error: expected one of `!`, `(`, `+`, `,`, `::`, `<`, or `>`, found `=`
--> $DIR/trait-path-expected-token.rs:5:33
|
LL | fn f1<'a>(arg : Box<dyn X<Y = B = &'a ()>>) {}
| ^ expected one of 7 possible tokens
error: aborting due to 1 previous error