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feat(linter): no-unused-vars add setting for reportVarsOnlyUsedAsTypes (#11009)
closes #11006 adds an option called `reportVarsOnlyUsedAsType`, defaulting to false when enabled, it will report code such as ```ts const x = 123; export type X = typeof x; ```
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‎crates/oxc_linter/src/rules/eslint/no_unused_vars/options.rs‎

Lines changed: 35 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -205,6 +205,34 @@ pub struct NoUnusedVarsOptions {
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/// console.log(firstVar, secondVar);
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/// ```
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pub report_used_ignore_pattern: bool,
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/// The `reportVarsOnlyUsedAsTypes` option is a boolean (default: `false`).
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///
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/// If `true`, the rule will also report variables that are only used as types.
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///
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/// ## Examples
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///
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/// Examples of **incorrect** code for the `{ "reportVarsOnlyUsedAsTypes": true }` option:
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///
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/// ```javascript
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/// /* eslint no-unused-vars: ["error", { "reportVarsOnlyUsedAsTypes": true }] */
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///
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/// const myNumber: number = 4;
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/// export type MyNumber = typeof myNumber
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/// ```
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///
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/// Examples of **correct** code for the `{ "reportVarsOnlyUsedAsTypes": true }` option:
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///
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/// ```javascript
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/// export type MyNumber = number;
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/// ```
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///
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/// Note: even with `{ "reportVarsOnlyUsedAsTypes": false }`, cases where the value is
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/// only used a type within itself will still be reported:
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/// ```javascript
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/// function foo(): typeof foo {}
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/// ```
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pub report_vars_only_used_as_types: bool,
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}
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/// Represents an `Option<Regex>` with an additional `Default` variant,
@@ -314,6 +342,7 @@ impl Default for NoUnusedVarsOptions {
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destructured_array_ignore_pattern: IgnorePattern::None,
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ignore_class_with_static_init_block: false,
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report_used_ignore_pattern: false,
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report_vars_only_used_as_types: false,
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}
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}
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}
@@ -555,6 +584,11 @@ impl TryFrom<Value> for NoUnusedVarsOptions {
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.map_or(Some(false), Value::as_bool)
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.unwrap_or(false);
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let report_vars_only_used_as_types: bool = config
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.get("reportVarsOnlyUsedAsTypes")
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.map_or(Some(false), Value::as_bool)
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.unwrap_or(false);
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Ok(Self {
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vars,
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vars_ignore_pattern,
@@ -566,6 +600,7 @@ impl TryFrom<Value> for NoUnusedVarsOptions {
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destructured_array_ignore_pattern,
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ignore_class_with_static_init_block,
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report_used_ignore_pattern,
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report_vars_only_used_as_types,
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})
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}
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Value::Null => Ok(Self::default()),

‎crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs‎

Lines changed: 27 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1253,6 +1253,33 @@ fn test_loops() {
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Tester::new(NoUnusedVars::NAME, NoUnusedVars::PLUGIN, pass, fail).expect_fix(fix).test();
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}
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#[test]
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fn test_report_vars_only_used_as_types() {
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let pass = vec![
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("const foo = 123; export type Foo = typeof foo;", None),
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(
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"const foo = 123; export type Foo = typeof foo;",
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Some(json!([{ "reportVarsOnlyUsedAsTypes": false, "varsIgnorePattern": "^_" }])),
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),
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(
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"export const foo = 123; export type Foo = typeof foo;",
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Some(json!([{ "reportVarsOnlyUsedAsTypes": true, "varsIgnorePattern": "^_" }])),
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),
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];
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let fail = vec![
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(
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"const foo = 123; export type Foo = typeof foo;",
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Some(json!([{ "reportVarsOnlyUsedAsTypes": true, "varsIgnorePattern": "^_" }])),
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),
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("function foo(): typeof foo {}", None),
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];
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Tester::new(NoUnusedVars::NAME, NoUnusedVars::PLUGIN, pass, fail)
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.intentionally_allow_no_fix_tests()
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.test();
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}
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// #[test]
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// fn test_template() {
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// let pass = vec![];

‎crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/typescript_eslint.rs‎

Lines changed: 6 additions & 8 deletions
Original file line numberDiff line numberDiff line change
@@ -3,8 +3,6 @@ use serde_json::json;
33
use super::NoUnusedVars;
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use crate::{RuleMeta as _, tester::Tester};
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6-
// TODO: port these over. I (@DonIsaac) would love some help with this...
7-
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#[test]
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fn test() {
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let pass = vec![
@@ -1731,28 +1729,28 @@ fn test() {
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const foo: number = 1;
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export type Foo = typeof foo;
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",
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None,
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Some(json!([{ "reportVarsOnlyUsedAsTypes": true, "varsIgnorePattern": "^_" }])),
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),
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(
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"
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declare const foo: number;
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export type Foo = typeof foo;
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",
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None,
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Some(json!([{ "reportVarsOnlyUsedAsTypes": true, "varsIgnorePattern": "^_" }])),
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),
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(
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"
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const foo: number = 1;
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export type Foo = typeof foo | string;
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",
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None,
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Some(json!([{ "reportVarsOnlyUsedAsTypes": true, "varsIgnorePattern": "^_" }])),
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),
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(
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"
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const foo: number = 1;
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export type Foo = (typeof foo | string) & { __brand: 'foo' };
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",
1755-
None,
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Some(json!([{ "reportVarsOnlyUsedAsTypes": true, "varsIgnorePattern": "^_" }])),
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),
17571755
(
17581756
"
@@ -1763,7 +1761,7 @@ fn test() {
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};
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export type Bar = typeof foo.bar;
17651763
",
1766-
None,
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Some(json!([{ "reportVarsOnlyUsedAsTypes": true, "varsIgnorePattern": "^_" }])),
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),
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(
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"
@@ -1774,7 +1772,7 @@ fn test() {
17741772
};
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export type Bar = (typeof foo)['bar'];
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",
1777-
None,
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Some(json!([{ "reportVarsOnlyUsedAsTypes": true, "varsIgnorePattern": "^_" }])),
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),
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];
17801778

‎crates/oxc_linter/src/rules/eslint/no_unused_vars/usage.rs‎

Lines changed: 15 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -137,11 +137,25 @@ impl<'a> Symbol<'_, 'a> {
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continue;
138138
}
139139

140-
if !self.flags().intersects(SymbolFlags::TypeImport.union(SymbolFlags::Import))
140+
// ```ts
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// const foo = 123;
142+
// export type Foo = typeof foo
143+
// ```
144+
if options.report_vars_only_used_as_types
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&& !self.flags().intersects(SymbolFlags::TypeImport.union(SymbolFlags::Import))
141146
&& self.reference_contains_type_query(reference)
142147
{
143148
continue;
144149
}
150+
// ```
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// function foo(): foo { }
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// ```
153+
if self
154+
.get_ref_relevant_node(reference)
155+
.is_some_and(|node| self.declaration().span().contains_inclusive(node.span()))
156+
{
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continue;
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}
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return true;
147161
}

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