From dd142b1dc43f0e9a9b860003816b1a91b4e1a52d Mon Sep 17 00:00:00 2001 From: Guillaume Gomez Date: Sun, 1 Mar 2020 12:03:38 +0100 Subject: [PATCH] Clean up E0376 explanation --- src/librustc_error_codes/error_codes/E0376.md | 21 ++++++++++--------- 1 file changed, 11 insertions(+), 10 deletions(-) diff --git a/src/librustc_error_codes/error_codes/E0376.md b/src/librustc_error_codes/error_codes/E0376.md index b028aab45831f..50de15bd30f09 100644 --- a/src/librustc_error_codes/error_codes/E0376.md +++ b/src/librustc_error_codes/error_codes/E0376.md @@ -1,14 +1,6 @@ -The type you are trying to impl `CoerceUnsized` for is not a struct. -`CoerceUnsized` can only be implemented for a struct. Unsized types are -already able to be coerced without an implementation of `CoerceUnsized` -whereas a struct containing an unsized type needs to know the unsized type -field it's containing is able to be coerced. An [unsized type][1] -is any type that the compiler doesn't know the length or alignment of at -compile time. Any struct containing an unsized type is also unsized. - -[1]: https://doc.rust-lang.org/book/ch19-04-advanced-types.html#dynamically-sized-types-and-the-sized-trait +`CoerceUnsized` was implemented on something that isn't a struct. -Example of erroneous code: +Erroneous code example: ```compile_fail,E0376 #![feature(coerce_unsized)] @@ -22,6 +14,15 @@ struct Foo { impl CoerceUnsized for Foo {} ``` +`CoerceUnsized` can only be implemented for a struct. Unsized types are +already able to be coerced without an implementation of `CoerceUnsized` +whereas a struct containing an unsized type needs to know the unsized type +field it's containing is able to be coerced. An [unsized type][1] +is any type that the compiler doesn't know the length or alignment of at +compile time. Any struct containing an unsized type is also unsized. + +[1]: https://doc.rust-lang.org/book/ch19-04-advanced-types.html#dynamically-sized-types-and-the-sized-trait + The `CoerceUnsized` trait takes a struct type. Make sure the type you are providing to `CoerceUnsized` is a struct with only the last field containing an unsized type.