feat(linter): add typescript-eslint/prefer-keyword-namespce (#4438)

crates/oxc_linter/src/rules.rs

@@ -158,6 +158,7 @@ mod typescript {
     pub mod prefer_for_of;
     pub mod prefer_function_type;
     pub mod prefer_literal_enum_member;
+    pub mod prefer_namespace_keyword;
     pub mod prefer_ts_expect_error;
     pub mod triple_slash_reference;
 }
@@ -569,6 +570,7 @@ oxc_macros::declare_all_lint_rules! {
     typescript::prefer_as_const,
     typescript::prefer_for_of,
     typescript::prefer_function_type,
+    typescript::prefer_namespace_keyword,
     typescript::prefer_ts_expect_error,
     typescript::triple_slash_reference,
     typescript::prefer_literal_enum_member,

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

@@ -0,0 +1,106 @@
+use oxc_ast::{
+    ast::{TSModuleDeclarationKind, TSModuleDeclarationName},
+    AstKind,
+};
+use oxc_diagnostics::OxcDiagnostic;
+use oxc_macros::declare_oxc_lint;
+use oxc_span::Span;
+
+use crate::{context::LintContext, rule::Rule, AstNode};
+
+fn prefer_namespace_keyword_diagnostic(span: Span) -> OxcDiagnostic {
+    OxcDiagnostic::warn("Use 'namespace' instead of 'module' to declare custom TypeScript modules.")
+        .with_label(span)
+}
+
+#[derive(Debug, Default, Clone)]
+pub struct PreferNamespaceKeyword;
+
+declare_oxc_lint!(
+    /// ### What it does
+    /// This rule reports when the module keyword is used instead of namespace.
+    /// This rule does not report on the use of TypeScript module declarations to describe external APIs (declare module 'foo' {}).
+    ///
+    /// ### Why is this bad?
+    /// Namespaces are an outdated way to organize TypeScript code. ES2015 module syntax is now preferred (import/export).
+    /// For projects still using custom modules / namespaces, it's preferred to refer to them as namespaces.
+    ///
+    /// ### Example
+    /// ```typescript
+    /// module Example {}
+    /// ```
+    PreferNamespaceKeyword,
+    style
+);
+
+impl Rule for PreferNamespaceKeyword {
+    fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
+        let AstKind::TSModuleDeclaration(module) = node.kind() else { return };
+        if module.id.is_string_literal()
+            || !matches!(module.id, TSModuleDeclarationName::Identifier(_))
+            || module.kind != TSModuleDeclarationKind::Module
+        {
+            return;
+        }
+
+        ctx.diagnostic_with_fix(prefer_namespace_keyword_diagnostic(module.span), |fixer| {
+            let span_size = u32::try_from("module".len()).unwrap_or(6);
+            let span_start = if module.declare {
+                module.span.start + u32::try_from("declare ".len()).unwrap_or(8)
+            } else {
+                module.span.start
+            };
+            fixer.replace(Span::sized(span_start, span_size), "namespace")
+        });
+    }
+
+    fn should_run(&self, ctx: &LintContext) -> bool {
+        ctx.source_type().is_typescript()
+    }
+}
+
+#[test]
+fn test() {
+    use crate::tester::Tester;
+
+    let pass = vec![
+        "declare module 'foo';",
+        "declare module 'foo' {}",
+        "namespace foo {}",
+        "declare namespace foo {}",
+        "declare global {}",
+    ];
+
+    let fail = vec![
+        "module foo {}",
+        "declare module foo {}",
+        "
+			declare module foo {
+			  declare module bar {}
+			}
+			      ",
+        "declare global {
+            module foo {}
+        }
+        ",
+    ];
+
+    let fix = vec![
+        ("module foo {}", "namespace foo {}", None),
+        ("declare module foo {}", "declare namespace foo {}", None),
+        (
+            "
+			declare module foo {
+			  declare module bar {}
+			}
+			      ",
+            "
+			declare namespace foo {
+			  declare namespace bar {}
+			}
+			      ",
+            None,
+        ),
+    ];
+    Tester::new(PreferNamespaceKeyword::NAME, pass, fail).expect_fix(fix).test_and_snapshot();
+}

crates/oxc_linter/src/snapshots/prefer_namespace_keyword.snap

@@ -0,0 +1,44 @@
+---
+source: crates/oxc_linter/src/tester.rs
+---
+  ⚠ typescript-eslint(prefer-namespace-keyword): Use 'namespace' instead of 'module' to declare custom TypeScript modules.
+   ╭─[prefer_namespace_keyword.tsx:1:1]
+ 1 │ module foo {}
+   · ─────────────
+   ╰────
+  help: Replace `module` with `namespace`.
+
+  ⚠ typescript-eslint(prefer-namespace-keyword): Use 'namespace' instead of 'module' to declare custom TypeScript modules.
+   ╭─[prefer_namespace_keyword.tsx:1:1]
+ 1 │ declare module foo {}
+   · ─────────────────────
+   ╰────
+  help: Replace `module` with `namespace`.
+
+  ⚠ typescript-eslint(prefer-namespace-keyword): Use 'namespace' instead of 'module' to declare custom TypeScript modules.
+   ╭─[prefer_namespace_keyword.tsx:2:4]
+ 1 │     
+ 2 │ ╭─▶             declare module foo {
+ 3 │ │                 declare module bar {}
+ 4 │ ╰─▶             }
+ 5 │                       
+   ╰────
+  help: Replace `module` with `namespace`.
+
+  ⚠ typescript-eslint(prefer-namespace-keyword): Use 'namespace' instead of 'module' to declare custom TypeScript modules.
+   ╭─[prefer_namespace_keyword.tsx:3:6]
+ 2 │             declare module foo {
+ 3 │               declare module bar {}
+   ·               ─────────────────────
+ 4 │             }
+   ╰────
+  help: Replace `module` with `namespace`.
+
+  ⚠ typescript-eslint(prefer-namespace-keyword): Use 'namespace' instead of 'module' to declare custom TypeScript modules.
+   ╭─[prefer_namespace_keyword.tsx:2:13]
+ 1 │ declare global {
+ 2 │             module foo {}
+   ·             ─────────────
+ 3 │         }
+   ╰────
+  help: Replace `module` with `namespace`.