feat(linter): add vue/require-default-export rule

crates/oxc_linter/src/context/host.rs

@@ -96,6 +96,11 @@ impl<'a> ContextSubHost<'a> {
     pub fn disable_directives(&self) -> &DisableDirectives {
         &self.disable_directives
     }
+
+    /// Shared reference to the [`FrameworkOptions`]
+    pub fn framework_options(&self) -> FrameworkOptions {
+        self.framework_options
+    }
 }
 
 /// Stores shared information about a file being linted.

crates/oxc_linter/src/generated/rule_runner_impls.rs

@@ -2937,6 +2937,10 @@ impl RuleRunner for crate::rules::vue::prefer_import_from_vue::PreferImportFromV
     const NODE_TYPES: Option<&AstTypesBitset> = None;
 }
 
+impl RuleRunner for crate::rules::vue::require_default_export::RequireDefaultExport {
+    const NODE_TYPES: Option<&AstTypesBitset> = None;
+}
+
 impl RuleRunner for crate::rules::vue::require_typed_ref::RequireTypedRef {
     const NODE_TYPES: Option<&AstTypesBitset> =
         Some(&AstTypesBitset::from_types(&[AstType::CallExpression]));

crates/oxc_linter/src/rules.rs

@@ -650,6 +650,7 @@ pub(crate) mod vue {
     pub mod no_multiple_slot_args;
     pub mod no_required_prop_with_default;
     pub mod prefer_import_from_vue;
+    pub mod require_default_export;
     pub mod require_typed_ref;
     pub mod valid_define_emits;
     pub mod valid_define_props;
@@ -1256,6 +1257,7 @@ oxc_macros::declare_all_lint_rules! {
     vue::no_multiple_slot_args,
     vue::no_required_prop_with_default,
     vue::prefer_import_from_vue,
+    vue::require_default_export,
     vue::require_typed_ref,
     vue::valid_define_emits,
     vue::valid_define_props,

crates/oxc_linter/src/rules/vue/require_default_export.rs

@@ -0,0 +1,269 @@
+use oxc_ast::{AstKind, ast::Expression};
+use oxc_diagnostics::OxcDiagnostic;
+use oxc_macros::declare_oxc_lint;
+use oxc_span::Span;
+
+use crate::{
+    context::{ContextHost, LintContext},
+    frameworks::FrameworkOptions,
+    rule::Rule,
+};
+
+fn missing_default_export_diagnostic(span: Span) -> OxcDiagnostic {
+    OxcDiagnostic::warn("Missing default export.").with_label(span)
+}
+
+fn must_be_default_export_diagnostic(span: Span) -> OxcDiagnostic {
+    OxcDiagnostic::warn("Component must be the default export.").with_label(span)
+}
+
+#[derive(Debug, Default, Clone)]
+pub struct RequireDefaultExport;
+
+declare_oxc_lint!(
+    /// ### What it does
+    ///
+    /// Require components to be the default export.
+    ///
+    /// ### Why is this bad?
+    ///
+    /// Using SFCs (Single File Components) without a default export is
+    /// not supported in Vue 3. Components should be exported as the default export.
+    ///
+    /// ### Examples
+    ///
+    /// Examples of **incorrect** code for this rule:
+    /// ```vue
+    /// <script>
+    /// const foo = 'foo';
+    /// </script>
+    /// ```
+    ///
+    /// Examples of **correct** code for this rule:
+    /// ```vue
+    /// <script>
+    /// export default {
+    ///   data() {
+    ///     return {
+    ///       foo: 'foo'
+    ///     };
+    ///   }
+    /// };
+    /// </script>
+    /// ```
+    RequireDefaultExport,
+    vue,
+    suspicious,
+);
+
+impl Rule for RequireDefaultExport {
+    fn run_once(&self, ctx: &LintContext) {
+        let has_define_component = ctx.nodes().iter().any(|node| {
+            let AstKind::CallExpression(call_expr) = node.kind() else {
+                return false;
+            };
+
+            match call_expr.callee.get_inner_expression() {
+                Expression::Identifier(identifier) => identifier.name == "defineComponent",
+                Expression::StaticMemberExpression(member_expr) => {
+                    let Expression::Identifier(object_identifier) =
+                        member_expr.object.get_inner_expression()
+                    else {
+                        return false;
+                    };
+
+                    object_identifier.name == "Vue" && member_expr.property.name == "component"
+                }
+                _ => false,
+            }
+        });
+
+        #[expect(clippy::cast_possible_truncation)]
+        let span = Span::sized(
+            ctx.source_text().len() as u32,
+            9, // `</script>` length
+        );
+
+        if has_define_component {
+            ctx.diagnostic(must_be_default_export_diagnostic(span));
+        } else {
+            ctx.diagnostic(missing_default_export_diagnostic(span));
+        }
+    }
+
+    fn should_run(&self, ctx: &ContextHost) -> bool {
+        // only on vue files
+        if ctx.file_path().extension().is_none_or(|ext| ext != "vue") {
+            return false;
+        }
+
+        // only with `<script>`, not `<script setup>`
+        if ctx.frameworks_options() == FrameworkOptions::VueSetup {
+            return false;
+        }
+
+        // only when no default export is present
+        if ctx.module_record().export_default.is_some() {
+            return false;
+        }
+
+        // only when no `<script setup>` is present in the current file
+        !ctx.other_file_hosts()
+            .iter()
+            .any(|host| host.framework_options() == FrameworkOptions::VueSetup)
+    }
+}
+
+#[test]
+fn test() {
+    use crate::tester::Tester;
+    use std::path::PathBuf;
+
+    let pass = vec![
+        (
+            "
+			      <template>Without script</template>
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.vue")),
+        ),
+        (
+            "
+			      <script>
+			        import { ref } from 'vue';
+
+			        export default {}
+			      </script>
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.vue")),
+        ),
+        (
+            "
+			      <script setup>
+			        const foo = 'foo';
+			      </script>
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.vue")),
+        ),
+        (
+            "
+			      <script>
+			      const component = {};
+
+			      export default component;
+			      </script>
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.vue")),
+        ),
+        (
+            "
+			      <script>
+			      import {defineComponent} from 'vue';
+
+			      export default defineComponent({});
+			      </script>
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.vue")),
+        ),
+        (
+            "
+			      const foo = 'foo';
+			      export const bar = 'bar';
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.js")),
+        ),
+        (
+            "
+			      import {defineComponent} from 'vue';
+			      defineComponent({});
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.js")),
+        ),
+    ];
+
+    let fail = vec![
+        (
+            "
+			      <script>
+			      const foo = 'foo';
+			      </script>
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.vue")),
+        ),
+        (
+            "
+			      <script>
+			      export const foo = 'foo';
+			      </script>
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.vue")),
+        ),
+        (
+            "
+			      <script>
+			      const foo = 'foo';
+
+			      export { foo };
+			      </script>
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.vue")),
+        ),
+        (
+            "
+			      <script>
+			      export const foo = 'foo';
+			      export const bar = 'bar';
+			      </script>
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.vue")),
+        ),
+        (
+            "
+			      <script>
+			      import { defineComponent } from 'vue';
+
+			      export const component = defineComponent({});
+			      </script>
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.vue")),
+        ),
+        (
+            "
+			      <script>
+			      import Vue from 'vue';
+
+			      const component = Vue.component('foo', {});
+			      </script>
+			      ",
+            None,
+            None,
+            Some(PathBuf::from("test.vue")),
+        ),
+    ];
+
+    Tester::new(RequireDefaultExport::NAME, RequireDefaultExport::PLUGIN, pass, fail)
+        .test_and_snapshot();
+}

crates/oxc_linter/src/snapshots/vue_require_default_export.snap

@@ -0,0 +1,50 @@
+---
+source: crates/oxc_linter/src/tester.rs
+---
+  ⚠ eslint-plugin-vue(require-default-export): Missing default export.
+   ╭─[require_default_export.tsx:4:10]
+ 3 │                   const foo = 'foo';
+ 4 │                   </script>
+   ·                   ─────────
+ 5 │                   
+   ╰────
+
+  ⚠ eslint-plugin-vue(require-default-export): Missing default export.
+   ╭─[require_default_export.tsx:4:10]
+ 3 │                   export const foo = 'foo';
+ 4 │                   </script>
+   ·                   ─────────
+ 5 │                   
+   ╰────
+
+  ⚠ eslint-plugin-vue(require-default-export): Missing default export.
+   ╭─[require_default_export.tsx:6:10]
+ 5 │                   export { foo };
+ 6 │                   </script>
+   ·                   ─────────
+ 7 │                   
+   ╰────
+
+  ⚠ eslint-plugin-vue(require-default-export): Missing default export.
+   ╭─[require_default_export.tsx:5:10]
+ 4 │                   export const bar = 'bar';
+ 5 │                   </script>
+   ·                   ─────────
+ 6 │                   
+   ╰────
+
+  ⚠ eslint-plugin-vue(require-default-export): Component must be the default export.
+   ╭─[require_default_export.tsx:6:10]
+ 5 │                   export const component = defineComponent({});
+ 6 │                   </script>
+   ·                   ─────────
+ 7 │                   
+   ╰────
+
+  ⚠ eslint-plugin-vue(require-default-export): Component must be the default export.
+   ╭─[require_default_export.tsx:6:10]
+ 5 │                   const component = Vue.component('foo', {});
+ 6 │                   </script>
+   ·                   ─────────
+ 7 │                   
+   ╰────