2 files changed, 5 insertions, 20 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkList.java b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkList.java
index cbcf21a95c..fb4f2457d4 100644
--- a/src/main/java/com/google/devtools/build/lib/syntax/SkylarkList.java
+++ b/src/main/java/com/google/devtools/build/lib/syntax/SkylarkList.java
@@ -362,23 +362,15 @@ public abstract class SkylarkList implements Iterable<Object> {
     if (elements.isEmpty()) {
       return EMPTY_LIST;
     }
-    return new SimpleSkylarkList(
-        ImmutableList.copyOf(elements), false, getContentType(elements, loc));
+    return new SimpleSkylarkList(ImmutableList.copyOf(elements), false, getContentType(elements));
   }
 
-  private static SkylarkType getContentType(Collection<?> elements, Location loc)
+  private static SkylarkType getContentType(Collection<?> elements)
       throws EvalException {
     SkylarkType type = SkylarkType.TOP;
     for (Object element : elements) {
       SkylarkType elementType = SkylarkType.typeOf(element);
-      SkylarkType inter = SkylarkType.intersection(type, elementType);
-      if (inter == SkylarkType.BOTTOM) {
-        throw new EvalException(loc, String.format(
-            "Incompatible types in list: found a %s but the previous elements were %ss",
-            elementType, type));
-      } else {
-        type = inter;
-      }
+      type = SkylarkType.intersection(type, elementType);
     }
     return type;
   }
@@ -399,10 +391,6 @@ public abstract class SkylarkList implements Iterable<Object> {
       return left;
     }
     SkylarkType type = SkylarkType.intersection(left.contentType, right.contentType);
-    if (type == SkylarkType.BOTTOM) {
-      throw new EvalException(loc, String.format("cannot concatenate list of %s with list of %s",
-              left.contentType, right.contentType));
-    }
     return new ConcatenatedSkylarkList(left, right, left.isTuple(), type);
   }
 
diff --git a/src/test/java/com/google/devtools/build/lib/syntax/SkylarkEvaluationTest.java b/src/test/java/com/google/devtools/build/lib/syntax/SkylarkEvaluationTest.java
index 744e6db31b..575e0a67d7 100644
--- a/src/test/java/com/google/devtools/build/lib/syntax/SkylarkEvaluationTest.java
+++ b/src/test/java/com/google/devtools/build/lib/syntax/SkylarkEvaluationTest.java
@@ -867,15 +867,12 @@ public class SkylarkEvaluationTest extends EvaluationTest {
 
   @Test
   public void testCannotCreateMixedListInSkylark() throws Exception {
-    new SkylarkTest().update("mock", new Mock()).testIfExactError(
-        "Incompatible types in list: found a int but the previous elements were strings",
-        "[mock.string(), 1, 2]");
+    new SkylarkTest().testExactOrder("['a', 'b', 1, 2]", "a", "b", 1, 2);
   }
 
   @Test
   public void testCannotConcatListInSkylarkWithDifferentGenericTypes() throws Exception {
-    new SkylarkTest().update("mock", new Mock()).testIfExactError(
-        "cannot concatenate list of string with list of int", "mock.string_list() + [1, 2]");
+    new SkylarkTest().testExactOrder("[1, 2] + ['a', 'b']", 1, 2, "a", "b");
   }
 
   @Test