compiler/rustc_error_codes/src/error_codes/E0424.md

   1 The `self` keyword was used inside of an associated function without a "`self`
   2 receiver" parameter.
   3
   4 Erroneous code example:
   5
   6 ```compile_fail,E0424
   7 struct Foo;
   8
   9 impl Foo {
  10     // `bar` is a method, because it has a receiver parameter.
  11     fn bar(&self) {}
  12
  13     // `foo` is not a method, because it has no receiver parameter.
  14     fn foo() {
  15         self.bar(); // error: `self` value is a keyword only available in
  16                     //        methods with a `self` parameter
  17     }
  18 }
  19 ```
  20
  21 The `self` keyword can only be used inside methods, which are associated
  22 functions (functions defined inside of a `trait` or `impl` block) that have a
  23 `self` receiver as its first parameter, like `self`, `&self`, `&mut self` or
  24 `self: &mut Pin<Self>` (this last one is an example of an ["arbitrary `self`
  25 type"](https://github.com/rust-lang/rust/issues/44874)).
  26
  27 Check if the associated function's parameter list should have contained a `self`
  28 receiver for it to be a method, and add it if so. Example:
  29
  30 ```
  31 struct Foo;
  32
  33 impl Foo {
  34     fn bar(&self) {}
  35
  36     fn foo(self) { // `foo` is now a method.
  37         self.bar(); // ok!
  38     }
  39 }
  40 ```