[NTI] Fix crash related to properties of unknown THIS.

Fixes #2538 on github. ------------- Created by MOE: https://github.com/google/moe MOE_MIGRATED_REVID=160576845
google · Jun 30, 2017 · 9e26885 · 9e26885
1 parent 9b55459
commit 9e26885
Show file tree

Hide file tree

Showing 2 changed files with 14 additions and 3 deletions.
diff --git a/src/com/google/javascript/jscomp/NewTypeInference.java b/src/com/google/javascript/jscomp/NewTypeInference.java
@@ -3382,6 +3382,11 @@ private TypeEnv updateLvalueTypeInEnv(
           String objName = qname.getLeftmostName();
           QualifiedName props = qname.getAllButLeftmost();
           JSType objType = envGetType(env, objName);
+          if (objType == null) {
+            // Don't specialize THIS properties in functions where THIS is unknown.
+            checkState(objName.equals("this"));
+            return env;
+          }
           // TODO(dimvar): In analyzeNameFwd/Bwd, we are careful to not
           // specialize namespaces, and we need the same check here. But
           // currently, stopping specialization here causes tests to fail,
@@ -4307,8 +4312,7 @@ private EnvTypePair mayWarnAboutNullableReferenceAndTighten(
       JSType minusNull = recvType.removeType(NULL_OR_UNDEFINED);
       if (!minusNull.isBottom()) {
         if (this.reportNullDeref) {
-          warnings.add(JSError.make(
-              obj, NULLABLE_DEREFERENCE, recvType.toString()));
+          warnings.add(JSError.make(obj, NULLABLE_DEREFERENCE, recvType.toString()));
         }
         TypeEnv outEnv = inEnv;
         if (obj.isQualifiedName()) {

diff --git a/test/com/google/javascript/jscomp/NewTypeInferenceTest.java b/test/com/google/javascript/jscomp/NewTypeInferenceTest.java
@@ -246,7 +246,7 @@ public void testNewInFunctionJsdoc() {
         NewTypeInference.INEXISTENT_PROPERTY);
   }
 
-  public void testAlhpaRenamingDoesntChangeType() {
+  public void testAlphaRenamingDoesntChangeType() {
     typeCheck(LINE_JOINER.join(
         "/**",
         " * @param {U} x",
@@ -20855,4 +20855,11 @@ public void testPrintTypevarIDs() {
             "Expected a supertype of : T#1",
             "but found               : T#2"));
   }
+
+  public void testDontCrashOnKnownPropertyOfGlobalThis() {
+    typeCheck(
+        "function f(){ this.constructor['fubar'] = 1; }",
+        NewTypeInference.NULLABLE_DEREFERENCE,
+        NewTypeInference.GLOBAL_THIS);
+  }
 }