error[E0107]: this enum takes 2 generic arguments but 1 generic argument was supplied
  --> $DIR/issue-75883.rs:6:21
   |
LL |     pub fn run() -> Result<_> {
   |                     ^^^^^^ - supplied 1 generic argument
   |                     |
   |                     expected 2 generic arguments
   |
help: add missing generic argument
   |
LL |     pub fn run() -> Result<_, E> {
   |                             +++

error[E0107]: this enum takes 2 generic arguments but 1 generic argument was supplied
  --> $DIR/issue-75883.rs:15:35
   |
LL |     pub fn interact(&mut self) -> Result<_> {
   |                                   ^^^^^^ - supplied 1 generic argument
   |                                   |
   |                                   expected 2 generic arguments
   |
help: add missing generic argument
   |
LL |     pub fn interact(&mut self) -> Result<_, E> {
   |                                           +++

error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
  --> $DIR/issue-75883.rs:15:42
   |
LL |     pub fn interact(&mut self) -> Result<_> {
   |                                          ^ not allowed in type signatures

error[E0121]: the placeholder `_` is not allowed within types on item signatures for return types
  --> $DIR/issue-75883.rs:6:28
   |
LL |     pub fn run() -> Result<_> {
   |                            ^ not allowed in type signatures

error: aborting due to 4 previous errors

Some errors have detailed explanations: E0107, E0121.
For more information about an error, try `rustc --explain E0107`.