error: missing angle brackets in associated item path
  --> $DIR/issue-89388.rs:5:24
   |
LL |     let _ = option.map([_]::to_vec);
   |                        ^^^
   |
help: types that don't start with an identifier need to be surrounded with angle brackets in qualified paths
   |
LL |     let _ = option.map(<[_]>::to_vec);
   |                        +   +

error: aborting due to previous error