Include cause when reporting ActionExecutionException

`SkyframeActionExecutor#toActionExecutionException` claimed to combine the user-provided message and the exception's message when reporting an error, but did not.

This is fixed so that errors can be diagnosed directly from the build logs, without having to look into `java.log`.

Work towards bazelbuild#10363

Closes bazelbuild#18169.

PiperOrigin-RevId: 526195991
Change-Id: I978a6d739c37384121acccccf95e8dcb80ac5d25

src/main/java/com/google/devtools/build/lib/actions/ActionExecutionException.java

@@ -57,7 +57,7 @@ public ActionExecutionException(
       ActionAnalysisMetadata action,
       boolean catastrophe,
       DetailedExitCode detailedExitCode) {
-    super(message, cause);
+    super(combineMessages(message, cause), cause);
     this.action = action;
     this.catastrophe = catastrophe;
     this.detailedExitCode = checkNotNull(detailedExitCode);
@@ -96,7 +96,7 @@ public ActionExecutionException(
       NestedSet<Cause> rootCauses,
       boolean catastrophe,
       DetailedExitCode detailedExitCode) {
-    super(message, cause);
+    super(combineMessages(message, cause), cause);
     this.action = action;
     this.rootCauses = rootCauses;
     this.catastrophe = catastrophe;
@@ -203,4 +203,12 @@ public DetailedExitCode getDetailedExitCode() {
   public boolean showError() {
     return getMessage() != null;
   }
+
+  @Nullable
+  private static String combineMessages(String message, @Nullable Throwable cause) {
+    if (cause == null || cause.getMessage() == null) {
+      return message;
+    }
+    return message + ": " + cause.getMessage();
+  }
 }

src/test/java/com/google/devtools/build/lib/actions/ActionExecutionExceptionTest.java

@@ -0,0 +1,45 @@
+// 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.actions;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.devtools.build.lib.actions.util.ActionsTestUtil;
+import com.google.devtools.build.lib.actions.util.TestAction.DummyAction;
+import com.google.devtools.build.lib.server.FailureDetails.Execution;
+import com.google.devtools.build.lib.server.FailureDetails.FailureDetail;
+import com.google.devtools.build.lib.util.DetailedExitCode;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** {@link ActionExecutionException}Test */
+@RunWith(JUnit4.class)
+public final class ActionExecutionExceptionTest {
+
+  @Test
+  public void containsCauseMessage() {
+    Exception e =
+        new ActionExecutionException(
+            "message",
+            new Exception("cause"),
+            new DummyAction(ActionsTestUtil.DUMMY_ARTIFACT, ActionsTestUtil.DUMMY_ARTIFACT),
+            false,
+            DetailedExitCode.of(
+                FailureDetail.newBuilder().setExecution(Execution.getDefaultInstance()).build()));
+    assertThat(e).hasMessageThat().contains("message");
+    assertThat(e).hasMessageThat().contains("cause");
+  }
+}

src/test/java/com/google/devtools/build/lib/actions/BUILD

@@ -64,6 +64,7 @@ java_library(
         "//src/main/java/com/google/devtools/build/lib/skyframe/serialization/testutils",
         "//src/main/java/com/google/devtools/build/lib/skyframe/serialization/testutils:depsutils",
         "//src/main/java/com/google/devtools/build/lib/util",
+        "//src/main/java/com/google/devtools/build/lib/util:detailed_exit_code",
         "//src/main/java/com/google/devtools/build/lib/util:filetype",
         "//src/main/java/com/google/devtools/build/lib/util:string",
         "//src/main/java/com/google/devtools/build/lib/vfs",