Type-check tests for @GroupedList.Compressed.

Each test enforces that all objects referenced by @GroupedList.Compressed in the package originate from one of the annotated static methods in GroupedList.

To be submitted after #8212.

PiperOrigin-RevId: 246052739

src/main/java/com/google/devtools/build/lib/BUILD

@@ -261,6 +261,7 @@ java_library(
         "//src/main/java/com/google/devtools/build/lib/vfs",
         "//src/main/java/com/google/devtools/common/options",
         "//third_party:apache_commons_lang",
+        "//third_party:checker_framework_annotations",
         "//third_party:error_prone_annotations",
         "//third_party:guava",
         "//third_party:jsr305",

src/main/java/com/google/devtools/build/lib/util/GroupedList.java

@@ -28,6 +28,10 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Set;
+import org.checkerframework.framework.qual.DefaultQualifierInHierarchy;
+import org.checkerframework.framework.qual.ImplicitFor;
+import org.checkerframework.framework.qual.LiteralKind;
+import org.checkerframework.framework.qual.SubtypeOf;
 
 /**
  * Encapsulates a list of groups. Is intended to be used in "batch" mode -- to set the value of a
@@ -47,15 +51,17 @@ public class GroupedList<T> implements Iterable<List<T>> {
    * Indicates that the annotated element is a compressed {@link GroupedList}, so that it can be
    * safely passed to {@link #create} and friends.
    */
-  // TODO(jhorvitz): enforce this annotation via compile-time checks.
-  @Target({
-    ElementType.PARAMETER,
-    ElementType.FIELD,
-    ElementType.LOCAL_VARIABLE,
-    ElementType.TYPE_USE
-  })
+  @SubtypeOf(DefaultObject.class)
+  @Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER})
+  @ImplicitFor(literals = LiteralKind.NULL)
   public @interface Compressed {}
 
+  /** Default annotation for type-safety checks of {@link Compressed}. */
+  @DefaultQualifierInHierarchy
+  @SubtypeOf({})
+  @Target({ElementType.TYPE_USE, ElementType.TYPE_PARAMETER})
+  private @interface DefaultObject {}
+
   // Total number of items in the list. At least elements.size(), but might be larger if there are
   // any nested lists.
   private int size = 0;
@@ -222,7 +228,7 @@ public int numElements() {
     return size;
   }
 
-  public static int numElements(Object compressed) {
+  public static int numElements(@Compressed Object compressed) {
     if (compressed == EMPTY_LIST) {
       return 0;
     }
@@ -264,6 +270,16 @@ public static <T> Iterable<T> compressedToIterable(@Compressed Object compressed
     return ImmutableList.of((T) compressed);
   }
 
+  /**
+   * Casts an {@code Object} which is known to be {@link Compressed}.
+   *
+   * <p>This method should only be used when it is not possible to enforce the type via annotations.
+   */
+  public static @Compressed Object castAsCompressed(Object obj) {
+    Preconditions.checkArgument(!(obj instanceof GroupedList), obj);
+    return (@Compressed Object) obj;
+  }
+
   /** Returns true if this list contains no elements. */
   public boolean isEmpty() {
     return elements.isEmpty();
@@ -334,7 +350,7 @@ public static <E> GroupedList<E> create(@Compressed Object compressed) {
   }
 
   /** Creates an already compressed {@code GroupedList} for storage. */
-  public static <E> @Compressed Object createCompressedWithTwoGroupes(
+  public static <E> @Compressed Object createCompressedWithTwoGroups(
       E singletonElementOfFirstGroup, List<? extends E> elementsOfSecondGroup) {
     switch (elementsOfSecondGroup.size()) {
       case 0:
@@ -441,10 +457,7 @@ public boolean equals(Object other) {
 
   @Override
   public String toString() {
-    return MoreObjects.toStringHelper(this)
-        .add("elements", elements)
-        .add("size", size).toString();
-
+    return MoreObjects.toStringHelper(this).add("elements", elements).add("size", size).toString();
   }
 
   /**
@@ -591,7 +604,8 @@ public String toString() {
       return MoreObjects.toStringHelper(this)
           .add("groupedList", groupedList)
           .add("elements", elements)
-          .add("currentGroup", currentGroup).toString();
+          .add("currentGroup", currentGroup)
+          .toString();
     }
   }
 }

src/main/java/com/google/devtools/build/skyframe/InMemoryNodeEntry.java

@@ -138,11 +138,8 @@ public class InMemoryNodeEntry implements NodeEntry {
    */
   @Nullable protected volatile DirtyBuildingState dirtyBuildingState = null;
 
-  /**
-   * Construct a InMemoryNodeEntry. Use ONLY in Skyframe evaluation and graph implementations.
-   */
-  public InMemoryNodeEntry() {
-  }
+  /** Construct a InMemoryNodeEntry. Use ONLY in Skyframe evaluation and graph implementations. */
+  public InMemoryNodeEntry() {}
 
   // Public only for use in alternate graph implementations.
   public KeepEdgesPolicy keepEdges() {
@@ -218,12 +215,12 @@ public synchronized Iterable<SkyKey> getDirectDeps() {
   public synchronized @GroupedList.Compressed Object getCompressedDirectDepsForDoneEntry() {
     assertKeepDeps();
     Preconditions.checkState(isDone(), "no deps until done. NodeEntry: %s", this);
-    return Preconditions.checkNotNull(directDeps, "deps can't be null: %s", this);
+    Preconditions.checkNotNull(directDeps, "deps can't be null: %s", this);
+    return GroupedList.castAsCompressed(directDeps);
   }
 
   public int getNumDirectDeps() {
-    Preconditions.checkState(isDone(), "no deps until done. NodeEntry: %s", this);
-    return GroupedList.numElements(directDeps);
+    return GroupedList.numElements(getCompressedDirectDepsForDoneEntry());
   }
 
   @Override
@@ -520,7 +517,8 @@ public synchronized MarkedDirtyResult markDirty(DirtyType dirtyType) {
     assertKeepDeps();
     if (isDone()) {
       dirtyBuildingState =
-          DirtyBuildingState.create(dirtyType, GroupedList.create(directDeps), value);
+          DirtyBuildingState.create(
+              dirtyType, GroupedList.create(getCompressedDirectDepsForDoneEntry()), value);
       value = null;
       directDeps = null;
       return new MarkedDirtyResult(ReverseDepsUtility.getReverseDeps(this));
@@ -733,7 +731,7 @@ protected synchronized MoreObjects.ToStringHelper toStringHelper() {
         .add(
             "directDeps",
             isDone() && keepEdges() != KeepEdgesPolicy.NONE
-                ? GroupedList.create(directDeps)
+                ? GroupedList.create(getCompressedDirectDepsForDoneEntry())
                 : directDeps)
         .add("reverseDeps", ReverseDepsUtility.toString(this))
         .add("dirtyBuildingState", dirtyBuildingState);

src/test/java/com/google/devtools/build/lib/util/GroupedListTest.java

@@ -215,10 +215,10 @@ public void createCompressed() {
     GroupedList<String> groupedList = new GroupedList<>();
     groupedList.appendGroup(ImmutableList.of("a"));
     groupedList.appendGroup(ImmutableList.of("b", "c"));
-    assertThat(GroupedList.createCompressedWithTwoGroupes("a", ImmutableList.of("b", "c")))
+    assertThat(GroupedList.createCompressedWithTwoGroups("a", ImmutableList.of("b", "c")))
         .isEqualTo(groupedList.compress());
     groupedList.remove(ImmutableSet.of("b"));
-    assertThat(GroupedList.createCompressedWithTwoGroupes("a", ImmutableList.of("c")))
+    assertThat(GroupedList.createCompressedWithTwoGroups("a", ImmutableList.of("c")))
         .isEqualTo(groupedList.compress());
   }