From e65e2ce730c3e5a6e2723ea87c8a7a5c144a607f Mon Sep 17 00:00:00 2001
From: Stephan Schroevers <stephan.schroevers@teampicnic.com>
Date: Sun, 28 Jan 2024 13:25:04 +0100
Subject: [PATCH] Prevent `ExplicitEnumOrdering` from throwing an NPE (#998)

---
 .../picnic/errorprone/bugpatterns/ExplicitEnumOrdering.java     | 2 +-
 .../picnic/errorprone/bugpatterns/ExplicitEnumOrderingTest.java | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ExplicitEnumOrdering.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ExplicitEnumOrdering.java
index 37fb7d6086..1320503146 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ExplicitEnumOrdering.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/ExplicitEnumOrdering.java
@@ -72,7 +72,7 @@ private static ImmutableSet<String> getMissingEnumValues(
       List<? extends ExpressionTree> expressions) {
     return expressions.stream()
         .map(ASTHelpers::getSymbol)
-        .filter(Symbol::isEnum)
+        .filter(s -> s != null && s.isEnum())
         .collect(
             collectingAndThen(
                 toImmutableSetMultimap(Symbol::asType, Symbol::toString),
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ExplicitEnumOrderingTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ExplicitEnumOrderingTest.java
index 7afdf30ac3..02f770ff94 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ExplicitEnumOrderingTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/ExplicitEnumOrderingTest.java
@@ -75,6 +75,8 @@ void identification() {
             "    Ordering.explicit(IsoEra.BCE, SOURCE, RetentionPolicy.CLASS);",
             "    // BUG: Diagnostic contains: RetentionPolicy.SOURCE, IsoEra.BCE",
             "    Ordering.explicit(CLASS, RUNTIME, CE);",
+            "",
+            "    Ordering.explicit(BCE, null, CE);",
             "  }",
             "}")
         .doTest();