LTO: Don't choke on cc_library without srcs.

--
MOS_MIGRATED_REVID=105204997

2 files changed, 7 insertions, 2 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkAction.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkAction.java
index 4d412e983c..36c197bda6 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkAction.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/CppLinkAction.java
@@ -642,6 +642,9 @@ public final class CppLinkAction extends AbstractAction {
       // this is O(M*N). If we had a nested set of .o files, we could have O(M + N) instead.
       NestedSetBuilder<Artifact> bitcodeBuilder = NestedSetBuilder.stableOrder();
       for (LibraryToLink lib : uniqueLibraries) {
+        if (!lib.containsObjectFiles()) {
+          continue;
+        }
         for (Artifact a : lib.getObjectFiles()) {
           if (compiled.contains(a)) {
             bitcodeBuilder.add(a);
diff --git a/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkerInputs.java b/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkerInputs.java
index 21e4146c63..1d33e637d7 100644
--- a/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkerInputs.java
+++ b/src/main/java/com/google/devtools/build/lib/rules/cpp/LinkerInputs.java
@@ -150,7 +150,7 @@ public abstract class LinkerInputs {
 
     @Override
     public Iterable<Artifact> getLTOBitcodeFiles() {
-      return ImmutableList.<Artifact>of();
+      return ImmutableList.of();
     }
 
     @Override
@@ -212,7 +212,9 @@ public abstract class LinkerInputs {
       this.libraryArtifact = Preconditions.checkNotNull(libraryArtifact);
       this.objectFiles = objectFiles == null ? null : CollectionUtils.makeImmutable(objectFiles);
       this.ltoBitcodeFiles =
-          (ltoBitcodeFiles == null) ? null : CollectionUtils.makeImmutable(ltoBitcodeFiles);
+          (ltoBitcodeFiles == null)
+              ? ImmutableList.<Artifact>of()
+              : CollectionUtils.makeImmutable(ltoBitcodeFiles);
     }
 
     @Override