Allow heterogeneous lists in Skylark.

This brings consistency between BUILD and Skylark interpreters. It also brings
consistency with dicts (e.g. **kwargs can contain anything and kwargs.values
is allowed).

--
MOS_MIGRATED_REVID=100278980

1 files changed, 3 insertions, 15 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);
   }