fix explicitly-typed lambdas

uber · Oct 10, 2024 · 25ad62a · 25ad62a
1 parent 9dcac6b
commit 25ad62a
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Showing 2 changed files with 31 additions and 2 deletions.
diff --git a/nullaway/src/main/java/com/uber/nullaway/NullabilityUtil.java b/nullaway/src/main/java/com/uber/nullaway/NullabilityUtil.java
@@ -308,6 +308,7 @@ public static Stream<? extends AnnotationMirror> getTypeUseAnnotations(
     Symbol typeAnnotationOwner;
     switch (symbol.getKind()) {
       case PARAMETER:
+        // use the symbol's owner for parameters, unless it's the parameter of a lambda
         typeAnnotationOwner = symbol.owner;
         break;
       default:
@@ -344,8 +345,16 @@ private static boolean targetTypeMatches(Symbol sym, TypeAnnotationPosition posi
       case PARAMETER:
         switch (position.type) {
           case METHOD_FORMAL_PARAMETER:
-            return ((Symbol.MethodSymbol) sym.owner).getParameters().indexOf(sym)
-                == position.parameter_index;
+            int parameterIndex = position.parameter_index;
+            if (position.onLambda != null) {
+              com.sun.tools.javac.util.List<JCTree.JCVariableDecl> lambdaParams =
+                  position.onLambda.params;
+              return parameterIndex < lambdaParams.size()
+                  && lambdaParams.get(parameterIndex).sym.equals(sym);
+            } else {
+              return ((Symbol.MethodSymbol) sym.owner).getParameters().indexOf(sym)
+                  == parameterIndex;
+            }
           default:
             return false;
         }

diff --git a/nullaway/src/test/java/com/uber/nullaway/Java8Tests.java b/nullaway/src/test/java/com/uber/nullaway/Java8Tests.java
@@ -47,4 +47,24 @@ public void methodReferenceOnNullableVariable() {
             "}")
         .doTest();
   }
+
+  @Test
+  public void testNullableLambdaParamTypeUse() {
+    defaultCompilationHelper
+        .addSourceLines(
+            "Test.java",
+            "package com.uber;",
+            "import org.jspecify.annotations.Nullable;",
+            "class Test {",
+            "    @FunctionalInterface",
+            "    interface NullableParamFunctionTypeUse<T, U> {",
+            "      U takeVal(@org.jspecify.annotations.Nullable T x);",
+            "    }",
+            "    static void testParamTypeUse() {",
+            "      NullableParamFunctionTypeUse n3 = (@org.jspecify.annotations.Nullable Object x) -> (x == null) ? \"null\" : x.toString();",
+            "      NullableParamFunctionTypeUse n4 = (x) -> (x == null) ? \"null\" : x.toString();",
+            "    }",
+            "}")
+        .doTest();
+  }
 }