fix(linter/eslint/no-unassigned-vars): skip Svelte and Vue files

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

@@ -23,6 +23,14 @@ declare_oxc_lint!(
     ///
     /// Disallow let or var variables that are read but never assigned.
     ///
+    /// #### Ignored Files
+    /// This rule ignores `.svelte` and `.vue` files entirely. Oxlint only parses the
+    /// `<script>` blocks of these files, so a binding that the template assigns looks
+    /// like it is never assigned. In Svelte the template writes through
+    /// `bind:this={el}` and `bind:value={x}`; in Vue a `<script setup>` `let` is a
+    /// `setup-let` binding that `v-model="x"` and inline handlers such as
+    /// `@click="x = 1"` assign to directly.
+    ///
     /// ### Why is this bad?
     ///
     /// This rule flags let or var declarations that are never assigned a value but are still read or used in the code.
@@ -103,6 +111,11 @@ impl Rule for NoUnassignedVars {
             ctx.diagnostic(no_unassigned_vars_diagnostic(ident.span, ident.name.as_str()));
         }
     }
+
+    fn should_run(&self, ctx: &crate::context::ContextHost) -> bool {
+        // ignore svelte/vue: their templates can assign a binding, which we can't see.
+        !ctx.file_extension().is_some_and(|ext| ext == "svelte" || ext == "vue")
+    }
 }
 
 #[test]
@@ -160,3 +173,61 @@ fn test() {
 
     Tester::new(NoUnassignedVars::NAME, NoUnassignedVars::PLUGIN, pass, fail).test_and_snapshot();
 }
+
+#[test]
+fn test_svelte() {
+    use crate::tester::Tester;
+
+    // The markup is stripped before linting; it documents the template-side write
+    // (`bind:this`, `bind:value`) that makes these bindings assigned in reality.
+    let pass = vec![
+        "<script lang=\"ts\">
+            let dialog: HTMLDialogElement;
+            function openDialog() { dialog.showModal(); }
+         </script>
+         <dialog bind:this={dialog}></dialog>",
+        "<script>
+            let value;
+            log(value);
+         </script>
+         <input bind:value />",
+        // Both blocks of a two-script component are linted; neither may report.
+        "<script module>
+            let shared;
+            log(shared);
+         </script>
+         <script>
+            let value;
+            log(value);
+         </script>
+         <input bind:value />",
+    ];
+
+    Tester::new(NoUnassignedVars::NAME, NoUnassignedVars::PLUGIN, pass, vec![])
+        .change_rule_path("test.svelte")
+        .test();
+}
+
+#[test]
+fn test_vue() {
+    use crate::tester::Tester;
+
+    // A `<script setup>` `let` is a `setup-let` binding: `v-model` and inline handlers
+    // compile to direct assignments to it, so the script alone cannot see the write.
+    let pass = vec![
+        "<script setup>
+            let msg;
+            log(msg);
+         </script>
+         <template><input v-model=\"msg\" /></template>",
+        "<script setup>
+            let count;
+            log(count);
+         </script>
+         <template><button @click=\"count = 1\">go</button></template>",
+    ];
+
+    Tester::new(NoUnassignedVars::NAME, NoUnassignedVars::PLUGIN, pass, vec![])
+        .change_rule_path("test.vue")
+        .test();
+}