1 files changed, 15 insertions, 7 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/actions/ActionEnvironment.java b/src/main/java/com/google/devtools/build/lib/actions/ActionEnvironment.java
index ba39e801ee..d074c399de 100644
--- a/src/main/java/com/google/devtools/build/lib/actions/ActionEnvironment.java
+++ b/src/main/java/com/google/devtools/build/lib/actions/ActionEnvironment.java
@@ -42,7 +42,8 @@ public final class ActionEnvironment {
    */
   // TODO(ulfjack): Migrate all production code to use the proper action environment, and then make
   // this @VisibleForTesting or rename it to clarify.
-  public static final ActionEnvironment EMPTY = new ActionEnvironment(ImmutableMap.of());
+  public static final ActionEnvironment EMPTY =
+      new ActionEnvironment(ImmutableMap.of(), ImmutableSet.of());
 
   /**
    * Splits the given map into a map of variables with a fixed value, and a set of variables that
@@ -62,24 +63,31 @@ public final class ActionEnvironment {
         inheritedEnv.add(key);
       }
     }
-    return new ActionEnvironment(fixedEnv, inheritedEnv);
+    return create(fixedEnv, inheritedEnv);
   }
 
   private final ImmutableMap<String, String> fixedEnv;
   private final ImmutableSet<String> inheritedEnv;
 
+  private ActionEnvironment(Map<String, String> fixedEnv, Set<String> inheritedEnv) {
+    this.fixedEnv = ImmutableMap.copyOf(fixedEnv);
+    this.inheritedEnv = ImmutableSet.copyOf(inheritedEnv);
+  }
+
   /**
    * Creates a new action environment. The order in which the environments are combined is
    * undefined, so callers need to take care that the key set of the {@code fixedEnv} map and the
    * set of {@code inheritedEnv} elements are disjoint.
    */
-  public ActionEnvironment(Map<String, String> fixedEnv, Set<String> inheritedEnv) {
-    this.fixedEnv = ImmutableMap.copyOf(fixedEnv);
-    this.inheritedEnv = ImmutableSet.copyOf(inheritedEnv);
+  public static ActionEnvironment create(Map<String, String> fixedEnv, Set<String> inheritedEnv) {
+    if (fixedEnv.isEmpty() && inheritedEnv.isEmpty()) {
+      return EMPTY;
+    }
+    return new ActionEnvironment(fixedEnv, inheritedEnv);
   }
 
-  public ActionEnvironment(Map<String, String> fixedEnv) {
-    this(fixedEnv, ImmutableSet.of());
+  public static ActionEnvironment create(Map<String, String> fixedEnv) {
+    return new ActionEnvironment(fixedEnv, ImmutableSet.of());
   }
 
   public ImmutableMap<String, String> getFixedEnv() {