Incorrect macro expansion with doubly nested macros

[jonas-schievink]

macro_rules! outer {
    ($block:block) => {
        {
            macro_rules! with_dollar_sign {
                ($a:tt => $b:tt) => {
                    macro_rules! __with_dollar_sign { $a => $b }
                    __with_dollar_sign!($);
                }
            }

            with_dollar_sign! {
                ($d:tt) => {
                    macro_rules! inner {
                        ($blk:block) => {
                            $blk
                        };
                    }
                }
            }
            $block
        }
    };
}

fn main() {
    outer!({
        let s = String::new();
        s.len();
        inner!({
            s.len();
        });
    });
}

Hover does not work within the inner! invocation here.

According to "Expand macro recursively" we expand inner! just fine, but fail to expand __with_dollar_sign! to the definition of inner!, which makes no sense:

{
  macro_rules!with_dollar_sign {
    ($a:tt = > $b:tt) = >{
      macro_rules!__with_dollar_sign {
        $a = > $b
      }__with_dollar_sign!($);
      
    }
  }macro_rules!__with_dollar_sign {
    ($d:tt) = >{
      macro_rules!inner {
        ($blk:block) = >{
          $blk
        };
        
      }
    }
  }__with_dollar_sign!($);
  {
    let s = String::new();
    s.len();
    {
      s.len();
      
    };
    
  }
}

It is possible that that part is due to a bug in the implementation of "Expand macro recursively".