Be less naive with CcLibraryHelper precompiled library collision detection.

The naive algorithm was O(n*m) where n = number of precompiled libraries and
m = number of libraries linked during this rule. Ugly!

This one provides hopefully much more reasonable performance.

--
MOS_MIGRATED_REVID=128206057

1 files changed, 9 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/util/FileType.java b/src/main/java/com/google/devtools/build/lib/util/FileType.java
index b8b4fdc119..b984e98d70 100644
--- a/src/main/java/com/google/devtools/build/lib/util/FileType.java
+++ b/src/main/java/com/google/devtools/build/lib/util/FileType.java
@@ -14,6 +14,7 @@
 
 package com.google.devtools.build.lib.util;
 
+import com.google.common.base.Function;
 import com.google.common.base.Predicate;
 import com.google.common.base.Predicates;
 import com.google.common.collect.ImmutableList;
@@ -129,6 +130,14 @@ public abstract class FileType implements Predicate<String> {
     String getFilename();
   }
 
+  public static final Function<HasFilename, String> TO_FILENAME =
+      new Function<HasFilename, String>() {
+        @Override
+        public String apply(HasFilename input) {
+          return input.getFilename();
+        }
+      };
+
   /**
    * Checks whether an Iterable<? extends HasFileType> contains any of the specified file types.
    *