From 3f5867aac144898c29e809562ed1888abd6839d6 Mon Sep 17 00:00:00 2001
From: Stephan Schroevers <stephan.schroevers@teampicnic.com>
Date: Tue, 16 Jan 2024 09:12:34 +0100
Subject: [PATCH] Avoid NPE in `IsEmpty` matcher

---
 .../errorprone/refaster/matchers/IsEmpty.java |  3 +-
 .../refaster/matchers/IsEmptyTest.java        | 41 +++++++++++--------
 2 files changed, 25 insertions(+), 19 deletions(-)

diff --git a/refaster-support/src/main/java/tech/picnic/errorprone/refaster/matchers/IsEmpty.java b/refaster-support/src/main/java/tech/picnic/errorprone/refaster/matchers/IsEmpty.java
index fb0c77b748..fd44397a57 100644
--- a/refaster-support/src/main/java/tech/picnic/errorprone/refaster/matchers/IsEmpty.java
+++ b/refaster-support/src/main/java/tech/picnic/errorprone/refaster/matchers/IsEmpty.java
@@ -56,6 +56,7 @@
 // XXX: Also recognize empty builders and `emptyBuilder.build()` invocations.
 public final class IsEmpty implements Matcher<ExpressionTree> {
   private static final long serialVersionUID = 1L;
+  private static final Integer ZERO = 0;
   private static final Pattern EMPTY_INSTANCE_FACTORY_METHOD_PATTERN = Pattern.compile("empty.*");
   private static final Matcher<Tree> EMPTY_COLLECTION_CONSTRUCTOR_ARGUMENT =
       anyOf(isPrimitiveType(), isSubtypeOf(Comparator.class));
@@ -145,7 +146,7 @@ private static boolean isEmptyArrayCreation(ExpressionTree tree) {
 
     NewArrayTree newArray = (NewArrayTree) tree;
     return (!newArray.getDimensions().isEmpty()
-            && ASTHelpers.constValue(newArray.getDimensions().get(0), Integer.class) == 0)
+            && ZERO.equals(ASTHelpers.constValue(newArray.getDimensions().get(0), Integer.class)))
         || (newArray.getInitializers() != null && newArray.getInitializers().isEmpty());
   }
 }
diff --git a/refaster-support/src/test/java/tech/picnic/errorprone/refaster/matchers/IsEmptyTest.java b/refaster-support/src/test/java/tech/picnic/errorprone/refaster/matchers/IsEmptyTest.java
index 318328cbec..42656cab6a 100644
--- a/refaster-support/src/test/java/tech/picnic/errorprone/refaster/matchers/IsEmptyTest.java
+++ b/refaster-support/src/test/java/tech/picnic/errorprone/refaster/matchers/IsEmptyTest.java
@@ -55,75 +55,80 @@ void matches() {
             "    return new int[][] {{0}};",
             "  }",
             "",
-            "  Random negative5() {",
+            "  int[] negative5() {",
+            "    int i = hashCode();",
+            "    return new int[i];",
+            "  }",
+            "",
+            "  Random negative6() {",
             "    return new Random();",
             "  }",
             "",
-            "  List<Integer> negative6() {",
+            "  List<Integer> negative7() {",
             "    return new ArrayList<>(ImmutableList.of(1));",
             "  }",
             "",
-            "  Map<Integer, Integer> negative7() {",
+            "  Map<Integer, Integer> negative8() {",
             "    return new HashMap<>(ImmutableMap.of(1, 2));",
             "  }",
             "",
-            "  Set<Integer> negative8() {",
+            "  Set<Integer> negative9() {",
             "    return new HashSet<>(ImmutableList.of(1));",
             "  }",
             "",
-            "  Map<Integer, Integer> negative9() {",
+            "  Map<Integer, Integer> negative10() {",
             "    return new LinkedHashMap<>(ImmutableMap.of(1, 2));",
             "  }",
             "",
-            "  Set<Integer> negative10() {",
+            "  Set<Integer> negative11() {",
             "    return new LinkedHashSet<>(ImmutableList.of(1));",
             "  }",
             "",
-            "  List<Integer> negative11() {",
+            "  List<Integer> negative12() {",
             "    return new LinkedList<>(ImmutableList.of(1));",
             "  }",
             "",
-            "  Map<Integer, Integer> negative12() {",
+            "  Map<Integer, Integer> negative13() {",
             "    return new HashMap<>(ImmutableMap.of(1, 2));",
             "  }",
             "",
-            "  Set<Integer> negative13() {",
+            "  Set<Integer> negative14() {",
             "    return new HashSet<>(ImmutableList.of(1));",
             "  }",
             "",
-            "  List<Integer> negative14() {",
+            "  List<Integer> negative15() {",
             "    return new Vector<>(ImmutableList.of(1));",
             "  }",
             "",
-            "  ImmutableList<Integer> negative15() {",
+            "  ImmutableList<Integer> negative16() {",
             "    return ImmutableList.of(1);",
             "  }",
             "",
-            "  ImmutableSet<Integer> negative16() {",
+            "  ImmutableSet<Integer> negative17() {",
             "    return ImmutableSet.of(1);",
             "  }",
             "",
-            "  ImmutableMap<Integer, Integer> negative17() {",
+            "  ImmutableMap<Integer, Integer> negative18() {",
             "    return ImmutableMap.of(1, 2);",
             "  }",
             "",
-            "  ImmutableSetMultimap<Integer, Integer> negative18() {",
+            "  ImmutableSetMultimap<Integer, Integer> negative19() {",
             "    return ImmutableSetMultimap.of(1, 2);",
             "  }",
             "",
-            "  List<Integer> negative19() {",
+            "  List<Integer> negative20() {",
             "    return List.of(1);",
             "  }",
             "",
-            "  Map<Integer, Integer> negative20() {",
+            "  Map<Integer, Integer> negative21() {",
             "    return Map.of(1, 2);",
             "  }",
             "",
-            "  Set<Integer> negative21() {",
+            "  Set<Integer> negative22() {",
             "    return Set.of(1);",
             "  }",
             "",
-            "  Stream<Integer> negative22() {",
+            "  Stream<Integer> negative23() {",
             "    return Stream.of(1);",
             "  }",
             "",