feat(linter): typescript-eslint no-useless-empty-export

crates/oxc_linter/src/rules.rs

@@ -135,6 +135,7 @@ mod typescript {
     pub mod no_this_alias;
     pub mod no_unnecessary_type_constraint;
     pub mod no_unsafe_declaration_merging;
+    pub mod no_useless_empty_export;
     pub mod no_var_requires;
     pub mod prefer_as_const;
     pub mod prefer_enum_initializers;
@@ -517,6 +518,7 @@ oxc_macros::declare_all_lint_rules! {
     typescript::no_this_alias,
     typescript::no_unnecessary_type_constraint,
     typescript::no_unsafe_declaration_merging,
+    typescript::no_useless_empty_export,
     typescript::no_var_requires,
     typescript::prefer_as_const,
     typescript::prefer_for_of,

crates/oxc_linter/src/rules/typescript/no_useless_empty_export.rs

@@ -0,0 +1,129 @@
+use oxc_ast::AstKind;
+use oxc_diagnostics::OxcDiagnostic;
+use oxc_macros::declare_oxc_lint;
+use oxc_span::Span;
+
+use crate::{context::LintContext, rule::Rule, AstNode};
+
+fn no_useless_empty_export_diagnostic(span0: Span) -> OxcDiagnostic {
+    OxcDiagnostic::warn(
+        "typescript-eslint(no-useless-empty-export): Disallow empty exports that don't change anything in a module file",
+    )
+    .with_help("Empty export does nothing and can be removed.")
+    .with_labels([span0.into()])
+}
+
+#[derive(Debug, Default, Clone)]
+pub struct NoUselessEmptyExport;
+
+declare_oxc_lint!(
+    /// ### What it does
+    ///
+    /// Disallow empty exports that don't change anything in a module file.
+    ///
+    /// ### Example
+    ///
+    /// ### Bad
+    /// ```javascript
+    /// export const value = 'Hello, world!';
+    /// export {};
+    /// ```
+    ///
+    /// ### Good
+    /// ```javascript
+    /// export const value = 'Hello, world!';
+    /// ```
+    ///
+    NoUselessEmptyExport,
+    correctness
+);
+
+impl Rule for NoUselessEmptyExport {
+    fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
+        let AstKind::ExportNamedDeclaration(decl) = node.kind() else { return };
+        if decl.declaration.is_some() || !decl.specifiers.is_empty() {
+            return;
+        }
+        let module_record = ctx.semantic().module_record();
+        if module_record.exported_bindings.is_empty()
+            && module_record.local_export_entries.is_empty()
+            && module_record.indirect_export_entries.is_empty()
+            && module_record.star_export_entries.is_empty()
+            && module_record.export_default.is_none()
+        {
+            return;
+        }
+        ctx.diagnostic_with_fix(no_useless_empty_export_diagnostic(decl.span), |fixer| {
+            fixer.delete(&decl.span)
+        });
+    }
+}
+
+#[test]
+fn test() {
+    use crate::tester::Tester;
+
+    let pass = vec![
+        "declare module '_'",
+        "import {} from '_';",
+        "import * as _ from '_';",
+        "export = {};",
+        "export = 3;",
+        "export const _ = {};",
+        "
+            const _ = {};
+            export default _;
+        ",
+        "
+            export * from '_';
+            export = {};
+        ",
+        "export {};",
+    ];
+
+    let fail = vec![
+        "
+            export const _ = {};
+            export {};
+        ",
+        "
+            export * from '_';
+            export {};
+        ",
+        "
+            export {};
+            export * from '_';
+        ",
+        "
+            const _ = {};
+            export default _;
+            export {};
+        ",
+        "
+            export {};
+            const _ = {};
+            export default _;
+        ",
+        "
+            const _ = {};
+            export { _ };
+            export {};
+        ",
+        // "
+        // import _ = require('_');
+        // export {};
+        // ",
+    ];
+
+    let fix = vec![
+        ("export const _ = {};export {};", "export const _ = {};"),
+        ("export * from '_';export {};", "export * from '_';"),
+        ("export {};export * from '_';", "export * from '_';"),
+        ("const _ = {};export default _;export {};", "const _ = {};export default _;"),
+        ("export {};const _ = {};export default _;", "const _ = {};export default _;"),
+        ("const _ = {};export { _ };export {};", "const _ = {};export { _ };"),
+        // ("import _ = require('_');export {};", "import _ = require('_');"),
+    ];
+
+    Tester::new(NoUselessEmptyExport::NAME, pass, fail).expect_fix(fix).test_and_snapshot();
+}

crates/oxc_linter/src/snapshots/no_useless_empty_export.snap

@@ -0,0 +1,57 @@
+---
+source: crates/oxc_linter/src/tester.rs
+expression: no_useless_empty_export
+---
+  ⚠ typescript-eslint(no-useless-empty-export): Disallow empty exports that don't change anything in a module file
+   ╭─[no_useless_empty_export.tsx:3:13]
+ 2 │             export const _ = {};
+ 3 │             export {};
+   ·             ──────────
+ 4 │         
+   ╰────
+  help: Empty export does nothing and can be removed.
+
+  ⚠ typescript-eslint(no-useless-empty-export): Disallow empty exports that don't change anything in a module file
+   ╭─[no_useless_empty_export.tsx:3:13]
+ 2 │             export * from '_';
+ 3 │             export {};
+   ·             ──────────
+ 4 │         
+   ╰────
+  help: Empty export does nothing and can be removed.
+
+  ⚠ typescript-eslint(no-useless-empty-export): Disallow empty exports that don't change anything in a module file
+   ╭─[no_useless_empty_export.tsx:2:13]
+ 1 │ 
+ 2 │             export {};
+   ·             ──────────
+ 3 │             export * from '_';
+   ╰────
+  help: Empty export does nothing and can be removed.
+
+  ⚠ typescript-eslint(no-useless-empty-export): Disallow empty exports that don't change anything in a module file
+   ╭─[no_useless_empty_export.tsx:4:13]
+ 3 │             export default _;
+ 4 │             export {};
+   ·             ──────────
+ 5 │         
+   ╰────
+  help: Empty export does nothing and can be removed.
+
+  ⚠ typescript-eslint(no-useless-empty-export): Disallow empty exports that don't change anything in a module file
+   ╭─[no_useless_empty_export.tsx:2:13]
+ 1 │ 
+ 2 │             export {};
+   ·             ──────────
+ 3 │             const _ = {};
+   ╰────
+  help: Empty export does nothing and can be removed.
+
+  ⚠ typescript-eslint(no-useless-empty-export): Disallow empty exports that don't change anything in a module file
+   ╭─[no_useless_empty_export.tsx:4:13]
+ 3 │             export { _ };
+ 4 │             export {};
+   ·             ──────────
+ 5 │         
+   ╰────
+  help: Empty export does nothing and can be removed.