From 8ff6f2cb860419e9e293f04868955f470a730c9e Mon Sep 17 00:00:00 2001
From: DonIsaac <22823424+DonIsaac@users.noreply.github.com>
Date: Sun, 25 Aug 2024 21:26:45 +0000
Subject: [PATCH] fix(linter/no-unused-vars): panic on UsingDeclarations
 (#5206)

Closes #5202
---
 .../eslint/no_unused_vars/fixers/fix_vars.rs  | 34 +++++++++++++------
 .../rules/eslint/no_unused_vars/tests/oxc.rs  | 10 ++++++
 .../no_unused_vars@oxc-vars-using.snap        | 10 ++++++
 3 files changed, 44 insertions(+), 10 deletions(-)
 create mode 100644 crates/oxc_linter/src/snapshots/no_unused_vars@oxc-vars-using.snap

diff --git a/crates/oxc_linter/src/rules/eslint/no_unused_vars/fixers/fix_vars.rs b/crates/oxc_linter/src/rules/eslint/no_unused_vars/fixers/fix_vars.rs
index dac197a6c2c8a..e4e03d44b731e 100644
--- a/crates/oxc_linter/src/rules/eslint/no_unused_vars/fixers/fix_vars.rs
+++ b/crates/oxc_linter/src/rules/eslint/no_unused_vars/fixers/fix_vars.rs
@@ -34,10 +34,26 @@ impl NoUnusedVars {
             return fixer.noop();
         }
 
-        let Some(AstKind::VariableDeclaration(declaration)) =
-            symbol.nodes().parent_node(decl_id).map(AstNode::kind)
-        else {
-            panic!("VariableDeclarator nodes should always be direct children of VariableDeclaration nodes");
+        let Some(parent) = symbol.nodes().parent_node(decl_id).map(AstNode::kind) else {
+            #[cfg(debug_assertions)]
+            panic!("VariableDeclarator nodes should always have a parent node");
+            #[cfg(not(debug_assertions))]
+            return fixer.noop();
+        };
+        let (span, declarations) = match parent {
+            AstKind::VariableDeclaration(decl) => (decl.span, &decl.declarations),
+            AstKind::UsingDeclaration(decl) => {
+                if decl.is_await {
+                    return fixer.noop();
+                }
+                (decl.span, &decl.declarations)
+            }
+            _ => {
+                #[cfg(debug_assertions)]
+                panic!("VariableDeclarator nodes should always be direct children of VariableDeclaration or UsingDeclaration nodes");
+                #[cfg(not(debug_assertions))]
+                return fixer.noop();
+            }
         };
 
         // `true` even if references aren't considered a usage.
@@ -48,18 +64,16 @@ impl NoUnusedVars {
             // for `let x = 1;` or `const { x } = obj; the whole declaration can
             // be removed, but for `const { x, y } = obj;` or `let x = 1, y = 2`
             // we need to keep the other declarations
-            let has_neighbors = declaration.declarations.len() > 1;
-            debug_assert!(!declaration.declarations.is_empty());
+            let has_neighbors = declarations.len() > 1;
+            debug_assert!(!declarations.is_empty());
             let binding_info = symbol.get_binding_info(&decl.id.kind);
 
             match binding_info {
                 BindingInfo::SingleDestructure | BindingInfo::NotDestructure => {
                     if has_neighbors {
-                        return symbol
-                            .delete_from_list(fixer, &declaration.declarations, decl)
-                            .dangerously();
+                        return symbol.delete_from_list(fixer, declarations, decl).dangerously();
                     }
-                    return fixer.delete(declaration).dangerously();
+                    return fixer.delete_range(span).dangerously();
                 }
                 BindingInfo::MultiDestructure(mut span, is_object, is_last) => {
                     let source_after = &fixer.source_text()[(span.end as usize)..];
diff --git a/crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs b/crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs
index 6e672a4317275..ebe11f0f0c495 100644
--- a/crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs
+++ b/crates/oxc_linter/src/rules/eslint/no_unused_vars/tests/oxc.rs
@@ -370,6 +370,16 @@ fn test_vars_catch() {
         .test_and_snapshot();
 }
 
+#[test]
+fn test_vars_using() {
+    let pass = vec![("using a = 1; console.log(a)", None)];
+
+    let fail = vec![("using a = 1;", None)];
+
+    Tester::new(NoUnusedVars::NAME, pass, fail)
+        .with_snapshot_suffix("oxc-vars-using")
+        .test_and_snapshot();
+}
 #[test]
 fn test_functions() {
     let pass = vec![
diff --git a/crates/oxc_linter/src/snapshots/no_unused_vars@oxc-vars-using.snap b/crates/oxc_linter/src/snapshots/no_unused_vars@oxc-vars-using.snap
new file mode 100644
index 0000000000000..9db7ba5c13c99
--- /dev/null
+++ b/crates/oxc_linter/src/snapshots/no_unused_vars@oxc-vars-using.snap
@@ -0,0 +1,10 @@
+---
+source: crates/oxc_linter/src/tester.rs
+---
+  ⚠ eslint(no-unused-vars): Variable 'a' is declared but never used.
+   ╭─[no_unused_vars.tsx:1:7]
+ 1 │ using a = 1;
+   ·       ┬
+   ·       ╰── 'a' is declared here
+   ╰────
+  help: Consider removing this declaration.