fix: initializing class in static method counts as usage (#1259)

Author: tobias47n9e

src/rules/no_unused_vars.rs

@@ -306,6 +306,12 @@ impl Visit for Collector {
         }
         AssignTarget::Pat(_) => n.visit_children_with(self),
       }
+
+      if let Expr::New(new_expr) = &*n.right {
+        self.without_cur_defining(|a| {
+          new_expr.visit_children_with(a);
+        });
+      }
     } else {
       n.visit_children_with(self)
     }
@@ -849,6 +855,7 @@ mod tests {
       "function foo(cb) { var b; cb = b = function(a) { cb(1 + a); }; b(); } foo();",
       "(class { set foo(UNUSED) {} })",
       "class Foo { set bar(UNUSED) {} } console.log(Foo)",
+      "let foo; class Foo { instance; static { foo = new Foo(); } } foo.toString();",
       "var a = function () { a(); }; a();",
       "var a = function(){ return function () { a(); } }; a();",
       "const a = () => { a(); }; a();",
@@ -2379,6 +2386,27 @@ export const Foo = () => {
     };
   }
 
+  #[test]
+  fn no_unused_vars_static_init_is_usage() {
+    assert_lint_err! {
+      NoUnusedVars,
+      "let foo: Foo;
+class Foo {
+  instance;
+  static {
+    foo = new Foo();
+  }
+}
+": [
+        {
+          col: 4,
+          message: variant!(NoUnusedVarsMessage, NeverUsed, "foo"),
+          hint: variant!(NoUnusedVarsHint, AddPrefix, "foo"),
+        }
+      ],
+    };
+  }
+
   // TODO(magurotuna): deals with this using ControlFlow
   #[test]
   #[ignore = "control flow analysis is not implemented yet"]