warning: not reporting region error due to nll
  --> $DIR/issue-15034.rs:27:9
   |
LL |         Parser { lexer: lexer }
   |         ^^^^^^

error[E0621]: explicit lifetime required in the type of `lexer`
  --> $DIR/issue-15034.rs:27:25
   |
LL |     pub fn new(lexer: &'a mut Lexer) -> Parser<'a> {
   |                ----- consider changing the type of `lexer` to `&'a mut Lexer<'a>`
LL |         Parser { lexer: lexer }
   |                         ^^^^^ lifetime `'a` required

error: aborting due to previous error

For more information about this error, try `rustc --explain E0621`.