commit efd7ca1b420e00cf32839c07733e0e4a4d8b1bbb
author Yun Peng <pcloudy@google.com> Thu Mar 03 13:14:38 2016 +0000
committer Kristina Chodorow <kchodorow@google.com> Thu Mar 03 15:28:01 2016 +0000
tree 04eee06d2b6e277f3d0eaa7f326f1ae843b56746
parent f745e99db7632cfb2145b6926f961e85f9084bc5

Python provider is now available in Skylark

Using mandatoryProvidersList to validate python rules' dependency.
Added a SkylarkProvider named 'py' which is a SkylarkClassObject in Java and a
struct in Skylark. Native python rule and Skylark python rule should have this provider
so that they can depend on each other.

RELNOTES[NEW]: Native python rule can depend on skylark rule as long as skylark
rule provides 'py' provider.

--
MOS_MIGRATED_REVID=116241504

src/main/java/com/google/devtools/build/lib/packages/Attribute.java

diff --git a/src/main/java/com/google/devtools/build/lib/packages/Attribute.java b/src/main/java/com/google/devtools/build/lib/packages/Attribute.java
index f8923e7..1db5c46 100644
--- a/src/main/java/com/google/devtools/build/lib/packages/Attribute.java
+++ b/src/main/java/com/google/devtools/build/lib/packages/Attribute.java
@@ -713,7 +713,9 @@
     }
 
     public Builder<TYPE> mandatoryProviders(Iterable<String> providers) {
-      mandatoryProvidersList(ImmutableList.of(providers));
+      if (providers.iterator().hasNext()) {
+        mandatoryProvidersList(ImmutableList.of(providers));
+      }
       return this;
     }