + struct S<'a, 'b: 'a, #[may_dangle] T: 'a = ()> where T: Debug; + }; + + snapshot!(input as DeriveInput, @r###" + DeriveInput { + vis: Inherited, + ident: "S", + generics: Generics { + lt_token: Some, + params: [ + Lifetime(LifetimeDef { + lifetime: Lifetime { + ident: "a", + }, + }), + Lifetime(LifetimeDef { + lifetime: Lifetime { + ident: "b", + }, + colon_token: Some, + bounds: [ + Lifetime { + ident: "a", + }, + ], + }), + Type(TypeParam { + attrs: [ + Attribute { + style: Outer, + path: Path { + segments: [ + PathSegment { + ident: "may_dangle", + arguments: None, + }, + ], + }, + tokens: ``, + }, + ], + ident: "T", + colon_token: Some, + bounds: [ + Lifetime(Lifetime { + ident: "a", + }), + ], + eq_token: Some, + default: Some(Type::Tuple), + }), + ], + gt_token: Some, + where_clause: Some(WhereClause { + predicates: [ + Type(PredicateType { + bounded_ty: Type::Path { + path: Path { + segments: [ + PathSegment { + ident: "T", + arguments: None, + }, + ], + }, + }, + bounds: [ + Trait(TraitBound { + modifier: None, + path: Path { + segments: [ + PathSegment { + ident: "Debug", + arguments: None, + }, + ], + }, + }), + ], + }), + ], + }), + }, + data: Data::Struct { + fields: Unit, + semi_token: Some, + }, + } + "###); + + let generics = input.generics; + let (impl_generics, ty_generics, where_clause) = generics.split_for_impl(); + + let generated = quote! { + impl #impl_generics MyTrait for Test #ty_generics #where_clause {} + }; + let expected = quote! { + impl<'a, 'b: 'a, #[may_dangle] T: 'a> MyTrait + for Test<'a, 'b, T> + where + T: Debug + {} + }; + assert_eq!(generated.to_string(), expected.to_string()); + + let turbofish = ty_generics.as_turbofish(); + let generated = quote! { + Test #turbofish + }; + let expected = quote! { + Test::<'a, 'b, T> + }; + assert_eq!(generated.to_string(), expected.to_string()); +} + +#[test] +fn test_ty_param_bound() { + let tokens = quote!('a); + snapshot!(tokens as TypeParamBound, @r###" + Lifetime(Lifetime { + ident: "a", + }) + "###); + + let tokens = quote!('_); + snapshot!(tokens as TypeParamBound, @r###" + Lifetime(Lifetime { + ident: "_", + }) + "###); + + let tokens = quote!(Debug); + snapshot!(tokens as TypeParamBound, @r###" + Trait(TraitBound { + modifier: None, + path: Path { + segments: [ + PathSegment { + ident: "Debug", + arguments: None, + }, + ], + }, + }) + "###); + + let tokens = quote!(?Sized); + snapshot!(tokens as TypeParamBound, @r###" + Trait(TraitBound { + modifier: Maybe, + path: Path { + segments: [ + PathSegment { + ident: "Sized", + arguments: None, + }, + ], + }, + }) + "###); +} + +#[test] +fn test_fn_precedence_in_where_clause() { + // This should parse as two separate bounds, `FnOnce() -> i32` and `Send` - not + // `FnOnce() -> (i32 + Send)`. + let input = quote! { + fn f<G>() + where + G: FnOnce() -> i32 + Send, + { + } + }; + + snapshot!(input as ItemFn, @r###" + ItemFn { + vis: Inherited, + sig: Signature { + ident: "f", + generics: Generics { + lt_token: Some, + params: [ + Type(TypeParam { + ident: "G", + }), + ], + gt_token: Some, + where_clause: Some(WhereClause { + predicates: [ + Type(PredicateType { + bounded_ty: Type::Path { + path: Path { + segments: [ + PathSegment { + ident: "G", + arguments: None, + }, + ], + }, + }, + bounds: [ + Trait(TraitBound { + modifier: None, + path: Path { + segments: [ + PathSegment { + ident: "FnOnce", + arguments: PathArguments::Parenthesized { + output: Type( + Type::Path { + path: Path { + segments: [ + PathSegment { + ident: "i32", + arguments: None, + }, + ], + }, + }, + ), + }, + }, + ], + }, + }), + Trait(TraitBound { + modifier: None, + path: Path { + segments: [ + PathSegment { + ident: "Send", + arguments: None, + }, + ], + }, + }), + ], + }), + ], + }), + }, + output: Default, + }, + block: Block, + } + "###); + + let where_clause = input.sig.generics.where_clause.as_ref().unwrap(); + assert_eq!(where_clause.predicates.len(), 1); + + let predicate = match &where_clause.predicates[0] { + WherePredicate::Type(pred) => pred, + _ => panic!("wrong predicate kind"), + }; + + assert_eq!(predicate.bounds.len(), 2, "{:#?}", predicate.bounds); + + let first_bound = &predicate.bounds[0]; + assert_eq!(quote!(#first_bound).to_string(), "FnOnce ( ) -> i32"); + + let second_bound = &predicate.bounds[1]; + assert_eq!(quote!(#second_bound).to_string(), "Send"); +} + +#[test] +fn test_where_clause_at_end_of_input() { + let input = quote! { + where + }; + + snapshot!(input as WhereClause, @"WhereClause"); + + assert_eq!(input.predicates.len(), 0); +} |