diff options
| -rw-r--r-- | src/librustc_typeck/error_codes.rs | 30 |
1 files changed, 16 insertions, 14 deletions
diff --git a/src/librustc_typeck/error_codes.rs b/src/librustc_typeck/error_codes.rs index ae0f1789295..ebfa6acf23e 100644 --- a/src/librustc_typeck/error_codes.rs +++ b/src/librustc_typeck/error_codes.rs @@ -212,7 +212,7 @@ match string { E0033: r##" This error indicates that a pointer to a trait type cannot be implicitly dereferenced by a pattern. Every trait defines a type, but because the -size of trait implementors isn't fixed, this type has no compile-time size. +size of trait implementers isn't fixed, this type has no compile-time size. Therefore, all accesses to trait types must be through pointers. If you encounter this error you should try to avoid dereferencing the pointer. @@ -2430,23 +2430,23 @@ This error indicates that the `self` parameter in a method has an invalid "reciever type". Methods take a special first parameter, of which there are three variants: -`self`, `&self`, and `&mut self`. The type `Self` acts as an alias to the -type of the current trait implementor, or "receiver type". Besides the -already mentioned `Self`, `&Self` and `&mut Self` valid receiver types, the -following are also valid, if less common: `self: Box<Self>`, -`self: Rc<Self>`, `self: Arc<Self>`, and `self: Pin<P>` (where P is one of -the previous types except `Self`). +`self`, `&self`, and `&mut self`. These are syntactic sugar for +`self: Self`, `self: &Self`, and `self: &mut Self` respectively. The type +`Self` acts as an alias to the type of the current trait implementer, or +"receiver type". Besides the already mentioned `Self`, `&Self` and +`&mut Self` valid receiver types, the following are also valid: +`self: Box<Self>`, `self: Rc<Self>`, `self: Arc<Self>`, and `self: Pin<P>` +(where P is one of the previous types except `Self`). ``` # struct Foo; trait Trait { fn foo(&self); -// ^^^^^ this let's you refer to the type that implements this trait } + impl Trait for Foo { -// ^^^ this is the "receiver type" fn foo(&self) {} -// ^^^^^ this is of type `Foo` +// ^^^^^ this the receiver type `&Foo` } ``` @@ -2458,11 +2458,12 @@ The above is equivalent to: # fn foo(&self); # } impl Trait for Foo { - fn foo(&self: &Foo) {} + fn foo(self: &Foo) {} } ``` -When using an invalid reciver type, like in the following example, +E0307 will be emitted by the compiler when using an invalid reciver type, +like in the following example: ```compile_fail,E0307 # struct Foo; @@ -2471,12 +2472,13 @@ When using an invalid reciver type, like in the following example, # fn foo(&self); # } impl Trait for Struct { - fn foo(&self: &Bar) {} + fn foo(self: &Bar) {} } ``` The nightly feature [Arbintrary self types][AST] extends the accepted -receiver type to also include any type that can dereference to `Self`: +set of receiver types to also include any type that can dereference to +`Self`: ``` #![feature(arbitrary_self_types)] |