Remove all direct uses of unwrap_or_return! in html5ever

[simonwuelker]

In modern rust this macro can almost always easily be replaced by let-else expressions.

Some uses inside other macros remain, those are not as easy to remove.

[simonwuelker]

CI needs #596 first

[mrobinson]

Excellent!

[mrobinson]

Can this just call Option::clone()?

Suggested change

	let Some(body) = self.body_elem().map(|b| b.clone()) else {
	let Some(body) = self.body_elem().clone() else {

[simonwuelker]

Surprisingly not!

error[E0599]: the method `clone` exists for enum `Option<Ref<'_, Handle>>`, but its trait bounds were not satisfied
    --> html5ever/src/tree_builder/rules.rs:332:55
     |
332  |                     let Some(body) = self.body_elem().clone() else {
     |                                                       ^^^^^ method cannot be called on `Option<Ref<'_, Handle>>` due to unsatisfied trait bounds
     |
    ::: /home/alaska/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/cell.rs:1463:1
     |
1463 | pub struct Ref<'b, T: ?Sized + 'b> {
     | ---------------------------------- doesn't satisfy `Ref<'_, Handle>: Clone`
     |
    ::: /home/alaska/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/option.rs:571:1
     |
571  | pub enum Option<T> {
     | ------------------ doesn't satisfy `Option<Ref<'_, Handle>>: Clone`
     |
     = note: the following trait bounds were not satisfied:
             `Ref<'_, Handle>: Clone`
             which is required by `Option<Ref<'_, Handle>>: Clone`
note: the method `clone` exists on the type `Ref<'_, Handle>`
    --> /home/alaska/.rustup/toolchains/stable-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/clone.rs:165:5
     |
165  |     fn clone(&self) -> Self;
     |     ^^^^^^^^^^^^^^^^^^^^^^^^
help: consider using `Option::expect` to unwrap the `Ref<'_, Handle>` value, panicking if the value is an `Option::None`
     |
332  |                     let Some(body) = self.body_elem().expect("REASON").clone() else {
     |                                                      +++++++++++++++++

For more information about this error, try `rustc --explain E0599`.
error: could not compile `html5ever` (lib) due to 1 previous error
warning: build failed, waiting for other jobs to finish...
error: could not compile `html5ever` (lib test) due to 1 previous error

To be honest, I have no idea what that error is complaining about.

[mrobinson]

Ah yeah, sometime when there is a Ref inside it needs to be dereferenced in order to access the real clone. Option::as_deref or Option::as_ref might work here, but otherwise the closure is fine.