[cfe] Const constructors enabled with const functions.

Change-Id: Ic0597bf7ec69811ec822539ef5df1e24ef1b9884
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/194560
Reviewed-by: Jake Macdonald <jakemac@google.com>
Reviewed-by: Bob Nystrom <rnystrom@google.com>
Reviewed-by: Dmitry Stefantsov <dmitryas@google.com>
Commit-Queue: Kallen Tu <kallentu@google.com>

pkg/front_end/lib/src/fasta/kernel/constant_evaluator.dart

@@ -1050,6 +1050,27 @@ class ConstantEvaluator implements ExpressionVisitor<Constant> {
         'No valid constant returned from the execution of $statement.');
   }
 
+  /// Returns [null] on success and an error-"constant" on failure, as such the
+  /// return value should be checked.
+  AbortConstant executeConstructorBody(Constructor constructor) {
+    final Statement body = constructor.function.body;
+    StatementConstantEvaluator statementEvaluator =
+        new StatementConstantEvaluator(this);
+    ExecutionStatus status = body.accept(statementEvaluator);
+    if (status is AbortStatus) {
+      return status.error;
+    } else if (status is ReturnStatus) {
+      if (status.value == null) return null;
+      // Should not be reachable.
+      return createInvalidExpressionConstant(
+          constructor, "Constructors can't have a return value.");
+    } else if (status is! ProceedStatus) {
+      return createInvalidExpressionConstant(
+          constructor, "Invalid execution status of constructor body.");
+    }
+    return null;
+  }
+
   /// Create an error-constant indicating that an error has been detected during
   /// constant evaluation.
   AbortConstant createErrorConstant(TreeNode node, Message message,
@@ -1508,7 +1529,8 @@ class ConstantEvaluator implements ExpressionVisitor<Constant> {
           node, 'Non-const constructor invocation.');
     }
     if (constructor.function.body != null &&
-        constructor.function.body is! EmptyStatement) {
+        constructor.function.body is! EmptyStatement &&
+        !enableConstFunctions) {
       // Probably unreachable.
       return createInvalidExpressionConstant(
           node,
@@ -1822,6 +1844,12 @@ class ConstantEvaluator implements ExpressionVisitor<Constant> {
       for (UnevaluatedConstant constant in env.unevaluatedUnreadConstants) {
         instanceBuilder.unusedArguments.add(extract(constant));
       }
+
+      if (enableConstFunctions && constructor.function != null) {
+        AbortConstant error = executeConstructorBody(constructor);
+        if (error != null) return error;
+      }
+
       return null;
     });
   }
@@ -3441,6 +3469,10 @@ class StatementConstantEvaluator extends StatementVisitor<ExecutionStatus> {
     return const ProceedStatus();
   }
 
+  @override
+  ExecutionStatus visitEmptyStatement(EmptyStatement node) =>
+      const ProceedStatus();
+
   @override
   ExecutionStatus visitFunctionDeclaration(FunctionDeclaration node) {
     final EvaluationEnvironment newEnv =
@@ -3514,8 +3546,13 @@ class StatementConstantEvaluator extends StatementVisitor<ExecutionStatus> {
   }
 
   @override
-  ExecutionStatus visitReturnStatement(ReturnStatement node) =>
-      new ReturnStatus(evaluate(node.expression));
+  ExecutionStatus visitReturnStatement(ReturnStatement node) {
+    Constant result;
+    if (node.expression != null) {
+      result = evaluate(node.expression);
+    }
+    return new ReturnStatus(result);
+  }
 
   @override
   ExecutionStatus visitSwitchStatement(SwitchStatement node) {

pkg/front_end/lib/src/fasta/source/outline_builder.dart

@@ -1176,7 +1176,9 @@ class OutlineBuilder extends StackListenerImpl {
 
     declarationBuilder.resolveTypes(typeVariables, libraryBuilder);
     if (constructorName != null) {
-      if (isConst && bodyKind != MethodBody.Abstract) {
+      if (isConst &&
+          bodyKind != MethodBody.Abstract &&
+          !libraryBuilder.enableConstFunctionsInLibrary) {
         addProblem(messageConstConstructorWithBody, varFinalOrConstOffset, 5);
         modifiers &= ~constMask;
       }

pkg/front_end/testcases/const_functions/const_functions_const_ctor.dart

@@ -0,0 +1,28 @@
+// 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.
+
+// Tests const constructors with a body which are enabled with const functions.
+
+import "package:expect/expect.dart";
+
+const printString = "print";
+const var1 = Simple(printString);
+class Simple {
+  final String name;
+
+  const Simple(this.name) {
+    assert(this.name == printString);
+  }
+}
+
+const var2 = A();
+class A {
+  const A() {
+    return;
+  }
+}
+
+void main() {
+  Expect.equals(var1.name, printString);
+}

pkg/front_end/testcases/const_functions/const_functions_const_ctor.dart.strong.expect

@@ -0,0 +1,39 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "package:expect/expect.dart" as exp;
+
+import "package:expect/expect.dart";
+
+class Simple extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple
+    : self::Simple::name = name, super core::Object::•() {
+    assert(this.{self::Simple::name}.{core::String::==}(#C1));
+  }
+}
+class A extends core::Object /*hasConstConstructor*/  {
+  const constructor •() → self::A
+    : super core::Object::•() {
+    return;
+  }
+}
+static const field core::String printString = #C1;
+static const field self::Simple var1 = #C2;
+static const field self::A var2 = #C3;
+static method main() → void {
+  exp::Expect::equals((#C2).{self::Simple::name}, #C1);
+}
+
+constants  {
+  #C1 = "print"
+  #C2 = self::Simple {name:#C1}
+  #C3 = self::A {}
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///const_functions_const_ctor.dart:
+- Simple. (from org-dartlang-testcase:///const_functions_const_ctor.dart:14:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)
+- A. (from org-dartlang-testcase:///const_functions_const_ctor.dart:21:9)

pkg/front_end/testcases/const_functions/const_functions_const_ctor.dart.strong.transformed.expect

@@ -0,0 +1,39 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "package:expect/expect.dart" as exp;
+
+import "package:expect/expect.dart";
+
+class Simple extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple
+    : self::Simple::name = name, super core::Object::•() {
+    assert(this.{self::Simple::name}.{core::String::==}(#C1));
+  }
+}
+class A extends core::Object /*hasConstConstructor*/  {
+  const constructor •() → self::A
+    : super core::Object::•() {
+    return;
+  }
+}
+static const field core::String printString = #C1;
+static const field self::Simple var1 = #C2;
+static const field self::A var2 = #C3;
+static method main() → void {
+  exp::Expect::equals((#C2).{self::Simple::name}, #C1);
+}
+
+constants  {
+  #C1 = "print"
+  #C2 = self::Simple {name:#C1}
+  #C3 = self::A {}
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///const_functions_const_ctor.dart:
+- Simple. (from org-dartlang-testcase:///const_functions_const_ctor.dart:14:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)
+- A. (from org-dartlang-testcase:///const_functions_const_ctor.dart:21:9)

pkg/front_end/testcases/const_functions/const_functions_const_ctor.dart.textual_outline.expect

@@ -0,0 +1,12 @@
+import "package:expect/expect.dart";
+const printString = "print";
+const var1 = Simple(printString);
+class Simple {
+  final String name;
+  const Simple(this.name) {}
+}
+const var2 = A();
+class A {
+  const A() {}
+}
+void main() {}

pkg/front_end/testcases/const_functions/const_functions_const_ctor.dart.weak.expect

@@ -0,0 +1,39 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "package:expect/expect.dart" as exp;
+
+import "package:expect/expect.dart";
+
+class Simple extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple
+    : self::Simple::name = name, super core::Object::•() {
+    assert(this.{self::Simple::name}.{core::String::==}(#C1));
+  }
+}
+class A extends core::Object /*hasConstConstructor*/  {
+  const constructor •() → self::A
+    : super core::Object::•() {
+    return;
+  }
+}
+static const field core::String printString = #C1;
+static const field self::Simple var1 = #C2;
+static const field self::A var2 = #C3;
+static method main() → void {
+  exp::Expect::equals((#C2).{self::Simple::name}, #C1);
+}
+
+constants  {
+  #C1 = "print"
+  #C2 = self::Simple {name:#C1}
+  #C3 = self::A {}
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///const_functions_const_ctor.dart:
+- Simple. (from org-dartlang-testcase:///const_functions_const_ctor.dart:14:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)
+- A. (from org-dartlang-testcase:///const_functions_const_ctor.dart:21:9)

pkg/front_end/testcases/const_functions/const_functions_const_ctor.dart.weak.outline.expect

@@ -0,0 +1,28 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+import "package:expect/expect.dart";
+
+class Simple extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple
+    : self::Simple::name = name, super core::Object::•()
+    ;
+}
+class A extends core::Object /*hasConstConstructor*/  {
+  const constructor •() → self::A
+    : super core::Object::•()
+    ;
+}
+static const field core::String printString = "print";
+static const field self::Simple var1 = const self::Simple::•(self::printString);
+static const field self::A var2 = const self::A::•();
+static method main() → void
+  ;
+
+
+Extra constant evaluation status:
+Evaluated: ConstructorInvocation @ org-dartlang-testcase:///const_functions_const_ctor.dart:10:14 -> InstanceConstant(const Simple{Simple.name: "print"})
+Evaluated: ConstructorInvocation @ org-dartlang-testcase:///const_functions_const_ctor.dart:19:14 -> InstanceConstant(const A{})
+Extra constant evaluation: evaluated: 3, effectively constant: 2

pkg/front_end/testcases/const_functions/const_functions_const_ctor.dart.weak.transformed.expect

@@ -0,0 +1,39 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+import "package:expect/expect.dart" as exp;
+
+import "package:expect/expect.dart";
+
+class Simple extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple
+    : self::Simple::name = name, super core::Object::•() {
+    assert(this.{self::Simple::name}.{core::String::==}(#C1));
+  }
+}
+class A extends core::Object /*hasConstConstructor*/  {
+  const constructor •() → self::A
+    : super core::Object::•() {
+    return;
+  }
+}
+static const field core::String printString = #C1;
+static const field self::Simple var1 = #C2;
+static const field self::A var2 = #C3;
+static method main() → void {
+  exp::Expect::equals((#C2).{self::Simple::name}, #C1);
+}
+
+constants  {
+  #C1 = "print"
+  #C2 = self::Simple {name:#C1}
+  #C3 = self::A {}
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///const_functions_const_ctor.dart:
+- Simple. (from org-dartlang-testcase:///const_functions_const_ctor.dart:14:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)
+- A. (from org-dartlang-testcase:///const_functions_const_ctor.dart:21:9)

pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart

@@ -0,0 +1,41 @@
+// 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.
+
+// Tests erroneous const constructors with a body which are enabled with const
+// functions.
+
+import "package:expect/expect.dart";
+
+const printString = "print";
+
+const var1 = Simple(printString);
+class Simple {
+  final String name;
+
+  const Simple(this.name) {
+    assert(this.name != printString);
+  }
+}
+
+const var2 = Simple2(printString);
+class Simple2 {
+  final String name;
+
+  const Simple2(this.name) {
+    return Simple2(this.name);
+  }
+}
+
+const var3 = B();
+class A {
+  const A() {
+    assert(1 == 2);
+  }
+}
+
+class B extends A {
+  const B() : super();
+}
+
+void main() {}

pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart.strong.expect

@@ -0,0 +1,83 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:26:5: Error: Constructors can't have a return type.
+// Try removing the return type.
+//     return Simple2(this.name);
+//     ^
+//
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:12:14: Error: Constant evaluation error:
+// const var1 = Simple(printString);
+//              ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:17:22: Context: This assertion failed.
+//     assert(this.name != printString);
+//                      ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:12:7: Context: While analyzing:
+// const var1 = Simple(printString);
+//       ^
+//
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:30:14: Error: Constant evaluation error:
+// const var3 = B();
+//              ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:33:14: Context: This assertion failed.
+//     assert(1 == 2);
+//              ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:30:7: Context: While analyzing:
+// const var3 = B();
+//       ^
+//
+import self as self;
+import "dart:core" as core;
+
+import "package:expect/expect.dart";
+
+class Simple extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple
+    : self::Simple::name = name, super core::Object::•() {
+    assert(!this.{self::Simple::name}.{core::String::==}(#C1));
+  }
+}
+class Simple2 extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple2
+    : self::Simple2::name = name, super core::Object::•() {
+    invalid-expression "pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:26:5: Error: Constructors can't have a return type.
+Try removing the return type.
+    return Simple2(this.name);
+    ^";
+  }
+}
+class A extends core::Object /*hasConstConstructor*/  {
+  const constructor •() → self::A
+    : super core::Object::•() {
+    assert(1.{core::num::==}(2));
+  }
+}
+class B extends self::A /*hasConstConstructor*/  {
+  const constructor •() → self::B
+    : super self::A::•()
+    ;
+}
+static const field core::String printString = #C1;
+static const field self::Simple var1 = invalid-expression "This assertion failed.";
+static const field self::Simple2 var2 = invalid-expression "pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:26:5: Error: Constructors can't have a return type.
+Try removing the return type.
+    return Simple2(this.name);
+    ^";
+static const field self::B var3 = invalid-expression "This assertion failed.";
+static method main() → void {}
+
+constants  {
+  #C1 = "print"
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///const_functions_const_ctor_error.dart:
+- Simple. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:16:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)
+- Simple2. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:25:9)
+- B. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:38:9)
+- A. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:32:9)

pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart.strong.transformed.expect

@@ -0,0 +1,87 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:26:5: Error: Constructors can't have a return type.
+// Try removing the return type.
+//     return Simple2(this.name);
+//     ^
+//
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:12:14: Error: Constant evaluation error:
+// const var1 = Simple(printString);
+//              ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:17:22: Context: This assertion failed.
+//     assert(this.name != printString);
+//                      ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:12:7: Context: While analyzing:
+// const var1 = Simple(printString);
+//       ^
+//
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:30:14: Error: Constant evaluation error:
+// const var3 = B();
+//              ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:33:14: Context: This assertion failed.
+//     assert(1 == 2);
+//              ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:30:7: Context: While analyzing:
+// const var3 = B();
+//       ^
+//
+import self as self;
+import "dart:core" as core;
+
+import "package:expect/expect.dart";
+
+class Simple extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple
+    : self::Simple::name = name, super core::Object::•() {
+    assert(!this.{self::Simple::name}.{core::String::==}(#C1));
+  }
+}
+class Simple2 extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple2
+    : self::Simple2::name = name, super core::Object::•() {
+    invalid-expression "pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:26:5: Error: Constructors can't have a return type.
+Try removing the return type.
+    return Simple2(this.name);
+    ^";
+  }
+}
+class A extends core::Object /*hasConstConstructor*/  {
+  const constructor •() → self::A
+    : super core::Object::•() {
+    assert(1.{core::num::==}(2));
+  }
+}
+class B extends self::A /*hasConstConstructor*/  {
+  const constructor •() → self::B
+    : super self::A::•()
+    ;
+}
+static const field core::String printString = #C1;
+static const field self::Simple var1 = invalid-expression "This assertion failed.";
+static const field self::Simple2 var2 = invalid-expression "pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:26:5: Error: Constructors can't have a return type.
+Try removing the return type.
+    return Simple2(this.name);
+    ^";
+static const field self::B var3 = invalid-expression "This assertion failed.";
+static method main() → void {}
+
+constants  {
+  #C1 = "print"
+}
+
+Extra constant evaluation status:
+Evaluated: MethodInvocation @ org-dartlang-testcase:///const_functions_const_ctor_error.dart:33:14 -> BoolConstant(false)
+Extra constant evaluation: evaluated: 7, effectively constant: 1
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///const_functions_const_ctor_error.dart:
+- Simple. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:16:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)
+- Simple2. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:25:9)
+- B. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:38:9)
+- A. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:32:9)

pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart.textual_outline.expect

@@ -0,0 +1,20 @@
+import "package:expect/expect.dart";
+const printString = "print";
+const var1 = Simple(printString);
+class Simple {
+  final String name;
+  const Simple(this.name) {}
+}
+const var2 = Simple2(printString);
+class Simple2 {
+  final String name;
+  const Simple2(this.name) {}
+}
+const var3 = B();
+class A {
+  const A() {}
+}
+class B extends A {
+  const B() : super();
+}
+void main() {}

pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart.weak.expect

@@ -0,0 +1,83 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:26:5: Error: Constructors can't have a return type.
+// Try removing the return type.
+//     return Simple2(this.name);
+//     ^
+//
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:12:14: Error: Constant evaluation error:
+// const var1 = Simple(printString);
+//              ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:17:22: Context: This assertion failed.
+//     assert(this.name != printString);
+//                      ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:12:7: Context: While analyzing:
+// const var1 = Simple(printString);
+//       ^
+//
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:30:14: Error: Constant evaluation error:
+// const var3 = B();
+//              ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:33:14: Context: This assertion failed.
+//     assert(1 == 2);
+//              ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:30:7: Context: While analyzing:
+// const var3 = B();
+//       ^
+//
+import self as self;
+import "dart:core" as core;
+
+import "package:expect/expect.dart";
+
+class Simple extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple
+    : self::Simple::name = name, super core::Object::•() {
+    assert(!this.{self::Simple::name}.{core::String::==}(#C1));
+  }
+}
+class Simple2 extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple2
+    : self::Simple2::name = name, super core::Object::•() {
+    invalid-expression "pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:26:5: Error: Constructors can't have a return type.
+Try removing the return type.
+    return Simple2(this.name);
+    ^";
+  }
+}
+class A extends core::Object /*hasConstConstructor*/  {
+  const constructor •() → self::A
+    : super core::Object::•() {
+    assert(1.{core::num::==}(2));
+  }
+}
+class B extends self::A /*hasConstConstructor*/  {
+  const constructor •() → self::B
+    : super self::A::•()
+    ;
+}
+static const field core::String printString = #C1;
+static const field self::Simple var1 = invalid-expression "This assertion failed.";
+static const field self::Simple2 var2 = invalid-expression "pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:26:5: Error: Constructors can't have a return type.
+Try removing the return type.
+    return Simple2(this.name);
+    ^";
+static const field self::B var3 = invalid-expression "This assertion failed.";
+static method main() → void {}
+
+constants  {
+  #C1 = "print"
+}
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///const_functions_const_ctor_error.dart:
+- Simple. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:16:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)
+- Simple2. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:25:9)
+- B. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:38:9)
+- A. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:32:9)

pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart.weak.outline.expect

@@ -0,0 +1,41 @@
+library /*isNonNullableByDefault*/;
+import self as self;
+import "dart:core" as core;
+
+import "package:expect/expect.dart";
+
+class Simple extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple
+    : self::Simple::name = name, super core::Object::•()
+    ;
+}
+class Simple2 extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple2
+    : self::Simple2::name = name, super core::Object::•()
+    ;
+}
+class A extends core::Object /*hasConstConstructor*/  {
+  const constructor •() → self::A
+    : super core::Object::•()
+    ;
+}
+class B extends self::A /*hasConstConstructor*/  {
+  const constructor •() → self::B
+    : super self::A::•()
+    ;
+}
+static const field core::String printString = "print";
+static const field self::Simple var1 = const self::Simple::•(self::printString);
+static const field self::Simple2 var2 = const self::Simple2::•(self::printString);
+static const field self::B var3 = const self::B::•();
+static method main() → void
+  ;
+
+
+Extra constant evaluation status:
+Evaluated: ConstructorInvocation @ org-dartlang-testcase:///const_functions_const_ctor_error.dart:12:14 -> InstanceConstant(const Simple{Simple.name: "print"})
+Evaluated: ConstructorInvocation @ org-dartlang-testcase:///const_functions_const_ctor_error.dart:21:14 -> InstanceConstant(const Simple2{Simple2.name: "print"})
+Evaluated: ConstructorInvocation @ org-dartlang-testcase:///const_functions_const_ctor_error.dart:30:14 -> InstanceConstant(const B{})
+Extra constant evaluation: evaluated: 5, effectively constant: 3

pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart.weak.transformed.expect

@@ -0,0 +1,87 @@
+library /*isNonNullableByDefault*/;
+//
+// Problems in library:
+//
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:26:5: Error: Constructors can't have a return type.
+// Try removing the return type.
+//     return Simple2(this.name);
+//     ^
+//
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:12:14: Error: Constant evaluation error:
+// const var1 = Simple(printString);
+//              ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:17:22: Context: This assertion failed.
+//     assert(this.name != printString);
+//                      ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:12:7: Context: While analyzing:
+// const var1 = Simple(printString);
+//       ^
+//
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:30:14: Error: Constant evaluation error:
+// const var3 = B();
+//              ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:33:14: Context: This assertion failed.
+//     assert(1 == 2);
+//              ^
+// pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:30:7: Context: While analyzing:
+// const var3 = B();
+//       ^
+//
+import self as self;
+import "dart:core" as core;
+
+import "package:expect/expect.dart";
+
+class Simple extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple
+    : self::Simple::name = name, super core::Object::•() {
+    assert(!this.{self::Simple::name}.{core::String::==}(#C1));
+  }
+}
+class Simple2 extends core::Object /*hasConstConstructor*/  {
+  final field core::String name;
+  const constructor •(core::String name) → self::Simple2
+    : self::Simple2::name = name, super core::Object::•() {
+    invalid-expression "pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:26:5: Error: Constructors can't have a return type.
+Try removing the return type.
+    return Simple2(this.name);
+    ^";
+  }
+}
+class A extends core::Object /*hasConstConstructor*/  {
+  const constructor •() → self::A
+    : super core::Object::•() {
+    assert(1.{core::num::==}(2));
+  }
+}
+class B extends self::A /*hasConstConstructor*/  {
+  const constructor •() → self::B
+    : super self::A::•()
+    ;
+}
+static const field core::String printString = #C1;
+static const field self::Simple var1 = invalid-expression "This assertion failed.";
+static const field self::Simple2 var2 = invalid-expression "pkg/front_end/testcases/const_functions/const_functions_const_ctor_error.dart:26:5: Error: Constructors can't have a return type.
+Try removing the return type.
+    return Simple2(this.name);
+    ^";
+static const field self::B var3 = invalid-expression "This assertion failed.";
+static method main() → void {}
+
+constants  {
+  #C1 = "print"
+}
+
+Extra constant evaluation status:
+Evaluated: MethodInvocation @ org-dartlang-testcase:///const_functions_const_ctor_error.dart:33:14 -> BoolConstant(false)
+Extra constant evaluation: evaluated: 7, effectively constant: 1
+
+
+Constructor coverage from constants:
+org-dartlang-testcase:///const_functions_const_ctor_error.dart:
+- Simple. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:16:9)
+- Object. (from org-dartlang-sdk:///sdk/lib/core/object.dart:25:9)
+- Simple2. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:25:9)
+- B. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:38:9)
+- A. (from org-dartlang-testcase:///const_functions_const_ctor_error.dart:32:9)

pkg/front_end/testcases/textual_outline.status

@@ -20,9 +20,11 @@ regress/issue_39035.crash: EmptyOutput
 regress/issue_39091_2: EmptyOutput
 regress/utf_16_le_content.crash: EmptyOutput
 
+const_functions/const_functions_const_ctor: FormatterCrash
+const_functions/const_functions_const_ctor_error: FormatterCrash
+const_functions/const_functions_const_factory: FormatterCrash
 dart2js/late_fields: FormatterCrash
 dart2js/late_statics: FormatterCrash
-const_functions/const_functions_const_factory: FormatterCrash
 extensions/extension_constructor: FormatterCrash
 extensions/extension_field_with_type_parameter_usage: FormatterCrash
 extensions/issue38600: FormatterCrash

tests/language/const_functions/const_functions_const_ctor_disabled_test.dart

@@ -0,0 +1,23 @@
+// 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.
+
+// Tests const constructors with a body are disabled without const functions.
+
+import "package:expect/expect.dart";
+
+const printString = "print";
+const var1 = Simple(printString);
+//           ^
+// [cfe] Cannot invoke a non-'const' constructor where a const expression is expected.
+class Simple {
+  final String name;
+
+  const Simple(this.name) {
+//^
+// [cfe] A const constructor can't have a body.
+  //                      ^
+  // [analyzer] SYNTACTIC_ERROR.CONST_CONSTRUCTOR_WITH_BODY
+    assert(this.name == printString);
+  }
+}

tests/language/const_functions/const_functions_const_ctor_error_test.dart

@@ -0,0 +1,55 @@
+// 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.
+
+// Tests erroneous const constructors with a body which are enabled with const
+// functions.
+
+// SharedOptions=--enable-experiment=const-functions
+
+import "package:expect/expect.dart";
+
+const printString = "print";
+
+const var1 = Simple(printString);
+//           ^
+// [cfe] Constant evaluation error:
+class Simple {
+  final String name;
+
+  const Simple(this.name) {
+//                        ^
+// [analyzer] SYNTACTIC_ERROR.CONST_CONSTRUCTOR_WITH_BODY
+    assert(this.name != printString);
+  }
+}
+
+const var2 = Simple2(printString);
+class Simple2 {
+  final String name;
+
+  const Simple2(this.name) {
+//                         ^
+// [analyzer] SYNTACTIC_ERROR.CONST_CONSTRUCTOR_WITH_BODY
+    return Simple2(this.name);
+//  ^
+// [cfe] Constructors can't have a return type.
+//         ^^^^^^^^^^^^^^^^^^
+// [analyzer] COMPILE_TIME_ERROR.RETURN_IN_GENERATIVE_CONSTRUCTOR
+  }
+}
+
+const var3 = B();
+//           ^
+// [cfe] Constant evaluation error:
+class A {
+  const A() {
+  //        ^
+  // [analyzer] SYNTACTIC_ERROR.CONST_CONSTRUCTOR_WITH_BODY
+    assert(1 == 2);
+  }
+}
+
+class B extends A {
+  const B() : super();
+}

tests/language/const_functions/const_functions_const_ctor_test.dart

@@ -0,0 +1,34 @@
+// 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.
+
+// Tests const constructors with a body which are enabled with const functions.
+
+// SharedOptions=--enable-experiment=const-functions
+
+import "package:expect/expect.dart";
+
+const printString = "print";
+const var1 = Simple(printString);
+class Simple {
+  final String name;
+
+  const Simple(this.name) {
+//                        ^
+// [analyzer] SYNTACTIC_ERROR.CONST_CONSTRUCTOR_WITH_BODY
+    assert(this.name == printString);
+  }
+}
+
+const var2 = A();
+class A {
+  const A() {
+  //        ^
+  // [analyzer] SYNTACTIC_ERROR.CONST_CONSTRUCTOR_WITH_BODY
+    return;
+  }
+}
+
+void main() {
+  Expect.equals(var1.name, printString);
+}