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Fix wildcard inference bug with method references #1553

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Merged
msridhar merged 3 commits into from
May 3, 2026
+12 −2
Merged

Fix wildcard inference bug with method references #1553

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dc44d43
WIP
msridhar Apr 27, 2026
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msridhar Apr 27, 2026
f379612
improve test
msridhar May 3, 2026
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1 change: 1 addition & 0 deletions nullaway/src/main/java/com/uber/nullaway/generics/GenericsChecks.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1618,6 +1618,7 @@ public void compareGenericTypeParameterNullabilityForCall(
}
}
});
maybeStorePolyExpressionTypeFromTarget(currentActualParam, formalParameter);
return;
}

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13 changes: 11 additions & 2 deletions nullaway/src/test/java/com/uber/nullaway/jspecify/WildcardTests.java
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Expand Up @@ -537,15 +537,24 @@ interface Consumer<T extends @Nullable Object> {
static @Nullable String mapToNull(String s) {
return null;
}
static String id(String s) { return s; }
static void callHashCode(Object o) { o.hashCode(); }
static void test(List<String> list) {
static void doNothing(@Nullable Object o) {}
static void testPositive(List<String> list) {
list.stream().map(Test::mapToNull).forEach(s -> {
// BUG: Diagnostic contains: dereferenced expression s is @Nullable
s.hashCode();
});
// TODO we should report an error here (https://github.com/uber/NullAway/issues/1552)
// BUG: Diagnostic contains: parameter o of referenced method is @NonNull, but parameter in functional interface method Test.Consumer.accept(T) is @Nullable
list.stream().map(Test::mapToNull).forEach(Test::callHashCode);
}
static void testNegative(List<String> list) {
list.stream().map(Test::mapToNull).forEach(s -> {
if (s != null) { s.hashCode(); }
});
list.stream().map(Test::mapToNull).forEach(Test::doNothing);

@lazaroclapp lazaroclapp May 2, 2026

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Probably also worth checking that, without the map to null, a Stream<String> works just fine with .forEach(Test::callHashCode);, no?

list.stream().map(Test::id).forEach(Test::callHashCode);
}
}""")
.doTest();
}
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