#2976. Add type inference tests. Part 2 (#3005)

Add type inference tests. Part 2

LanguageFeatures/Static-access-shorthand/grammar_A03_t02.dart

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+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion We also add . to the tokens that an expression statement cannot
+/// start with. This doesn't affect starting with a double literal like `.42`,
+/// since that's a different token than a single `.`.
+///
+/// @description Checks that it is a compile-time error if an expression
+/// statement is started with `.`.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enum-shorthands
+
+void foo() {}
+
+class C {}
+
+enum E {e0;}
+
+main() {
+  .new;
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  .new();
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  .C();
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  .foo();
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  .e0;
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}

LanguageFeatures/Static-access-shorthand/semantics_A05_t01.dart

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+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion Dart semantics, static and dynamic, do not follow the grammar
+/// precisely. For example, a static member invocation expression of the form
+/// `C.id<T1>(e2)` is treated as an atomic entity for type inference (and
+/// runtime semantics). It’s not a combination of doing a `C.id` tear-off, then
+/// a `<T1>` instantiation and then an `(e2)` invocation. The context type of
+/// that entire expression is used throughout the inference, where
+/// `(e1.id<T1>)(e2)` has `(e1.id<T1>)` in a position where it has no context
+/// type.
+///
+/// Because of that, the specification of the static and runtime semantics of
+/// the new constructs needs to address all the forms `.id`, `.id<typeArgs>`,
+/// `.id(args)`, `.id<typeArgs>(args)`, `.new` or `.new(args)`.
+/// ...
+/// The general rule is that any of the expression forms above, starting with
+/// `.id`, are treated exactly as if they were preceded by a fresh prefixed
+/// identifier `_p.C` which denotes the declaration of the type of the context
+/// type scheme of the entire `<staticMemberShorthand>`.
+///
+/// @description Checks that a named or unnamed constructor can be torn-off
+/// using a shorthand syntax.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enum-shorthands
+
+import '../../Utils/expect.dart';
+
+class C<T> {
+  T t;
+  C(this.t);
+  C.id(this.t);
+}
+
+extension type ET<T>(T t) {
+  ET.id(this.t);
+}
+
+main() {
+  Object? o = C<int>(0);
+  if (o is C<int>) {
+    o = .new;
+    if (o is Function) {
+      Expect.equals(1, o(1).t);
+    }
+  }
+  o = C(0);
+  if (o is C) {
+    o = .id;
+    if (o is Function) {
+      Expect.equals(2, o(2).t);
+    }
+  }
+
+  o = ET<int>(0);
+  if (o is ET) {
+    o = .new;
+    if (o is Function) {
+      Expect.equals(3, o(3));
+    }
+  }
+  o = ET<int>(0);
+  if (o is ET) {
+    o = .id;
+    if (o is Function) {
+      Expect.equals(4, o(4));
+    }
+  }
+}

LanguageFeatures/Static-access-shorthand/type_inference_A01_t07.dart

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+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion Declaration denoted by a type scheme A context type scheme is
+/// said to denote a declaration in some cases. Not all context type schemes
+/// denote a declaration.
+/// If a type scheme `S`:
+/// - has the form `C` or `C<typeArgs>` where `C` is a type introduced by a
+///   declaration `D` which must therefore be a type-introducing declaration,
+///   which currently means a class, mixin, enum or extension type declaration,
+///   then `S` denotes the declaration `D`.
+/// - has the form `S?` or `FutureOr<S>`, and the type scheme S denotes a
+///   declaration D, then so does `S?/FutureOr<S>`. Only the "base type" of the
+///   union type is considered, ensuring that a type scheme denotes at most one
+///   declaration or static namespace.
+/// - has any other form, including type variables, promoted type variables and
+///   `_`, then the type scheme does not denote any declaration or namespace.
+///
+/// @description Checks that in case of context type `_` the type scheme does
+/// not denote any declaration and it is a compile-time error to use a shorthand
+/// in this case.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enum-shorthands
+
+main() {
+  int v1 = (.parse("42")).abs();
+//          ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  int v2 = .parse("42") + 1;
+//         ^
+// [analyzer] unspecified
+// [cfe] unspecified
+
+  dynamic v3 = .parse("42");
+//             ^
+// [analyzer] unspecified
+// [cfe] unspecified
+}

LanguageFeatures/Static-access-shorthand/type_inference_A06_t02.dart

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+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion Expressions of the forms `.new<typeArgs>(args)` or
+/// `.new<typeArgs>` (as a prefix of a `<staticMemberShorthand> <selector>*`
+/// production, or the entire chain) are compile-time errors, just like the
+/// corresponding `T.new<typeArgs>(args)` and `T.new<typeArgs>` already are,
+/// whether used as instantiated tear-off or invoked.
+///
+/// @description Checks that it is a compile-time error to use a shorthand
+/// expression of the form `.new<typeArgs>`.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enum-shorthands
+
+class C<T> {
+  C();
+}
+
+extension type ET<T>(T v) {}
+
+main() {
+  Object? o = C();
+  if (o is C) {
+    o = .new<int>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+  }
+
+  o = ET(0);
+  if (o is ET) {
+    o = .new<int>;
+//      ^
+// [analyzer] unspecified
+// [cfe] unspecified
+  }
+}

LanguageFeatures/Static-access-shorthand/type_inference_A07_t01.dart

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+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion The invocation of a constructor is not using an instantiated
+/// type, it’s behaving as if the constructor was preceded by a raw type, which
+/// type inference should then infer type arguments for. Doing
+/// `List<int> l = .filled(10, 10);` works like doing
+/// `List<int> l = List.filled(10, 10);`, and it is the following downwards
+/// inference with context type `List<int>` that makes it into
+/// `List<int>.filled(10, 10);`. This distinction matters for something like:
+/// ```
+/// List<String> l =
+///   .generate(10, (int i) => i + 1).map((x) => x.toRadixString(16)).toList();
+/// ```
+/// which is equivalent to inserting `List` in front of `.generate`, which will
+/// then be inferred as `List<int>`. In most normal use cases it doesn't matter,
+/// because the context type will fill in the missing type variables, but if the
+/// construction is followed by more selectors, it loses that context type.
+///
+/// @description Checks that in case of a constructor invocation the type
+/// inference occurs as if the shorthand expression is preceded by the raw type
+/// and then a type inference infers the type arguments.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enum-shorthands
+
+import '../../Utils/expect.dart';
+
+class C<T> {
+  T value;
+  C(this.value);
+  C.id(this.value);
+
+  C<int> toInt(int v) => C<int>(v);
+}
+
+extension type ET<T>(T v) {
+  ET.id(this.v);
+
+  ET<int> toInt(int v) => ET<int>(v);
+}
+
+main() {
+  C<int> c1 = .new("String").toInt(1);
+  Expect.equals(1, c1.value);
+
+  C<int> c2 = .id("String").toInt(2);
+  Expect.equals(1, c2.value);
+
+  ET<int> et1 = .new("String").toInt(3);
+  Expect.equals(3, et1.v);
+
+  ET<int> et2 = .id("String").toInt(4);
+  Expect.equals(4, et2.v);
+}

LanguageFeatures/Static-access-shorthand/type_inference_A07_t02.dart

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+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion The invocation of a constructor is not using an instantiated
+/// type, it’s behaving as if the constructor was preceded by a raw type, which
+/// type inference should then infer type arguments for. Doing
+/// `List<int> l = .filled(10, 10);` works like doing
+/// `List<int> l = List.filled(10, 10);`, and it is the following downwards
+/// inference with context type `List<int>` that makes it into
+/// `List<int>.filled(10, 10);`. This distinction matters for something like:
+/// ```
+/// List<String> l =
+///   .generate(10, (int i) => i + 1).map((x) => x.toRadixString(16)).toList();
+/// ```
+/// which is equivalent to inserting `List` in front of `.generate`, which will
+/// then be inferred as `List<int>`. In most normal use cases it doesn’t matter,
+/// because the context type will fill in the missing type variables, but if the
+/// construction is followed by more selectors, it loses that context type.
+///
+/// @description Checks that in case of a constructor invocation the type
+/// inference occurs as if the shorthand expression is preceded by the raw type
+/// and then a type inference infers the type arguments.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enum-shorthands
+
+import '../../Utils/expect.dart';
+
+main() {
+  List<String> l =
+      .generate(10, (int i) => i + 1).map((x) => x.toRadixString(16)).toList();
+  Expect.listEquals(["1", "2", "3", "4", "5", "6", "7", "8", "9", "a"], l);
+
+  num n = .parse("42").abs();
+  Expect.equals(42, n);
+}

LanguageFeatures/Static-access-shorthand/type_inference_A08_t01.dart

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+// Copyright (c) 2024, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/// @assertion Since `!` does propagate a context,
+/// `int x = (.tryParse(input))!;` does work, with a context type scheme of
+/// `int?`, which is enough to allow `.tryParse`. Same for
+/// `int x = .tryParse(input) ?? 0;` which gives the first operand the context
+/// type `int?`.
+///
+/// @description Checks that `!` selector propagates the context type in case of
+/// shorthand expression.
+/// @author [email protected]
+
+// SharedOptions=--enable-experiment=enum-shorthands
+
+import '../../Utils/expect.dart';
+
+class C {
+  int value;
+  C(this.value);
+
+  static C? get id => C(0);
+}
+
+mixin M on C {
+  static M? get id => MC(1);
+}
+class MC = C with M;
+
+enum E {
+  e0(2);
+  final int value;
+  const E(this.value);
+
+  static E? get id => E.e0;
+}
+
+extension type ET(int v) {
+  static ET get id => ET(3);
+}
+
+main() {
+  C c = .id!;
+  Expect.equals(0, c.value);
+
+  c = (.id)!;
+  Expect.equals(0, c.value);
+
+  M m = .id!;
+  Expect.equals(1, m.value);
+
+  m = (.id)!;
+  Expect.equals(1, m.value);
+
+  E e = .id!;
+  Expect.equals(2, e.value);
+
+  e = (.id)!;
+  Expect.equals(2, e.value);
+
+  ET et = .id!;
+  Expect.equals(3, et.v);
+
+  et = (.id)!;
+  Expect.equals(3, et.v);
+}