Override BuildConfiguration.equals() for dynamic configs.

This makes tests that unnecessarily relied on reference equality pass
with --experimental_dynamic_configs=notrim. In particular, with
--nodistinct_host_configuration dynamic configurations still use
distinct instances even though the options are the same.

This is a roll forward of original change: https://github.com/bazelbuild/bazel/commit/2a2be3907981d9654575493c7012d95d1241f373

That was rolled back because of lots of expensive hashCode() calls.
This version precomputes the hash code.

--
PiperOrigin-RevId: 141095789
MOS_MIGRATED_REVID=141095789

2 files changed, 32 insertions, 1 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
index 1a7814a0e1..c4689c90f2 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/config/BuildConfiguration.java
@@ -85,6 +85,7 @@ import java.util.LinkedHashSet;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Queue;
 import java.util.Set;
 import java.util.TreeMap;
@@ -1080,6 +1081,8 @@ public final class BuildConfiguration {
   private final ImmutableMap<String, String> testEnvironment;
   private final ImmutableMap<String, String> commandLineBuildVariables;
 
+  private final int hashCode; // We can precompute the hash code as all its inputs are immutable.
+
   /**
    * Helper container for {@link #transitiveOptionsMap} below.
    */
@@ -1140,6 +1143,33 @@ public final class BuildConfiguration {
   }
 
   /**
+   * Returns {@code true} if this configuration is semantically equal to the other, including
+   * checking that both have the same sets of fragments and options.
+   */
+  @Override
+  public boolean equals(Object other) {
+    if (this == other) {
+      return true;
+    }
+    if (!(other instanceof BuildConfiguration)) {
+      return false;
+    }
+    BuildConfiguration otherConfig = (BuildConfiguration) other;
+    return actionsEnabled == otherConfig.actionsEnabled
+        && fragments.values().equals(otherConfig.fragments.values())
+        && buildOptions.getOptions().equals(otherConfig.buildOptions.getOptions());
+  }
+
+  private int computeHashCode() {
+    return Objects.hash(actionsEnabled, fragments, buildOptions.getOptions());
+  }
+
+  @Override
+  public int hashCode() {
+    return hashCode;
+  }
+
+  /**
    * Returns map of all the fragments for this configuration.
    */
   public ImmutableMap<Class<? extends Fragment>, Fragment> getAllFragments() {
@@ -1295,6 +1325,7 @@ public final class BuildConfiguration {
     globalMakeEnv = globalMakeEnvBuilder.build();
 
     checksum = Fingerprint.md5Digest(buildOptions.computeCacheKey());
+    hashCode = computeHashCode();
   }
 
   /**
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/util/BuildViewTestCase.java b/src/test/java/com/google/devtools/build/lib/analysis/util/BuildViewTestCase.java
index 9cf952c200..d9dd9ae4ae 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/util/BuildViewTestCase.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/util/BuildViewTestCase.java
@@ -426,7 +426,7 @@ public abstract class BuildViewTestCase extends FoundationTestCase {
    */
   protected final void createBuildView() throws Exception {
     Preconditions.checkNotNull(masterConfig);
-    Preconditions.checkState(getHostConfiguration() == getTargetConfiguration()
+    Preconditions.checkState(getHostConfiguration().equals(getTargetConfiguration())
         || getHostConfiguration().isHostConfiguration(),
         "Host configuration %s is not a host configuration' "
         + "and does not match target configuration %s",