Thread new incompatible flag into creation of execution transitions d…

…uring rule creation.

Part of work on execution transitions, bazelbuild#7935.

PiperOrigin-RevId: 257036118

src/main/java/com/google/devtools/build/lib/analysis/ConfiguredRuleClassProvider.java

@@ -269,6 +269,7 @@ public static class Builder implements RuleDefinitionEnvironment {
 
     private ThirdPartyLicenseExistencePolicy thirdPartyLicenseExistencePolicy =
         ThirdPartyLicenseExistencePolicy.USER_CONTROLLABLE;
+    private boolean enableExecutionTransition = false;
 
     public Builder addWorkspaceFilePrefix(String contents) {
       defaultWorkspaceFilePrefix.append(contents);
@@ -456,6 +457,16 @@ public Builder setShouldInvalidateCacheForOptionDiff(
       return this;
     }
 
+    @Override
+    public boolean enableExecutionTransition() {
+      return enableExecutionTransition;
+    }
+
+    public Builder enableExecutionTransition(boolean flag) {
+      this.enableExecutionTransition = flag;
+      return this;
+    }
+
     /**
      * Overrides the predicate which determines whether the analysis cache should be invalidated for
      * the given options diff.

src/main/java/com/google/devtools/build/lib/analysis/RuleDefinitionEnvironment.java

@@ -31,4 +31,7 @@ public interface RuleDefinitionEnvironment {
    * Returns the tools repository prefix.
    */
   String getToolsRepository();
+
+  /** Returns whether the execution transition should be enabled. */
+  boolean enableExecutionTransition();
 }

src/main/java/com/google/devtools/build/lib/analysis/config/ExecutionTransitionFactory.java

@@ -30,6 +30,19 @@
  */
 public class ExecutionTransitionFactory implements TransitionFactory<AttributeTransitionData> {
 
+  /**
+   * Returns either a new {@link ExecutionTransitionFactory} or a factory for the {@link
+   * HostTransition}, depending on the value of {@code enableExecutionTransition}.
+   */
+  public static TransitionFactory<AttributeTransitionData> create(
+      boolean enableExecutionTransition) {
+    if (enableExecutionTransition) {
+      return new ExecutionTransitionFactory();
+    } else {
+      return HostTransition.createFactory();
+    }
+  }
+
   @Override
   public PatchTransition create(AttributeTransitionData data) {
     return new ExecutionTransition(data.executionPlatform());

src/main/java/com/google/devtools/build/lib/runtime/BlazeRuntime.java

@@ -1488,6 +1488,12 @@ public BlazeRuntime build() throws AbruptExitException {
 
       ConfiguredRuleClassProvider.Builder ruleClassBuilder =
           new ConfiguredRuleClassProvider.Builder();
+      BlazeServerStartupOptions blazeServerStartupOptions =
+          startupOptionsProvider.getOptions(BlazeServerStartupOptions.class);
+      if (blazeServerStartupOptions != null) {
+        ruleClassBuilder.enableExecutionTransition(
+            blazeServerStartupOptions.enableExecutionTransition);
+      }
       for (BlazeModule module : blazeModules) {
         module.initializeRuleClasses(ruleClassBuilder);
       }