Remove ConfigurationTransitionProxy.NULL

PiperOrigin-RevId: 182099803

1 files changed, 36 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/NullTransition.java b/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/NullTransition.java
new file mode 100644
index 0000000000..2edbb9fb0f
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/transitions/NullTransition.java
@@ -0,0 +1,36 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package com.google.devtools.build.lib.analysis.config.transitions;
+
+import com.google.devtools.build.lib.analysis.config.BuildOptions;
+
+/**
+ * A {@link PatchTransition} to a null configuration.
+ */
+public class NullTransition implements PatchTransition {
+
+  public static final NullTransition INSTANCE = new NullTransition();
+
+  private NullTransition() {
+  }
+
+  @Override
+  public BuildOptions apply(BuildOptions options) {
+    throw new UnsupportedOperationException(
+        "This is only referenced in a few places, so it's easier and more efficient to optimize "
+        + "Blaze's transition logic in the presence of null transitions vs. actually call this "
+        + "method to get results we know ahead of time. If there's ever a need to properly "
+        + "implement this method we can always do so.");
+  }
+}