From 036078136a64a487e400e0ef77038568534e082b Mon Sep 17 00:00:00 2001
From: Werner Dietl <wdietl@gmail.com>
Date: Sun, 26 Nov 2023 18:10:46 -0500
Subject: [PATCH 1/2] Do not use `thisValue` when it is the NullType

---
 .../initialization/InitializationStore.java   |  4 +++-
 .../EisopIssue635.java                        | 22 +++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 checker/tests/nullness-initialization/EisopIssue635.java

diff --git a/checker/src/main/java/org/checkerframework/checker/initialization/InitializationStore.java b/checker/src/main/java/org/checkerframework/checker/initialization/InitializationStore.java
index a40ceb3aba0..34b60a09ad0 100644
--- a/checker/src/main/java/org/checkerframework/checker/initialization/InitializationStore.java
+++ b/checker/src/main/java/org/checkerframework/checker/initialization/InitializationStore.java
@@ -158,7 +158,9 @@ protected boolean isDeclaredInitialized(FieldAccess fieldAccess) {
         InitializationParentAnnotatedTypeFactory atypeFactory =
                 (InitializationParentAnnotatedTypeFactory) analysis.getTypeFactory();
         AnnotatedTypeMirror receiverType;
-        if (thisValue != null && thisValue.getUnderlyingType().getKind() != TypeKind.ERROR) {
+        if (thisValue != null
+                && thisValue.getUnderlyingType().getKind() != TypeKind.ERROR
+                && thisValue.getUnderlyingType().getKind() != TypeKind.NULL) {
             receiverType =
                     AnnotatedTypeMirror.createType(
                             thisValue.getUnderlyingType(), atypeFactory, false);
diff --git a/checker/tests/nullness-initialization/EisopIssue635.java b/checker/tests/nullness-initialization/EisopIssue635.java
new file mode 100644
index 00000000000..d8416628d57
--- /dev/null
+++ b/checker/tests/nullness-initialization/EisopIssue635.java
@@ -0,0 +1,22 @@
+import org.checkerframework.checker.nullness.qual.Nullable;
+
+class EisopIssue635 {
+
+    private @Nullable Runnable r;
+
+    private void f() {
+        // No crash without this assignment first.
+        r = null;
+        r =
+                new Runnable() {
+                    @Override
+                    public void run() {
+                        if (r != this) {
+                            return;
+                        }
+                        // No crash without this call.
+                        f();
+                    }
+                };
+    }
+}

From a87a950e9a285bafea23053941b3411a1d005ab1 Mon Sep 17 00:00:00 2001
From: Werner Dietl <wdietl@gmail.com>
Date: Sun, 26 Nov 2023 18:18:05 -0500
Subject: [PATCH 2/2] Add changelog entry

---
 docs/CHANGELOG.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 2d71038049d..6e9f0d4a6a2 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -7,6 +7,8 @@ Version 3.40.0-eisop3 (November ??, 2023)
 
 **Closed issues:**
 
+eisop#635.
+
 
 Version 3.40.0-eisop2 (November 24, 2023)
 -----------------------------------------