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Fix type substitution of "star" types.

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When performing type substitution, there are three types involved, the
substitution site (`this` in TypeImpl.substitute2), the type we are
replacing (`parameterType` in TypeImpl.substitute2), and the
replacement type (`argumentType` in TypeImpl.substitute2).

Previously, we only handled the nullabilities of `this` and
`argumentType`.  This CL adds support for the possibility that
`parameterType` might have nullability "*".  This happens because
TypeParameterElement.type returns a star type, so for instance when
subsituting `int` for `T` in `List<T>` to form `List<int>`, we are
actually substituting `int` for `T*` in `List<T*>`.

Change-Id: I0a61fdc47ec8aa205dc0c539c49ea7799ed4ac05
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/103542
Commit-Queue: Paul Berry <paulberry@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
This commit is contained in:
Paul Berry
2019-05-24 15:43:45 +00:00
committed by commit-bot@chromium.org
parent 77f2603052
commit 3c34c8fa2f
2 changed files with 23 additions and 21 deletions
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pkg/analyzer/lib/src/dart/element/type.dart
+23 -8
View File
@@ -3244,7 +3244,8 @@ class TypeParameterTypeImpl extends TypeImpl implements TypeParameterType {
[List<FunctionTypeAliasElement> prune]) {
int length = parameterTypes.length;
for (int i = 0; i < length; i++) {
if (parameterTypes[i] == this) {
var parameterType = parameterTypes[i];
if (parameterType is TypeParameterTypeImpl && parameterType == this) {
TypeImpl argumentType = argumentTypes[i];
// TODO(scheglov) It should not happen, but sometimes arguments are null.
@@ -3254,15 +3255,29 @@ class TypeParameterTypeImpl extends TypeImpl implements TypeParameterType {
// TODO(scheglov) Proposed substitution rules for nullability.
NullabilitySuffix resultNullability;
NullabilitySuffix parameterNullability =
parameterType.nullabilitySuffix;
NullabilitySuffix argumentNullability = argumentType.nullabilitySuffix;
if (argumentNullability == NullabilitySuffix.question ||
nullabilitySuffix == NullabilitySuffix.question) {
resultNullability = NullabilitySuffix.question;
} else if (argumentNullability == NullabilitySuffix.star ||
nullabilitySuffix == NullabilitySuffix.star) {
resultNullability = NullabilitySuffix.star;
if (parameterNullability == NullabilitySuffix.none) {
if (argumentNullability == NullabilitySuffix.question ||
nullabilitySuffix == NullabilitySuffix.question) {
resultNullability = NullabilitySuffix.question;
} else if (argumentNullability == NullabilitySuffix.star ||
nullabilitySuffix == NullabilitySuffix.star) {
resultNullability = NullabilitySuffix.star;
} else {
resultNullability = NullabilitySuffix.none;
}
} else if (parameterNullability == NullabilitySuffix.star) {
if (argumentNullability == NullabilitySuffix.question ||
nullabilitySuffix == NullabilitySuffix.question) {
resultNullability = NullabilitySuffix.question;
} else {
resultNullability = argumentNullability;
}
} else {
resultNullability = NullabilitySuffix.none;
// We should never be substituting for `T?`.
throw new StateError('Tried to substitute for T?');
}
return argumentType.withNullability(resultNullability);
pkg/analyzer/test/src/diagnostics/default_list_constructor_mismatch_test.dart
-13
View File
@@ -36,10 +36,7 @@ var l = new List<String?>(3);
''');
}
@failingTest
test_inferredType() async {
// This test is failing because summary support is incomplete, which results
// in the constructor having a type of 'List<C*>*'.
await assertErrorsInCode('''
class C {}
List<C> v = List(5);
@@ -48,16 +45,6 @@ List<C> v = List(5);
]);
}
test_starType() async {
// TODO(brianwilkerson) This test is currently taking advantage of the fact
// that the SDK is not opted in, which makes the use of `int` below a
// reference to 'int*'. When it's possible to opt-out in a test this needs
// to be updated to use an explicitly opted out type.
await assertNoErrorsInCode('''
List<int> v = List(5);
''');
}
test_typeParameter() async {
await assertErrorsInCode('''
class C<T> {