feat(linter): add the eslint/no_duplicate_imports rule

crates/oxc_linter/src/rules.rs

@@ -28,6 +28,7 @@ mod import {
 
 mod eslint {
     pub mod array_callback_return;
+    pub mod no_duplicate_imports;
     pub mod constructor_super;
     pub mod default_case;
     pub mod default_case_last;
@@ -519,6 +520,7 @@ oxc_macros::declare_all_lint_rules! {
     eslint::max_classes_per_file,
     eslint::max_lines,
     eslint::max_params,
+    eslint::no_duplicate_imports,
     eslint::no_alert,
     eslint::no_array_constructor,
     eslint::no_async_promise_executor,

crates/oxc_linter/src/rules/eslint/no_duplicate_imports.rs

@@ -0,0 +1,264 @@
+use std::collections::HashMap;
+
+use oxc_ast::{
+    ast::{ImportDeclaration, ImportDeclarationSpecifier},
+    AstKind,
+};
+use oxc_diagnostics::OxcDiagnostic;
+use oxc_macros::declare_oxc_lint;
+use oxc_span::Span;
+
+use crate::{context::LintContext, rule::Rule};
+
+fn no_duplicate_imports_diagnostic(module_name: &str, span: Span) -> OxcDiagnostic {
+    OxcDiagnostic::warn(format!("'{}' import is duplicated", module_name))
+        .with_help("Merge the duplicated import into a single import statement")
+        .with_label(span)
+}
+
+#[derive(Debug, Default, Clone)]
+pub struct NoDuplicateImports {}
+
+declare_oxc_lint!(
+    /// ### What it does
+    /// Disallow duplicate module imports
+    ///
+    /// ### Why is this bad?
+    /// Using a single import statement per module will make the code clearer because you can see everything being imported from that module on one line.
+    ///
+    /// ### Examples
+    ///
+    /// Examples of **incorrect** code for this rule:
+    /// ```js
+    /// import { merge } from 'module';
+    /// import something from 'another-module';
+    /// import { find } from 'module';
+    /// ```
+    ///
+    /// Examples of **correct** code for this rule:
+    /// ```js
+    /// import { merge, find } from 'module';
+    /// import something from 'another-module';
+    /// ```
+    NoDuplicateImports,
+    style,
+    pending);
+
+#[derive(Debug, Clone)]
+enum DeclarationType {
+    Import,
+}
+
+#[derive(Debug, Clone)]
+struct ModuleEntry {
+    declaration_type: DeclarationType,
+}
+
+impl Rule for NoDuplicateImports {
+    fn run_once(&self, ctx: &LintContext) {
+        let semantic = ctx.semantic();
+        let nodes = semantic.nodes();
+
+        let mut modules: HashMap<String, Vec<ModuleEntry>> = HashMap::new();
+
+        for node in nodes {
+            match node.kind() {
+                AstKind::ImportDeclaration(import_decl) => {
+                    handle_import(import_decl, &mut modules, ctx);
+                }
+                _ => {}
+            }
+        }
+    }
+}
+
+fn handle_import(
+    import_decl: &ImportDeclaration,
+    modules: &mut HashMap<String, Vec<ModuleEntry>>,
+    ctx: &LintContext,
+) {
+    let source = &import_decl.source;
+    let module_name = source.value.to_string();
+    if let Some(specifiers) = &import_decl.specifiers {
+        let has_namespace = specifiers.iter().any(|s| match s {
+            ImportDeclarationSpecifier::ImportDefaultSpecifier(_) => false,
+            ImportDeclarationSpecifier::ImportNamespaceSpecifier(_) => true,
+            _ => false,
+        });
+        if has_namespace {
+            return;
+        }
+    }
+    if let Some(existing_modules) = modules.get(&module_name) {
+        if existing_modules
+            .iter()
+            .any(|entry| matches!(entry.declaration_type, DeclarationType::Import))
+        {
+            ctx.diagnostic(no_duplicate_imports_diagnostic(&module_name, import_decl.span));
+            return;
+        }
+    }
+
+    let entry = ModuleEntry { declaration_type: DeclarationType::Import };
+    modules.entry(module_name.clone()).or_default().push(entry);
+}
+
+#[test]
+fn test() {
+    use crate::tester::Tester;
+
+    let pass = vec![
+        (
+            r#"import os from "os";
+    		import fs from "fs";"#,
+            None,
+        ),
+        (r#"import { merge } from "lodash-es";"#, None),
+        (r#"import _, { merge } from "lodash-es";"#, None),
+        (r#"import * as Foobar from "async";"#, None),
+        (r#"import "foo""#, None),
+        (
+            r#"import os from "os";
+    		export { something } from "os";"#,
+            None,
+        ),
+        (
+            r#"import * as bar from "os";
+    		import { baz } from "os";"#,
+            None,
+        ),
+        (
+            r#"import foo, * as bar from "os";
+    		import { baz } from "os";"#,
+            None,
+        ),
+        (
+            r#"import foo, { bar } from "os";
+    		import * as baz from "os";"#,
+            None,
+        ),
+        (
+            r#"import os from "os";
+    		export { hello } from "hello";"#,
+            Some(serde_json::json!([{ "includeExports": true }])),
+        ),
+        (
+            r#"import os from "os";
+    		export * from "hello";"#,
+            Some(serde_json::json!([{ "includeExports": true }])),
+        ),
+        (
+            r#"import os from "os";
+    		export { hello as hi } from "hello";"#,
+            Some(serde_json::json!([{ "includeExports": true }])),
+        ),
+        (
+            r#"import os from "os";
+    		export default function(){};"#,
+            Some(serde_json::json!([{ "includeExports": true }])),
+        ),
+        (
+            r#"import { merge } from "lodash-es";
+    		export { merge as lodashMerge }"#,
+            Some(serde_json::json!([{ "includeExports": true }])),
+        ),
+        (
+            r#"export { something } from "os";
+    		export * as os from "os";"#,
+            Some(serde_json::json!([{ "includeExports": true }])),
+        ),
+        (
+            r#"import { something } from "os";
+    		export * as os from "os";"#,
+            Some(serde_json::json!([{ "includeExports": true }])),
+        ),
+        (
+            r#"import * as os from "os";
+    		export { something } from "os";"#,
+            Some(serde_json::json!([{ "includeExports": true }])),
+        ),
+        (
+            r#"import os from "os";
+    		export * from "os";"#,
+            Some(serde_json::json!([{ "includeExports": true }])),
+        ),
+        (
+            r#"export { something } from "os";
+    		export * from "os";"#,
+            Some(serde_json::json!([{ "includeExports": true }])),
+        ),
+    ];
+
+    let fail = vec![
+        (
+            r#"import "fs";
+    		import "fs""#,
+            None,
+        ),
+        (
+            r#"import { merge } from "lodash-es";
+    		import { find } from "lodash-es";"#,
+            None,
+        ),
+        (
+            r#"import { merge } from "lodash-es";
+        import _ from "lodash-es";"#,
+            None,
+        ),
+        (
+            r#"import os from "os";
+        import { something } from "os";
+        import * as foobar from "os";"#,
+            None,
+        ),
+        (
+            r#"import * as modns from "lodash-es";
+        import { merge } from "lodash-es";
+        import { baz } from "lodash-es";"#,
+            None,
+        ),
+        // (
+        //     r#"export { os } from "os";
+        // export { something } from "os";"#,
+        //     Some(serde_json::json!([{ "includeExports": true }])),
+        // ),
+        // (
+        //     r#"import os from "os";
+        // export { os as foobar } from "os";
+        // export { something } from "os";"#,
+        //     Some(serde_json::json!([{ "includeExports": true }])),
+        // ),
+        //   (
+        //       r#"import os from "os";
+        // export { something } from "os";"#,
+        //       Some(serde_json::json!([{ "includeExports": true }])),
+        //   ),
+        //   (
+        //       r#"import os from "os";
+        // export * as os from "os";"#,
+        //       Some(serde_json::json!([{ "includeExports": true }])),
+        //   ),
+        //   (
+        //       r#"export * as os from "os";
+        // import os from "os";"#,
+        //       Some(serde_json::json!([{ "includeExports": true }])),
+        //   ),
+        //   (
+        //       r#"import * as modns from "mod";
+        // export * as  modns from "mod";"#,
+        //       Some(serde_json::json!([{ "includeExports": true }])),
+        //   ),
+        //   (
+        //       r#"export * from "os";
+        // export * from "os";"#,
+        //       Some(serde_json::json!([{ "includeExports": true }])),
+        //   ),
+        //   (
+        //       r#"import "os";
+        // export * from "os";"#,
+        //       Some(serde_json::json!([{ "includeExports": true }])),
+        //   ),
+    ];
+
+    Tester::new(NoDuplicateImports::NAME, pass, fail).test_and_snapshot();
+}

crates/oxc_linter/src/snapshots/no_duplicate_imports.snap

@@ -0,0 +1,44 @@
+---
+source: crates/oxc_linter/src/tester.rs
+snapshot_kind: text
+---
+  ⚠ eslint(no-duplicate-imports): 'fs' import is duplicated
+   ╭─[no_duplicate_imports.tsx:2:7]
+ 1 │ import "fs";
+ 2 │             import "fs"
+   ·             ───────────
+   ╰────
+  help: Merge the duplicated import into a single import statement
+
+  ⚠ eslint(no-duplicate-imports): 'lodash-es' import is duplicated
+   ╭─[no_duplicate_imports.tsx:2:7]
+ 1 │ import { merge } from "lodash-es";
+ 2 │             import { find } from "lodash-es";
+   ·             ─────────────────────────────────
+   ╰────
+  help: Merge the duplicated import into a single import statement
+
+  ⚠ eslint(no-duplicate-imports): 'lodash-es' import is duplicated
+   ╭─[no_duplicate_imports.tsx:2:9]
+ 1 │ import { merge } from "lodash-es";
+ 2 │         import _ from "lodash-es";
+   ·         ──────────────────────────
+   ╰────
+  help: Merge the duplicated import into a single import statement
+
+  ⚠ eslint(no-duplicate-imports): 'os' import is duplicated
+   ╭─[no_duplicate_imports.tsx:2:9]
+ 1 │ import os from "os";
+ 2 │         import { something } from "os";
+   ·         ───────────────────────────────
+ 3 │         import * as foobar from "os";
+   ╰────
+  help: Merge the duplicated import into a single import statement
+
+  ⚠ eslint(no-duplicate-imports): 'lodash-es' import is duplicated
+   ╭─[no_duplicate_imports.tsx:3:9]
+ 2 │         import { merge } from "lodash-es";
+ 3 │         import { baz } from "lodash-es";
+   ·         ────────────────────────────────
+   ╰────
+  help: Merge the duplicated import into a single import statement