error[E0283]: type annotations needed: cannot satisfy `T: FnMut(&'a ())` --> $DIR/issue-85735.rs:7:8 | LL | T: FnMut(&'a ()), | ^^^^^^^^^^^^^ | note: multiple `impl`s or `where` clauses satisfying `T: FnMut(&'a ())` found --> $DIR/issue-85735.rs:7:8 | LL | T: FnMut(&'a ()), | ^^^^^^^^^^^^^ LL | LL | T: FnMut(&'b ()), | ^^^^^^^^^^^^^ error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0283`.