Check dereference of qualifier expression in method reference (#920)

Fixes #919
uber · Feb 23, 2024 · a7bb7d3 · a7bb7d3
1 parent 3a3d8e7
commit a7bb7d3
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diff --git a/nullaway/src/main/java/com/uber/nullaway/NullAway.java b/nullaway/src/main/java/com/uber/nullaway/NullAway.java
@@ -986,6 +986,14 @@ public Description matchMemberReference(MemberReferenceTree tree, VisitorState s
     if (!withinAnnotatedCode(state)) {
       return Description.NO_MATCH;
     }
+    // Technically the qualifier expression of a method reference gets passed to
+    // Objects.requireNonNull, but it's fine to treat it as a dereference for error-checking
+    // purposes.  The error message will be slightly inaccurate
+    Description derefErrorDescription =
+        matchDereference(tree.getQualifierExpression(), tree, state);
+    if (derefErrorDescription != Description.NO_MATCH) {
+      state.reportMatch(derefErrorDescription);
+    }
     Symbol.MethodSymbol referencedMethod = ASTHelpers.getSymbol(tree);
     Symbol.MethodSymbol funcInterfaceSymbol =
         NullabilityUtil.getFunctionalInterfaceMethod(tree, state.getTypes());

diff --git a/nullaway/src/test/java/com/uber/nullaway/NullAwayJava8Tests.java b/nullaway/src/test/java/com/uber/nullaway/NullAwayJava8Tests.java
@@ -22,4 +22,20 @@ public void functionalMethodSuperInterface() {
   public void functionalMethodOverrideSuperInterface() {
     defaultCompilationHelper.addSourceFile("NullAwayOverrideFunctionalInterfaces.java").doTest();
   }
+
+  @Test
+  public void methodReferenceOnNullableVariable() {
+    defaultCompilationHelper
+        .addSourceLines(
+            "Test.java",
+            "package com.uber;",
+            "import org.jspecify.annotations.Nullable;",
+            "class Test {",
+            "  public static boolean test(@Nullable String text, java.util.Set<String> s) {",
+            "    // BUG: Diagnostic contains: dereferenced expression text is @Nullable",
+            "    return s.stream().anyMatch(text::contains);",
+            "  }",
+            "}")
+        .doTest();
+  }
 }