#3315. Add more declaring constructors tests (#3351)

Author: sgrekhov

LanguageFeatures/Declaring-constructors/grammar_A04_t01.dart

@@ -40,7 +40,7 @@ class const C3.someName(final int v) {
 // [cfe] unspecified
 }
 
-class const C4() {
+class const C4.someName() {
   int? v;
   const this.someName : v = 0;
 //      ^

LanguageFeatures/Declaring-constructors/grammar_A04_t03.dart

@@ -36,7 +36,7 @@ enum E2.someName(final int v) {
 // [cfe] unspecified
 }
 
-enum E3() {
+enum E3.someName() {
   e0;
   final int v;
 //          ^

LanguageFeatures/Declaring-constructors/grammar_A04_t05.dart

@@ -0,0 +1,110 @@
+// 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 The keyword `const` can be specified in the class header when it
+/// contains a primary constructor, and in this case `const` can not be
+/// specified in the part of the primary constructor that occurs in the body
+/// (that is, the declaration that starts with this and contains an initializer
+/// list and/or a constructor body, if any). The rationale is that when the
+/// class header contains any parts of a declaring constructor, the class header
+/// must be the location where all parts of the signature of that primary
+/// constructor are specified.
+///
+/// @description Check that it is a compile-time error if a class header
+/// contains a primary constructor and the keyword const is specified before its
+/// `this` part in the body.
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=declaring-constructors
+
+class C1() {
+  final int v;
+  const this : v = 0;
+//^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+class C2(int v) {
+  const this : assert(v > 0);
+//^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+class C3.someName(final int v) {
+  const this.someName : assert(v > 0);
+//^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+class C4.someName() {
+  int v;
+  const this.someName : v = 0;
+//^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+extension type ET1(int v) {
+  const this: assert(v > 0);
+//^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+extension type ET2.someName(int v) {
+  const this.someName: assert(v > 0);
+//^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+enum E1() {
+  e0;
+  final int v;
+  const this : v = 0;
+//^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+enum E2(int v) {
+  e0(1);
+  const this : assert(v > 0);
+//^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+enum E3.someName(final int v) {
+  e0.someName(0);
+  const this.someName : assert(v > 0);
+//^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+enum E4.someName() {
+  e0.someName();
+  final int v;
+  const this.someName : v = 0;
+//^^^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+main() {
+  print(C1);
+  print(C2);
+  print(C3);
+  print(C4);
+  print(ET1);
+  print(ET2);
+  print(E1);
+  print(E2);
+  print(E3);
+  print(E4);
+}

LanguageFeatures/Declaring-constructors/static_processing_A25_t05.dart

@@ -0,0 +1,75 @@
+// 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 The ability to use `new` rather than the class name in
+/// declarations of ordinary (non-declaring) constructors is purely syntactic.
+/// The static analysis and meaning of such constructors is identical to the
+/// form that uses the class name.
+///
+/// @description Check that it is a compile-time error if a `new` keyword is
+/// used as a constructor name in the initializer list.
+/// @author sgrekhov22@gmail.com
+
+// SharedOptions=--enable-experiment=declaring-constructors
+
+class C1 {
+  C1();
+  C1.someName() : new();
+//                ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+class C2 {
+  C2() : new.someName();
+//       ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  C2.someName();
+}
+
+extension type ET1._(int v) {
+  ET1(this.v);
+  ET1.someName() : new(0);
+//                 ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+extension type ET2._(int v) {
+  ET2() : new.someName(0);
+//        ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  ET2.someName(this.v);
+}
+
+enum E1 {
+  e0;
+
+  const E1();
+  const E1.someName() : new();
+//                      ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+}
+
+enum E2 {
+  e0;
+
+  const ET2() : new.someName();
+//              ^^^
+// [analyzer] unspecified
+// [cfe] unspecified
+  const ET2.someName();
+}
+
+main() {
+  print(C1);
+  print(C2);
+  print(ET1);
+  print(ET2);
+  print(E1);
+  print(E2);
+}