Deopt evaluation of undefined with a local binding. Fix #5204 (#5206)

babel · May 19, 2017 · d92c745 · d92c745
1 parent c89a22e
commit d92c745
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Showing 2 changed files with 21 additions and 3 deletions.
diff --git a/packages/babel-traverse/src/path/evaluation.js b/packages/babel-traverse/src/path/evaluation.js
@@ -176,11 +176,11 @@ export function evaluate(): { confident: boolean; value: any } {
         return binding.value;
       } else {
         if (node.name === "undefined") {
-          return undefined;
+          return binding ? deopt(binding.path) : undefined;
         } else if (node.name === "Infinity") {
-          return Infinity;
+          return binding ? deopt(binding.path) : Infinity;
         } else if (node.name === "NaN") {
-          return NaN;
+          return binding ? deopt(binding.path) : NaN;
         }
 
         const resolved = path.resolve();

diff --git a/packages/babel-traverse/test/evaluation.js b/packages/babel-traverse/test/evaluation.js
@@ -101,4 +101,22 @@ describe("evaluation", function () {
       false
     );
   });
+
+  it("should evaluate undefined, NaN and Infinity", () => {
+    assert.strictEqual(getPath("undefined").get("body.0.expression").evaluate().confident, true);
+    assert.strictEqual(getPath("NaN").get("body.0.expression").evaluate().confident, true);
+    assert.strictEqual(getPath("Infinity").get("body.0.expression").evaluate().confident, true);
+  });
+
+  it("should deopt redefined primitives - undefined, NaN and Infinity", () => {
+    const eval_undef = getPath("let undefined; undefined;").get("body.1.expression").evaluate();
+    const eval_nan = getPath("let NaN; NaN;").get("body.1.expression").evaluate();
+    const eval_inf = getPath("let Infinity; Infinity;").get("body.1.expression").evaluate();
+    assert.strictEqual(eval_undef.confident, false);
+    assert.strictEqual(eval_nan.confident, false);
+    assert.strictEqual(eval_inf.confident, false);
+
+    assert.strictEqual(eval_undef.deopt.type, "VariableDeclarator");
+    assert.strictEqual(eval_undef.deopt.parentPath.node.kind, "let");
+  });
 });