Reverse `if` arms in 2 very commonly-called methods in `Source` so that "not at EOF" is the first branch. This will encourage compiler to treat EOF as the cold branch (which it should be, as we're almost never at EOF).
`Lexer::read_left_angle` was a series of disparate `next_ascii_byte_eq` and `peek_byte` calls. Convert it to a single match on `peek_byte`. This I think will remove a couple of bounds checks.
Optimize `Lexer::hex_digit`.
Rather than checking for `A-F` and `a-f` separately, can check for them both in one go. `b'A' | 32 == b'a'` (and same for all other alphabetic letters) so matching against `b | 32` allows checking for all matching letters, lower or upper case, in one operation.
> Re-creation of #4427 due to rebasing issues. Original attempt: #642
-----
Third time's the charm?
Each time I attempt this rule, I find a bunch of bugs in `Semantic`, and I expect this attempt to be no different. Expect sidecar issues+PRs stemming from this PR here.
## Not Supported
These are cases supported in the original eslint rule, but that I'm intentionally deciding not to support
- export comments in scripts
```js
/* exported a */ var a;
```
- global comments
```js
/* global a */ var a;
```
## Behavior Changes
These are intentional deviations from the original rule's behavior:
- logical re-assignments are not considered usages
```js
// passes in eslint/no-unused-vars, fails in this implementation
let a = 0; a ||= 1;
let b = 0; b &&= 2;
let c = undefined; c ??= []
```
## Known Limitations
- Lint rules do not have babel or tsconfig information, meaning we can't determine if `React` imports are being used or not. The relevant tsconfig settings here are `jsx`, `jsxPragma`, and `jsxFragmentName`. To accommodate this, all imports to symbols named `React` or `h` are ignored in JSX files.
- References to symbols used in JSDoc `{@link}` tags are not created, so symbols that are only used in doc comments will be reported as unused. See: #4443
- `.vue` files are skipped completely, since variables can be used in templates in ways we cannot detect
> note: `.d.ts` files are skipped as well.
## Todo
- [x] Skip unused TS enum members on used enums
- [x] Skip unused parameters followed by used variables in object/array spreads
- [x] Re-assignments to array/object spreads do not respect `destructuredArrayIgnorePattern` (related to: https://github.com/oxc-project/oxc/issues/4435)
- [x] #4493
- [x] References inside a nested scope are not considered usages (#4447)
- [x] Port over typescript-eslint test cases _(wip, they've been copied and I'm slowly enabling them)_
- [x] Handle constructor properties
```ts
class Foo {
constructor(public a) {} // `a` should be allowed
}
```
- [x] Read references in sequence expressions (that are not in the last position) should not count as a usage
```js
let a = 0; let b = (a++, 0); console.log(b)
```
> Honestly, is anyone even writing code like this?
- [x] function overload signatures should not be reported
- [x] Named functions returned from other functions get incorrectly reported as unused (found by @camc314)
```js
function foo() {
return function bar() { }
}
Foo()()
```
- [x] false positive for TS modules within ambient modules
```ts
declare global {
// incorrectly marked as unused
namespace jest { }
}
```
## Blockers
- https://github.com/oxc-project/oxc/issues/4436
- https://github.com/oxc-project/oxc/issues/4437
- #4446
- #4447
- #4494
- #4495
## Non-Blocking Issues
- #4443
- #4475 (prevents checks on exported symbols from namespaces)
Add a `FIX` constant to `RuleMeta` that describes what kinds of auto
fixes a
rule can perform (if any). This PR also updates `declare_oxc_lint` to
accept a
fix capabilities field. Follow-up PRs in this stack will update existing
rules
and update other parts of the codebase to use this new field.
The end goal of this stack is to
1. automate creation of #4179 in a similar way we auto-update rule
progress,
2. use it in rule documentation pages when we eventually add lint rules
to the website
Rule Detail:
[link](https://eslint.org/docs/latest/rules/prefer-numeric-literals)
---
This lacks the fix, which I intend to work on as a follow up or if
preferred I can leave the PR open an hack on it this week.
One interesting note is that `eslint(radix)` does not handle:
```
"function *f(){ yield(Number).parseInt('11', 2) }", // { "ecmaVersion": 6 },
```
Maybe it is an idea to introduce a helper `is_parseint_stmt` which
returns the `call_expr`? As the code is almost identical to the `radix`
rule.
---------
Co-authored-by: wenzhe <mysteryven@gmail.com>
Add `Lexer::consume_2_chars` to replace `lexer.consume_char(); lexer.consume_char();`. Mostly this is just neater code, but *may* also help compiler to elide bounds checks when it's preceded by `lexer.peek_2_bytes()`.
Iterating over `str.as_bytes()` produces `&u8`s. Dereference to `u8` in `for` statement. Should make no difference to generated assembly, purely making this change for neater code style.
Follow-on after #4304. Avoid using `saturating_sub` when plain `-` will do. `-` is cheaper - it's a single assembly instruction, whereas `saturating_sub` is usually 3 instructions.
https://godbolt.org/z/fo8Tcx6bK
Refactors a lot of case-insensitive comparisons from
```rust
a.to_lowercase() == b.to_lowercase()
```
with
```rust
a.eq_ignore_ascii_case(b)
```
These mostly happened when checking JSX props, so I'm expecting the most benefit from JSX-related rules.
Fix 2 mistakes in the `#[cfg]` for custom allocators in `oxlint` CLI.
1. `#![cfg(not(miri))]` at top of file was disabling the entire module if running miri, rather than just disabling custom allocator.
2. If both `target_os = "windows"` and `not(target_env = "msvc")`, it would try to register both mimalloc and jemalloc as global allocator.
I am actually not sure if it's possible to compile for Windows without using MSVC, but it seems like a good idea not to assume.
Closes#4537.
`oxc_traverse`'s tests to ensure code which would be undefined behavior will not compile were using `trybuild`. This is a thorough way to run these tests, but requires running a lengthy compilation each time tests run.
Implement these tests as `compile_fail` doc tests instead. This is not quite as thorough - now only testing that they don't compile, rather than also *why* they don't compile - but acceptable given the outsized cost of doing it "properly".
Refactor `AstNodeParentIter`, which is used to iterate down node ancestry chain. Fetch `AstNode` objects lazily, only when they're required by a `next()` call. If caller doesn't iterate all the way down the chain, likely this will result in 1 less array lookup.
These 2 `#[inline(always)]` were introduced by accident by me just playing around in #4298. One should be kept, but the other one we should leave to compiler to decide.
Also optimize the memory allocation in string escape. The default size in `serde_json` is 1024 for String type, we pre allocate `string.len() * 2 + 2` for every string to reduce re-allocate in escaping.
I've tried to hand write SIMD implementation, but it's too complex, so I uses the `v_jsonescape` here. But it doesn't support `aarch64` and `wasm32` simd implementation, we need to contribute to it!
Make 2 changes to sourcemap benchmark:
1. Move counting line breaks in output text to outside of the measured loop. This operation is reasonably expensive, and isn't part of what we're trying to measure.
2. It looks like benchmark is trying to measure concatenating 2 source maps, but `for i in 0..1` was actually only concatenating 1.
After https://github.com/oxc-project/oxc/pull/4511. We can determine if a binding is a type binding just by the `ReferenceFlags`.
We can make it even better with `ident.reference_flag` once #4512 is sorted out
```ts
type T = 0;
export { T }
^ ReferenceFlags::Type | ReferenceFlags::Read
```
The export `T` only referenced type binding. We should remove `ReferenceFlags::Read` for it.
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|---|---|---|---|
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---
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[Compare Source](https://togithub.com/CodSpeedHQ/action/compare/v2...v3)
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---
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---
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