error: expected identifier, found keyword `let`
  --> $DIR/bad-let-as-field.rs:2:5
   |
LL | struct Foo {
   |        --- while parsing this struct
LL |     let: i32,
   |     ^^^ expected identifier, found keyword
   |
help: escape `let` to use it as an identifier
   |
LL |     r#let: i32,
   |     ++

error: aborting due to previous error