compiler/rustc_error_codes/src/error_codes/E0390.md

   1 A method was implemented on a primitive type.
   2
   3 Erroneous code example:
   4
   5 ```compile_fail,E0390
   6 struct Foo {
   7     x: i32
   8 }
   9
  10 impl *mut Foo {}
  11 // error: only a single inherent implementation marked with
  12 //        `#[lang = "mut_ptr"]` is allowed for the `*mut T` primitive
  13 ```
  14
  15 This isn't allowed, but using a trait to implement a method is a good solution.
  16 Example:
  17
  18 ```
  19 struct Foo {
  20     x: i32
  21 }
  22
  23 trait Bar {
  24     fn bar();
  25 }
  26
  27 impl Bar for *mut Foo {
  28     fn bar() {} // ok!
  29 }
  30 ```