Fix some Clippy warnings

[mcarton]

There are 5 warnings left:

• one needless_lifetimes which is a false positive (reported there: https://github.com/Manishearth/rust-clippy/issues/740#issuecomment-205826823);
• 3 type_complexity warnings that I did not fix because they seem legit;
• one wrong_self_convention which seems semi-legit too, although it’s a little surprising to have an is_empty function require a &mut self.

Here they are, FYI:

src/router/tree_router.rs:80:5: 110:6 warning: explicit lifetimes given in parameter types where they could be elided, #[warn(needless_lifetimes)] on by default
src/router/tree_router.rs: 80     fn merge_router<'a, I: Iterator<Item = &'a [u8]> + Clone>(&mut self, state: InsertState<'a, I>, router: TreeRouter<T>) {
src/router/tree_router.rs: 81         self.item.insert_router(state.clone(), router.item);
src/router/tree_router.rs: 82 
src/router/tree_router.rs: 83         for (key, router) in router.static_routes {
src/router/tree_router.rs: 84             let next = match self.static_routes.entry(key.clone()) {
src/router/tree_router.rs: 85                 Occupied(entry) => entry.into_mut(),
                              ...
src/router/tree_router.rs:80:5: 110:6 help: for further information visit https://github.com/Manishearth/rust-clippy/wiki#needless_lifetimes
src/router/mod.rs:357:21: 357:71 warning: very complex type used. Consider factoring parts into `type` definitions, #[warn(type_complexity)] on by default
src/router/mod.rs:357     type Segments = RouteIter<Split<'a, u8, &'static fn(&u8) -> bool>>;
                                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/router/mod.rs:357:21: 357:71 help: for further information visit https://github.com/Manishearth/rust-clippy/wiki#type_complexity
src/router/mod.rs:365:21: 365:71 warning: very complex type used. Consider factoring parts into `type` definitions, #[warn(type_complexity)] on by default
src/router/mod.rs:365     type Segments = RouteIter<Split<'a, u8, &'static fn(&u8) -> bool>>;
                                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/router/mod.rs:365:21: 365:71 help: for further information visit https://github.com/Manishearth/rust-clippy/wiki#type_complexity
src/router/mod.rs:393:21: 393:170 warning: very complex type used. Consider factoring parts into `type` definitions, #[warn(type_complexity)] on by default
src/router/mod.rs:393     type Segments = FlatMap<<&'a I as IntoIterator>::IntoIter, <<T as Deref>::Target as Route<'a>>::Segments, fn(&'a T) -> <<T as Deref>::Target as Route<'a>>::Segments>;
                                          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
src/router/mod.rs:393:21: 393:170 help: for further information visit https://github.com/Manishearth/rust-clippy/wiki#type_complexity
src/router/mod.rs:449:21: 449:34 warning: methods called `is_*` usually take self by reference or no self; consider choosing a less ambiguous name, #[warn(wrong_self_convention)] on by default
src/router/mod.rs:449     pub fn is_empty(&mut self) -> bool {
                                          ^~~~~~~~~~~~~
src/router/mod.rs:449:21: 449:34 help: for further information visit https://github.com/Manishearth/rust-clippy/wiki#wrong_self_convention

[Ogeon]

Very nice! It's just that one case with unwrap_or vs unwrap_or_else.

The complicated types could possibly move out of the trait implementations, but I would rather just find a better alternative to that pattern. They can stay for now. The is_empty case is caused by the peek function. I could, perhaps, rename it.

It's nice to see that the false positives are fewer this time :smile:

[Ogeon]

Never mind, it's all good (except for my brain, apparently). Thanks for running these checks.

@homu r+

[homu]

:pushpin: Commit e59e0d1 has been approved by Ogeon

[homu]

:zap: Test exempted - status