error: This generic shadows the built-in type `u32`
  --> $DIR/builtin-type-shadow.rs:12:8
   |
12 | fn foo<u32>(a: u32) -> u32 {
   |        ^^^
   |
   = note: `-D clippy::builtin-type-shadow` implied by `-D warnings`

error[E0308]: mismatched types
  --> $DIR/builtin-type-shadow.rs:13:5
   |
12 | fn foo<u32>(a: u32) -> u32 {
   |                        --- expected `u32` because of return type
13 |     42
   |     ^^ expected type parameter, found integral variable
   |
   = note: expected type `u32`
              found type `{integer}`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0308`.