#993. Added tests checking that Struct fields cannot have initializers

LibTest/ffi/Struct/Struct_A09_t01.dart

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+/*
+ * Copyright (c) 2021, 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 All field declarations in a Struct subclass declaration must be
+ * marked external. You cannot create instances of the class, only have it point
+ * to existing native memory, so there is no memory in which to store non-native
+ * fields. External fields also cannot be initialized by constructors since no
+ * Dart object is being created.
+ *
+ * @description Checks that all field declarations in a Struct subclass
+ * declaration cannot have initializers
+ * @author sgrekhov@unipro.ru
+ */
+import "dart:ffi";
+
+class S1 extends Struct {
+  @Int16()
+  int i = 42;
+//    ^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+void main() {
+  S1? s1;
+}

LibTest/ffi/Struct/Struct_A09_t02.dart

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+/*
+ * Copyright (c) 2021, 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 All field declarations in a Struct subclass declaration must be
+ * marked external. You cannot create instances of the class, only have it point
+ * to existing native memory, so there is no memory in which to store non-native
+ * fields. External fields also cannot be initialized by constructors since no
+ * Dart object is being created.
+ *
+ * @description Checks that all field declarations in a Struct subclass
+ * declaration cannot have initializers
+ * @author sgrekhov@unipro.ru
+ */
+import "dart:ffi";
+
+class S1 extends Struct {
+  @Double()
+  double d = 3.14;
+//       ^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+void main() {
+  S1? s1;
+}

LibTest/ffi/Struct/Struct_A09_t03.dart

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+/*
+ * Copyright (c) 2021, 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 All field declarations in a Struct subclass declaration must be
+ * marked external. You cannot create instances of the class, only have it point
+ * to existing native memory, so there is no memory in which to store non-native
+ * fields. External fields also cannot be initialized by constructors since no
+ * Dart object is being created.
+ *
+ * @description Checks that all field declarations in a Struct subclass
+ * declaration cannot have initializers
+ * @author sgrekhov@unipro.ru
+ */
+import "dart:ffi";
+
+class S1 extends Struct {
+  Pointer<S1> next = new Pointer.fromAddress(42);
+//            ^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+void main() {
+  S1? s1;
+}