Fix handling of references to methods of array types and type variabl…

…es (#926) After #920 we check the nullability of the qualifier expression of a method reference. We weren't correctly handling the cases where that expression was an array type or a type variable
uber · Mar 4, 2024 · 348bb4d · 348bb4d
1 parent d7c757f
commit 348bb4d
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Showing 2 changed files with 13 additions and 3 deletions.
diff --git a/nullaway/src/main/java/com/uber/nullaway/NullAway.java b/nullaway/src/main/java/com/uber/nullaway/NullAway.java
@@ -2326,7 +2326,7 @@ private boolean mayBeNullExpr(VisitorState state, ExpressionTree expr) {
         return true;
       case NEW_CLASS:
       case NEW_ARRAY:
-        // for string concatenation, auto-boxing
+      case ARRAY_TYPE:
       case LAMBDA_EXPRESSION:
         // Lambdas may return null, but the lambda literal itself should not be null
       case MEMBER_REFERENCE:
@@ -2485,7 +2485,8 @@ private Description matchDereference(
     if (baseExpressionSymbol != null) {
       if (baseExpressionSymbol.type.isPrimitive()
           || baseExpressionSymbol.getKind() == ElementKind.PACKAGE
-          || ElementUtils.isTypeElement(baseExpressionSymbol)) {
+          || ElementUtils.isTypeElement(baseExpressionSymbol)
+          || baseExpressionSymbol.getKind() == ElementKind.TYPE_PARAMETER) {
         // we know we don't have a null dereference here
         return Description.NO_MATCH;
       }

diff --git a/nullaway/src/test/java/com/uber/nullaway/NullAwayJava8Tests.java b/nullaway/src/test/java/com/uber/nullaway/NullAwayJava8Tests.java
@@ -30,11 +30,20 @@ public void methodReferenceOnNullableVariable() {
             "Test.java",
             "package com.uber;",
             "import org.jspecify.annotations.Nullable;",
+            "import java.util.Arrays;",
+            "import java.util.stream.Collectors;",
             "class Test {",
-            "  public static boolean test(@Nullable String text, java.util.Set<String> s) {",
+            "  public static boolean testPositive(@Nullable String text, java.util.Set<String> s) {",
             "    // BUG: Diagnostic contains: dereferenced expression text is @Nullable",
             "    return s.stream().anyMatch(text::contains);",
             "  }",
+            "  public static String[] testNegative(Object[] arr) {",
+            "    // also tests we don't crash when the qualifier expression of a method reference is a type",
+            "    return Arrays.stream(arr).map(Object::toString).toArray(String[]::new);",
+            "  }",
+            "  public static <T> boolean testNegativeWithTypeVariable(T[] arr) {",
+            "    return Arrays.stream(arr).map(T::toString).collect(Collectors.toList()).isEmpty();",
+            "  }",
             "}")
         .doTest();
   }