error: this generic shadows the built-in type `u32`
  --> $DIR/builtin-type-shadow.rs:4:8
   |
LL | 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:5:5
   |
LL | fn foo<u32>(a: u32) -> u32 {
   |        ---             --- expected `u32` because of return type
   |        |
   |        this type parameter
LL |     42
   |     ^^ expected type parameter `u32`, found integer
   |
   = note: expected type parameter `u32`
                        found type `{integer}`

error: aborting due to 2 previous errors

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