Test reference equality before structural equality (eisop#1644)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: wmdietl

dataflow/src/main/java/org/checkerframework/dataflow/analysis/TransferInput.java

@@ -279,6 +279,9 @@ public TransferInput<V, S> leastUpperBound(TransferInput<V, S> other) {
 
     @Override
     public boolean equals(@Nullable Object o) {
+        if (this == o) {
+            return true;
+        }
         if (o instanceof TransferInput) {
             @SuppressWarnings("unchecked")
             TransferInput<V, S> other = (TransferInput<V, S>) o;

dataflow/src/main/java/org/checkerframework/dataflow/busyexpr/BusyExprStore.java

@@ -129,6 +129,9 @@ public String toString() {
 
     @Override
     public boolean equals(@Nullable Object obj) {
+        if (this == obj) {
+            return true;
+        }
         if (!(obj instanceof BusyExprStore)) {
             return false;
         }

dataflow/src/main/java/org/checkerframework/dataflow/busyexpr/BusyExprValue.java

@@ -39,6 +39,9 @@ public int hashCode() {
 
     @Override
     public boolean equals(@Nullable Object obj) {
+        if (this == obj) {
+            return true;
+        }
         if (!(obj instanceof BusyExprValue)) {
             return false;
         }

dataflow/src/main/java/org/checkerframework/dataflow/cfg/node/ArrayAccessNode.java

@@ -138,6 +138,9 @@ public String toString() {
 
     @Override
     public boolean equals(@Nullable Object obj) {
+        if (this == obj) {
+            return true;
+        }
         if (!(obj instanceof ArrayAccessNode)) {
             return false;
         }

dataflow/src/main/java/org/checkerframework/dataflow/cfg/node/ArrayCreationNode.java

@@ -92,6 +92,9 @@ public String toString() {
 
     @Override
     public boolean equals(@Nullable Object obj) {
+        if (this == obj) {
+            return true;
+        }
         if (!(obj instanceof ArrayCreationNode)) {
             return false;
         }

dataflow/src/main/java/org/checkerframework/dataflow/cfg/node/ArrayTypeNode.java

@@ -48,6 +48,9 @@ public String toString() {
 
     @Override
     public boolean equals(@Nullable Object obj) {
+        if (this == obj) {
+            return true;
+        }
         if (!(obj instanceof ArrayTypeNode)) {
             return false;
         }

dataflow/src/main/java/org/checkerframework/dataflow/cfg/node/AssertionErrorNode.java

@@ -86,6 +86,9 @@ public String toString() {
 
     @Override
     public boolean equals(@Nullable Object obj) {
+        if (this == obj) {
+            return true;
+        }
         if (!(obj instanceof AssertionErrorNode)) {
             return false;
         }

dataflow/src/main/java/org/checkerframework/dataflow/cfg/node/AssignmentNode.java

@@ -155,6 +155,9 @@ public String toString() {
     @Override
     @Pure
     public boolean equals(@Nullable Object obj) {
+        if (this == obj) {
+            return true;
+        }
         if (!(obj instanceof AssignmentNode)) {
             return false;
         }

dataflow/src/main/java/org/checkerframework/dataflow/cfg/node/BitwiseAndNode.java

@@ -40,6 +40,9 @@ public String toString() {
 
     @Override
     public boolean equals(@Nullable Object obj) {
+        if (this == obj) {
+            return true;
+        }
         if (!(obj instanceof BitwiseAndNode)) {
             return false;
         }

dataflow/src/main/java/org/checkerframework/dataflow/cfg/node/BitwiseComplementNode.java

@@ -39,6 +39,9 @@ public String toString() {
 
     @Override
     public boolean equals(@Nullable Object obj) {
+        if (this == obj) {
+            return true;
+        }
         if (!(obj instanceof BitwiseComplementNode)) {
             return false;
         }