From 270f59b3630ef009f4a3e973581b3fc65a24ecc9 Mon Sep 17 00:00:00 2001
From: Googler <noreply@google.com>
Date: Mon, 11 Jul 2016 17:22:55 +0000
Subject: RELNOTES: Improve Android split transition handling.

--
MOS_MIGRATED_REVID=127099896
---
 .../devtools/build/lib/analysis/RuleContext.java   | 34 +++++++++-------------
 1 file changed, 13 insertions(+), 21 deletions(-)

(limited to 'src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java')

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
index d946aae9a0..dc6064c485 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/RuleContext.java
@@ -16,6 +16,7 @@ package com.google.devtools.build.lib.analysis;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Joiner;
+import com.google.common.base.Optional;
 import com.google.common.base.Predicate;
 import com.google.common.base.Predicates;
 import com.google.common.collect.ImmutableBiMap;
@@ -661,8 +662,8 @@ public final class RuleContext extends TargetContext
       // deeply nested and we can't easily inject the behavior we want. However, we should fix all
       // such call sites.
       checkAttribute(attributeName, Mode.SPLIT);
-      Map<String, ? extends List<? extends TransitiveInfoCollection>> map =
-          getSplitPrerequisites(attributeName, /*requireSplit=*/false);
+      Map<Optional<String>, ? extends List<? extends TransitiveInfoCollection>> map =
+          getSplitPrerequisites(attributeName);
       return map.isEmpty()
           ? ImmutableList.<TransitiveInfoCollection>of()
           : map.entrySet().iterator().next().getValue();
@@ -673,16 +674,12 @@ public final class RuleContext extends TargetContext
   }
 
   /**
-   * Returns the a prerequisites keyed by the CPU of their configurations; this method throws an
-   * exception if the split transition is not active.
+   * Returns the a prerequisites keyed by the CPU of their configurations.
+   * If no cpu is explicitly specified, an empty Optional is the only key.
+   * This method throws if the attribute cannot split.
    */
-  public Map<String, ? extends List<? extends TransitiveInfoCollection>>
+  public Map<Optional<String>, ? extends List<? extends TransitiveInfoCollection>>
       getSplitPrerequisites(String attributeName) {
-    return getSplitPrerequisites(attributeName, /*requireSplit*/true);
-  }
-
-  private Map<String, ? extends List<? extends TransitiveInfoCollection>>
-      getSplitPrerequisites(String attributeName, boolean requireSplit) {
     checkAttribute(attributeName, Mode.SPLIT);
 
     Attribute attributeDefinition = getAttribute(attributeName);
@@ -693,15 +690,10 @@ public final class RuleContext extends TargetContext
       // There are two cases here:
       // 1. Splitting is enabled, but only one target cpu.
       // 2. Splitting is disabled, and no --cpu value was provided on the command line.
-      // In the first case, the cpu value is non-null, but in the second case it is null. We only
-      // allow that to proceed if the caller specified that he is going to ignore the cpu value
-      // anyway.
+      // In the first case, the cpu value is non-null, but in the second case it is null.
+      // If --cpu was null, we use an empty Optional in the map.
       String cpu = configurations.get(0).getCpu();
-      if (cpu == null) {
-        Preconditions.checkState(!requireSplit);
-        cpu = "DO_NOT_USE";
-      }
-      return ImmutableMap.of(cpu, targetMap.get(attributeName));
+      return ImmutableMap.of(Optional.fromNullable(cpu), targetMap.get(attributeName));
     }
 
     Set<String> cpus = new HashSet<>();
@@ -713,15 +705,15 @@ public final class RuleContext extends TargetContext
     }
 
     // Use an ImmutableListMultimap.Builder here to preserve ordering.
-    ImmutableListMultimap.Builder<String, TransitiveInfoCollection> result =
+    ImmutableListMultimap.Builder<Optional<String>, TransitiveInfoCollection> result =
         ImmutableListMultimap.builder();
     for (TransitiveInfoCollection t : targetMap.get(attributeName)) {
       if (t.getConfiguration() != null) {
-        result.put(t.getConfiguration().getCpu(), t);
+        result.put(Optional.of(t.getConfiguration().getCpu()), t);
       } else {
         // Source files don't have a configuration, so we add them to all architecture entries.
         for (String cpu : cpus) {
-          result.put(cpu, t);
+          result.put(Optional.of(cpu), t);
         }
       }
     }
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