Prevent escope referencer from traversing into param pattern type ann…

…otations

index.js

@@ -47,17 +47,23 @@ function monkeypatch() {
     estraverseRelative = createModule(esrecurseLoc);
   } catch (err) {}
 
+  // contains all the instances of estraverse so we can modify them if necessary
+  var estraverses = [];
+
   // monkeypatch estraverse
   estraverse = estraverseRelative.require("estraverse");
+  estraverses.push(estraverse);
   assign(estraverse.VisitorKeys, t.VISITOR_KEYS);
 
   // monkeypatch estraverse-fb
   var estraverseFb = eslintMod.require("estraverse-fb");
+  estraverses.push(estraverseFb);
   assign(estraverseFb.VisitorKeys, t.VISITOR_KEYS);
 
   // ESLint v1.9.0 uses estraverse directly to work around https://github.com/npm/npm/issues/9663
   var estraverseOfEslint = eslintMod.require("estraverse");
   if (estraverseOfEslint !== estraverseFb) {
+    estraverses.push(estraverseOfEslint);
     assign(estraverseOfEslint.VisitorKeys, t.VISITOR_KEYS);
   }
 
@@ -279,7 +285,18 @@ function monkeypatch() {
         }
       }
     }
+    // set ArrayPattern/ObjectPattern visitor keys back to their original. otherwise
+    // escope will traverse into them and include the identifiers within as declarations
+    estraverses.forEach(function (estraverse) {
+      estraverse.VisitorKeys.ObjectPattern = ["properties"];
+      estraverse.VisitorKeys.ArrayPattern = ["elements"];
+    });
     visitFunction.call(this, node);
+    // set them back to normal...
+    estraverses.forEach(function (estraverse) {
+      estraverse.VisitorKeys.ObjectPattern = t.VISITOR_KEYS.ObjectPattern;
+      estraverse.VisitorKeys.ObjectPattern = t.VISITOR_KEYS.ArrayPattern;
+    });
     if (typeParamScope) {
       this.close(node);
     }

test/non-regression.js

@@ -1340,6 +1340,20 @@ describe("verify", function () {
     );
   });
 
+  it("", function () {
+
+    verifyAndAssertMessages([
+        "import type Foo from 'bar';",
+        "class Foobar {",
+        "  foo({ bar }: Foo) {}",
+        "  bar({ foo }: Foo) {}",
+        "}"
+      ].join("\n"),
+      { "no-unused-vars": 1 },
+      []
+    );
+  });
+
   // it("regex with es6 unicodeCodePointEscapes", function () {
   //   verifyAndAssertMessages(
   //     "string.replace(/[\u{0000A0}-\u{10FFFF}<>\&]/gmiu, (char) => `&#x${char.codePointAt(0).toString(16)};`);",