Preparation for #7073. Avoid using `AstBuilder::*_from_*` methods to construct enums, use explicit construction instead.
Before:
```rs
let ident = self.ast.binding_pattern_kind_from_binding_identifier(ident);
```
After:
```rs
let ident = BindingPatternKind::BindingIdentifier(ident);
```
Often this produces shorter code, as well as (in my opinion) being easier to read.
Pure refactor. Introduce `ParserImpl::alloc` method. Shorten `self.ast.alloc(...)` to `self.alloc(...)`.
Also reduce `alloc` calls by using `AstBuilder` methods which already allocate where possible.
Similar to #7055.
In transformer, use `AstBuilder::identifier_reference_with_reference_id` function, instead of creating an `IdentifierReference` and then setting the `reference_id` on it afterwards.
In transformer, use `AstBuilder::function_with_scope_id` and `AstBuilder::arrow_function_expression_with_scope_id` function where possible, rather than creating a function and then setting the `scope_id` on it afterwards.
Add ability for `VarDeclarations` to insert `let` declarations as well as `var` declarations. This is required for class properties transform.
Implementation note: `var` and `let` declarators are stored in 2 separate `ArenaVec`s. This allows using those `ArenaVec<Declarator<'a>>`s directly in the AST, rather storing all `Declarator`s in a single `Vec` and having to loop through it when inserting the `var` / `let` statements to split it into 2 `ArenaVec`s of `var` / `let` declarators. I'm not completely sure this is better than using a single `Vec` for both, but I think *probably* it is.
- closes https://github.com/oxc-project/oxc/issues/6988
we now return an error exit code when there are unmatched rules. previously, we would print an error to stderr and continue running. however, this masked errors in some tests that actually had unmatched rules in them. these test cases now trigger a panic (in tests only, not at runtime), and help ensure that we are reporting an error message to the user for unknown rules, which we did not have any tests cases for before.
- fixes https://github.com/oxc-project/oxc/issues/7025
this also fixes https://github.com/oxc-project/oxc/issues/7025, where we were reporting rules as unmatched simply because they had been disabled prior to being configured. similar to https://github.com/oxc-project/oxc/issues/7009.
Passed 15/19 tests. The remaining 4 failed tests related to `this` expression, the problem same as I mentioned in #6658. I will fix them in follow-up PRs.
This is a work towards https://github.com/oxc-project/oxc/issues/6982
Next PR will try and make sense of env options vs babel options vs targets and bugfixes, I'm super confused right now.
