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JSpecify: handle return types of method references in Java Generics #847

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merged 10 commits into from
Oct 19, 2023
Merged

JSpecify: handle return types of method references in Java Generics #847

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e73c18e
Adding test case and logic to handle return types of method reference…
akulk022 Oct 15, 2023
fbdd616
adding null check
akulk022 Oct 15, 2023
8c2f589
removing redundant lines
akulk022 Oct 15, 2023
150374b
Merge branch 'master' into generic_types_method_ref_return_abhijitk
akulk022 Oct 15, 2023
d92b71b
rewriting the ternary operator as if-else and adding comments for bet…
akulk022 Oct 17, 2023
17caf58
Merge remote-tracking branch 'origin/generic_types_method_ref_return_…
akulk022 Oct 17, 2023
dea0d60
dummy test commit
akulk022 Oct 18, 2023
b22da52
Adding test cases for different scenarios of generic type method refe…
akulk022 Oct 18, 2023
1096eaa
comment tweaks
msridhar Oct 19, 2023
56f95e3
Merge branch 'master' into generic_types_method_ref_return_abhijitk
msridhar Oct 19, 2023
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14 changes: 7 additions & 7 deletions nullaway/src/main/java/com/uber/nullaway/GenericsChecks.java
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Original file line number Diff line number Diff line change
Expand Up @@ -699,11 +699,6 @@ public static void checkTypeParameterNullnessForMethodOverriding(
public static Nullness getGenericMethodReturnTypeNullness(
Symbol.MethodSymbol method, Symbol enclosingSymbol, VisitorState state, Config config) {
Type enclosingType = getTypeForSymbol(enclosingSymbol, state);
if (enclosingType == null) {
// we have no additional information from generics, so return NONNULL (presence of a @Nullable
// annotation should have been handled by the caller)
return Nullness.NONNULL;
}
return getGenericMethodReturnTypeNullness(method, enclosingType, state, config);
}

Expand Down Expand Up @@ -735,8 +730,13 @@ private static Type getTypeForSymbol(Symbol symbol, VisitorState state) {
}
}

private static Nullness getGenericMethodReturnTypeNullness(
Symbol.MethodSymbol method, Type enclosingType, VisitorState state, Config config) {
static Nullness getGenericMethodReturnTypeNullness(
Symbol.MethodSymbol method, @Nullable Type enclosingType, VisitorState state, Config config) {
if (enclosingType == null) {
// we have no additional information from generics, so return NONNULL (presence of a @Nullable
// annotation should have been handled by the caller)
return Nullness.NONNULL;
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}
Type overriddenMethodType = state.getTypes().memberType(enclosingType, method);
verify(
overriddenMethodType instanceof ExecutableType,
Expand Down
19 changes: 14 additions & 5 deletions nullaway/src/main/java/com/uber/nullaway/NullAway.java
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Expand Up @@ -955,7 +955,8 @@ private Description checkOverriding(
// if the super method returns nonnull, overriding method better not return nullable
// Note that, for the overriding method, the permissive default is non-null,
// but it's nullable for the overridden one.
if (overriddenMethodReturnsNonNull(overriddenMethod, overridingMethod.owner, state)
if (overriddenMethodReturnsNonNull(
overriddenMethod, overridingMethod.owner, memberReferenceTree, state)
&& getMethodReturnNullness(overridingMethod, state, Nullness.NONNULL)
.equals(Nullness.NULLABLE)
&& (memberReferenceTree == null
Expand Down Expand Up @@ -994,7 +995,10 @@ && getMethodReturnNullness(overridingMethod, state, Nullness.NONNULL)
}

private boolean overriddenMethodReturnsNonNull(
Symbol.MethodSymbol overriddenMethod, Symbol enclosingSymbol, VisitorState state) {
Symbol.MethodSymbol overriddenMethod,
Symbol enclosingSymbol,
@Nullable MemberReferenceTree memberReferenceTree,
VisitorState state) {
Nullness methodReturnNullness =
getMethodReturnNullness(overriddenMethod, state, Nullness.NULLABLE);
if (!methodReturnNullness.equals(Nullness.NONNULL)) {
Expand All @@ -1003,9 +1007,14 @@ private boolean overriddenMethodReturnsNonNull(
// In JSpecify mode, for generic methods, we additionally need to check the return nullness
// using the type parameters from the type enclosing the overriding method
if (config.isJSpecifyMode()) {
return GenericsChecks.getGenericMethodReturnTypeNullness(
overriddenMethod, enclosingSymbol, state, config)
.equals(Nullness.NONNULL);

return (memberReferenceTree != null)
? GenericsChecks.getGenericMethodReturnTypeNullness(
overriddenMethod, ASTHelpers.getType(memberReferenceTree), state, config)
.equals(Nullness.NONNULL)
: GenericsChecks.getGenericMethodReturnTypeNullness(
overriddenMethod, enclosingSymbol, state, config)
.equals(Nullness.NONNULL);
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}
return true;
}
Expand Down
25 changes: 25 additions & 0 deletions nullaway/src/test/java/com/uber/nullaway/NullAwayJSpecifyGenericsTests.java
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Expand Up @@ -439,6 +439,31 @@ public void testForMethodReferenceInAnAssignment() {
.doTest();
}

@Test
public void testForMethodReferenceReturnType() {
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As noted in an offline discussion, this test looks good but let's add tests for more (pseudo-)assignments, like passing a method reference as a function parameter and returning a method reference

makeHelper()
.addSourceLines(
"Test.java",
"package com.uber;",
"import org.jspecify.annotations.Nullable;",
"class Test {",
" interface A<T1 extends @Nullable Object> {",
" T1 function(Object o);",
" }",
" static @Nullable String foo(Object o) {",
" return o.toString();",
" }",
" static void testPositive() {",
" // BUG: Diagnostic contains: referenced method returns @Nullable",
" A<String> p = Test::foo;",
" }",
" static void testNegative() {",
" A<@Nullable String> p = Test::foo;",
" }",
"}")
.doTest();
}

@Test
public void testForLambdasInAnAssignment() {
makeHelper()
Expand Down