diff --git a/compiler/rustc_error_codes/src/error_codes.rs b/compiler/rustc_error_codes/src/error_codes.rs index 789a1fc35a6..b0be1bf7e72 100644 --- a/compiler/rustc_error_codes/src/error_codes.rs +++ b/compiler/rustc_error_codes/src/error_codes.rs @@ -455,6 +455,7 @@ E0770: include_str!("./error_codes/E0770.md"), E0771: include_str!("./error_codes/E0771.md"), E0773: include_str!("./error_codes/E0773.md"), +E0774: include_str!("./error_codes/E0774.md"), ; // E0006, // merged with E0005 // E0008, // cannot bind by-move into a pattern guard diff --git a/compiler/rustc_error_codes/src/error_codes/E0774.md b/compiler/rustc_error_codes/src/error_codes/E0774.md new file mode 100644 index 00000000000..79793ba9d7d --- /dev/null +++ b/compiler/rustc_error_codes/src/error_codes/E0774.md @@ -0,0 +1,24 @@ +`derive` was applied on something which is not a struct, a union or an enum. + +Erroneous code example: + +```compile_fail,E0774 +trait Foo { + #[derive(Clone)] // error! + type Bar; +} +``` + +As said above, the `derive` attribute is only allowed on structs, unions or +enums: + +``` +#[derive(Clone)] // ok! +struct Bar { + field: u32, +} +``` + +You can find more information about `derive` in the [Rust Book]. + +[Rust Book]: https://doc.rust-lang.org/book/appendix-03-derivable-traits.html diff --git a/compiler/rustc_expand/src/expand.rs b/compiler/rustc_expand/src/expand.rs index 105f81c6e0f..ca6f7324ca4 100644 --- a/compiler/rustc_expand/src/expand.rs +++ b/compiler/rustc_expand/src/expand.rs @@ -529,9 +529,12 @@ pub fn fully_expand_fragment(&mut self, input_fragment: AstFragment) -> AstFragm fn error_derive_forbidden_on_non_adt(&self, derives: &[Path], item: &Annotatable) { let attr = self.cx.sess.find_by_name(item.attrs(), sym::derive); let span = attr.map_or(item.span(), |attr| attr.span); - let mut err = self - .cx - .struct_span_err(span, "`derive` may only be applied to structs, enums and unions"); + let mut err = rustc_errors::struct_span_err!( + self.cx.sess, + span, + E0774, + "`derive` may only be applied to structs, enums and unions", + ); if let Some(ast::Attribute { style: ast::AttrStyle::Inner, .. }) = attr { let trait_list = derives.iter().map(|t| pprust::path_to_string(t)).collect::>(); let suggestion = format!("#[derive({})]", trait_list.join(", "));