From 6d623927c336dc6178021748b56def10da321265 Mon Sep 17 00:00:00 2001
From: Manu Sridharan <msridhar@gmail.com>
Date: Tue, 26 Nov 2024 15:42:56 -0800
Subject: [PATCH] Some tweaks to `@Initializer` annotations in wala.util
 (#1474)

- Remove a couple of `@Nullable` annotations and add `@Initializer`
instead, to better capture the protocol.
- Remove WALA's custom `@Initializer` annotation and use the one from
NullAway's annotations package, which we already depend on.
---
 .../java/com/ibm/wala/qual/Initializer.java   | 24 -------------------
 .../traverse/DFSDiscoverTimeIterator.java     |  4 +++-
 .../graph/traverse/DFSFinishTimeIterator.java |  2 +-
 .../GraphDFSDiscoverTimeIterator.java         |  7 +++---
 4 files changed, 7 insertions(+), 30 deletions(-)
 delete mode 100644 util/src/main/java/com/ibm/wala/qual/Initializer.java

diff --git a/util/src/main/java/com/ibm/wala/qual/Initializer.java b/util/src/main/java/com/ibm/wala/qual/Initializer.java
deleted file mode 100644
index 1cb43e3734..0000000000
--- a/util/src/main/java/com/ibm/wala/qual/Initializer.java
+++ /dev/null
@@ -1,24 +0,0 @@
-/*
- * Copyright (c) 2002 - 2022 IBM Corporation.
- * All rights reserved. This program and the accompanying materials
- * are made available under the terms of the Eclipse Public License v1.0
- * which accompanies this distribution, and is available at
- * http://www.eclipse.org/legal/epl-v10.html
- *
- * Contributors:
- *     IBM Corporation - initial API and implementation
- */
-
-package com.ibm.wala.qual;
-
-import java.lang.annotation.ElementType;
-import java.lang.annotation.Retention;
-import java.lang.annotation.RetentionPolicy;
-import java.lang.annotation.Target;
-
-/**
- * A method annotated with @Initializer is expected to always be invoked before the object is used.
- */
-@Retention(RetentionPolicy.CLASS)
-@Target({ElementType.TYPE, ElementType.FIELD, ElementType.CONSTRUCTOR, ElementType.METHOD})
-public @interface Initializer {}
diff --git a/util/src/main/java/com/ibm/wala/util/graph/traverse/DFSDiscoverTimeIterator.java b/util/src/main/java/com/ibm/wala/util/graph/traverse/DFSDiscoverTimeIterator.java
index d17e42f65e..704aeb6d53 100644
--- a/util/src/main/java/com/ibm/wala/util/graph/traverse/DFSDiscoverTimeIterator.java
+++ b/util/src/main/java/com/ibm/wala/util/graph/traverse/DFSDiscoverTimeIterator.java
@@ -15,6 +15,7 @@
 import com.ibm.wala.util.collections.NonNullSingletonIterator;
 import com.ibm.wala.util.debug.UnimplementedError;
 import com.ibm.wala.util.graph.NumberedGraph;
+import com.uber.nullaway.annotations.Initializer;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
@@ -32,9 +33,10 @@ public abstract class DFSDiscoverTimeIterator<T> extends ArrayList<T> implements
   private static final long serialVersionUID = 4238700455408861924L;
 
   /** an enumeration of all nodes to search from */
-  private @Nullable Iterator<? extends T> roots;
+  private Iterator<? extends T> roots;
 
   /** subclass constructors must call this! */
+  @Initializer
   protected void init(Iterator<? extends T> nodes) {
     roots = nodes;
     assert nodes != null;
diff --git a/util/src/main/java/com/ibm/wala/util/graph/traverse/DFSFinishTimeIterator.java b/util/src/main/java/com/ibm/wala/util/graph/traverse/DFSFinishTimeIterator.java
index 431ab8994d..e8e89730fb 100644
--- a/util/src/main/java/com/ibm/wala/util/graph/traverse/DFSFinishTimeIterator.java
+++ b/util/src/main/java/com/ibm/wala/util/graph/traverse/DFSFinishTimeIterator.java
@@ -10,11 +10,11 @@
  */
 package com.ibm.wala.util.graph.traverse;
 
-import com.ibm.wala.qual.Initializer;
 import com.ibm.wala.util.collections.EmptyIterator;
 import com.ibm.wala.util.collections.Iterator2Iterable;
 import com.ibm.wala.util.debug.UnimplementedError;
 import com.ibm.wala.util.graph.Graph;
+import com.uber.nullaway.annotations.Initializer;
 import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.NoSuchElementException;
diff --git a/util/src/main/java/com/ibm/wala/util/graph/traverse/GraphDFSDiscoverTimeIterator.java b/util/src/main/java/com/ibm/wala/util/graph/traverse/GraphDFSDiscoverTimeIterator.java
index df05cf0c17..5c094328f6 100644
--- a/util/src/main/java/com/ibm/wala/util/graph/traverse/GraphDFSDiscoverTimeIterator.java
+++ b/util/src/main/java/com/ibm/wala/util/graph/traverse/GraphDFSDiscoverTimeIterator.java
@@ -11,17 +11,17 @@
 package com.ibm.wala.util.graph.traverse;
 
 import com.ibm.wala.util.graph.Graph;
+import com.uber.nullaway.annotations.Initializer;
 import java.util.Iterator;
-import org.jspecify.annotations.NullUnmarked;
-import org.jspecify.annotations.Nullable;
 
 abstract class GraphDFSDiscoverTimeIterator<T> extends DFSDiscoverTimeIterator<T> {
 
   private static final long serialVersionUID = -5673397879499010863L;
 
   /** the graph being searched */
-  private @Nullable Graph<T> G;
+  private Graph<T> G;
 
+  @Initializer
   protected void init(Graph<T> G, Iterator<? extends T> nodes) {
     if (G == null) {
       throw new IllegalArgumentException("G is null");
@@ -30,7 +30,6 @@ protected void init(Graph<T> G, Iterator<? extends T> nodes) {
     super.init(nodes);
   }
 
-  @NullUnmarked
   @Override
   protected Iterator<? extends T> getConnected(T n) {
     return G.getSuccNodes(n);