src/librustc_error_codes/error_codes/E0091.md

   1 An unnecessary type or const parameter was given in a type alias.
   2
   3 Erroneous code example:
   4
   5 ```compile_fail,E0091
   6 type Foo<T> = u32; // error: type parameter `T` is unused
   7 // or:
   8 type Foo<A,B> = Box<A>; // error: type parameter `B` is unused
   9 ```
  10
  11 Please check you didn't write too many parameters. Example:
  12
  13 ```
  14 type Foo = u32; // ok!
  15 type Foo2<A> = Box<A>; // ok!
  16 ```