dart-lang#3057. Add flow analysis tests for throw expression

TypeSystem/flow-analysis/reachability_A10_t01.dart

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+// Copyright (c) 2025, 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 throw: If `N` is a throw expression of the form `throw E1`, then:
+/// - Let `before(E1) = before(N)`
+/// - Let `after(N) = unreachable(after(E1))`
+///
+/// @description Checks that a code after throw expression is unreachable.
+/// @author [email protected]
+
+main() {
+  late int i;
+  if ((() => false)()) {
+    throw "Dead code after this point";
+    i = 42; // Variable is initialized in a dead code. This leaves it definitely unassigned
+  }
+  i;  // It is an error to read a local late variable when it is definitely unassigned.
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}

TypeSystem/flow-analysis/reachability_A10_t02.dart

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+// Copyright (c) 2025, 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 throw: If `N` is a throw expression of the form `throw E1`, then:
+/// - Let `before(E1) = before(N)`
+/// - Let `after(N) = unreachable(after(E1))`
+///
+/// @description Checks that a code after throw expression is unreachable. Test
+/// collection literals.
+/// @author [email protected]
+
+test1() {
+  late int i;
+  if ((() => false)()) {
+    [
+      0,
+      throw "Dead code after this point",
+      i = 42 // Variable is initialized in a dead code. This leaves it definitely unassigned
+    ];
+  }
+  i;  // It is an error to read a local late variable when it is definitely unassigned.
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+test2() {
+  late int i;
+  if ((() => false)()) {
+    <int>{
+      0,
+      throw "Dead code after this point",
+      i = 42
+    };
+  }
+  i;
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+test3() {
+  late int i;
+  if ((() => false)()) {
+    <String, int>{
+      "key1": 0,
+      "key2": throw "Dead code after this point",
+      "key3": i = 42
+    };
+  }
+  i;
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+test4() {
+  late int i;
+  if ((() => false)()) {
+    <int, String>{
+      0: "value1",
+      throw "Dead code after this point": "value2",
+      i = 42: "value3"
+    };
+  }
+  i;
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+main() {
+  print(test1);
+  print(test2);
+  print(test3);
+  print(test4);
+}

TypeSystem/flow-analysis/reachability_A10_t03.dart

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+// Copyright (c) 2025, 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 throw: If `N` is a throw expression of the form `throw E1`, then:
+/// - Let `before(E1) = before(N)`
+/// - Let `after(N) = unreachable(after(E1))`
+///
+/// @description Checks that a code after throw expression is unreachable. Test
+/// collection literals.
+/// @author [email protected]
+
+test1() {
+  late int i;
+  if ((() => false)()) {
+    [
+      0,
+      if (throw "Dead code after this point")
+        i = 42,
+      i = 42
+    ];
+  }
+  i;  // It is an error to read a local late variable when it is definitely unassigned.
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+test2() {
+  late int i;
+  if ((() => false)()) {
+    <int>{
+      0,
+      if (throw "Dead code after this point")
+        i = 42,
+      i = 42
+    };
+  }
+  i;
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+test3() {
+  late int i;
+  if ((() => false)()) {
+    <String, int>{
+      "key1": 0,
+      if (throw "Dead code after this point")
+        "key2": i = 42,
+      "key3": i = 42
+    };
+  }
+  i;
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+test4() {
+  late int i;
+  if ((() => false)()) {
+    <int, String>{
+      0: "value1",
+      if (throw "Dead code after this point")
+        i = 42: "value2",
+      i = 0: "value3"
+    };
+  }
+  i;
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+main() {
+  print(test1);
+  print(test2);
+  print(test3);
+  print(test4);
+}

TypeSystem/flow-analysis/reachability_A10_t04.dart

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+// Copyright (c) 2025, 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 throw: If `N` is a throw expression of the form `throw E1`, then:
+/// - Let `before(E1) = before(N)`
+/// - Let `after(N) = unreachable(after(E1))`
+///
+/// @description Checks that a code after throw expression is unreachable. Test
+/// `for(;;)` loop in list literals.
+/// @author [email protected]
+
+test1() {
+  late int i;
+  if ((() => false)()) {
+    [
+      0,
+      for (throw "Dead code after this point";;)
+        i = 42,
+      i = 42
+    ];
+  }
+  i;  // It is an error to read a local late variable when it is definitely unassigned.
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+test2() {
+  late int i;
+  if ((() => false)()) {
+    [
+      0,
+      for (;throw "Dead code after this point";)
+        i = 42,
+      i = 42
+    ];
+  }
+  i;
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+test3() {
+  late int i;
+  if ((() => false)()) {
+    [
+      0,
+      for (;; throw "Dead code after this statement")
+        1,
+      i = 42
+    ];
+  }
+  i;
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+test4() {
+  late int i;
+  if ((() => false)()) {
+    [
+      0,
+      for (var j = 0; j < 0; throw "Not a dead code after this point")
+        i = 42
+    ];
+  }
+  i; // Ok
+}
+
+main() {
+  print(test1);
+  print(test2);
+  print(test3);
+  print(test4);
+}

TypeSystem/flow-analysis/reachability_A10_t05.dart

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+// Copyright (c) 2025, 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 throw: If `N` is a throw expression of the form `throw E1`, then:
+/// - Let `before(E1) = before(N)`
+/// - Let `after(N) = unreachable(after(E1))`
+///
+/// @description Checks that a code after throw expression is unreachable. Test
+/// `for(;;)` loop in set literals.
+/// @author [email protected]
+
+test1() {
+  late int i;
+  if ((() => false)()) {
+    <int>{
+      0,
+      for (throw "Dead code after this point";;)
+        i = 42,
+      i = 42
+    };
+  }
+  i;  // It is an error to read a local late variable when it is definitely unassigned.
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+test2() {
+  late int i;
+  if ((() => false)()) {
+    <int>{
+      0,
+      for (; throw "Dead code after this point";)
+        i = 42,
+      i = 42
+    };
+  }
+  i;
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+test3() {
+  late int i;
+  if ((() => false)()) {
+    <int>{
+      0,
+      for (;; throw "Dead code after this statement")
+        1,
+      i = 42
+    };
+  }
+  i;
+//^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+test4() {
+  late int i;
+  if ((() => false)()) {
+    <int>{
+      0,
+      for (var j = 0; j < 0; throw "Not a dead code after this point")
+        i = 42,
+    };
+  }
+  i; // Ok
+}
+
+main() {
+  print(test1);
+  print(test2);
+  print(test3);
+  print(test4);
+}