Issue 29358. Fix for reporting constant errors while evaluating constructor invocations.

pkg/analyzer/lib/src/error/codes.dart

 // Copyright (c) 2014, 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.
 
 library analyzer.src.error.codes;
 
 import 'package:analyzer/error/error.dart';
 
 export 'package:analyzer/src/analysis_options/error/option_codes.dart';
 export 'package:analyzer/src/dart/error/hint_codes.dart';
@@ skipping 33 matching lines @@
    * object results in an uncaught exception being thrown.
    */
   static const CheckedModeCompileTimeErrorCode
       CONST_CONSTRUCTOR_PARAM_TYPE_MISMATCH =
       const CheckedModeCompileTimeErrorCode(
           'CONST_CONSTRUCTOR_PARAM_TYPE_MISMATCH',
           "A value of type '{0}' can't be assigned to a parameter of type "
           "'{1}'.");
 
   /**
+   * 16.12.2 Const: It is a compile-time error if evaluation of a constant
+   * object results in an uncaught exception being thrown.
+   */
+  static const CheckedModeCompileTimeErrorCode CONST_EVAL_THROWS_EXCEPTION =
+      const CheckedModeCompileTimeErrorCode('CONST_EVAL_THROWS_EXCEPTION',
+          "Evaluation of this constant expression throws an exception.");

[Brian Wilkerson, 2017/04/18 18:53:21]

I can't see, from the tests, where the error is being reported, so it might not
be as bad as I'm imagining, but this seems vague. Longer term (not for this CL),
is there any reasonable way for us to give more actionable feedback (don't pass
this value for this argument) or more compete information (such as where the
exception will be thrown).

[scheglov, 2017/04/18 19:11:03]

Potentially it would be a sequence of places, and/or several reasons at several
places.

For example:

class A {
  const A() : v = new Object();
  final v;
}

class B {
  const B() : a = const A();
  final a;
}

class C {
  const C() : b = const B();
  final b;
}

const c = const C();

We will report an error for the top-level variable "c".
The actual problem is however in A (new Object() instead of const Object()).
Not quite this error code, but I think you get the idea.

+
+  /**
    * 7.6.1 Generative Constructors: In checked mode, it is a dynamic type error
    * if o is not <b>null</b> and the interface of the class of <i>o</i> is not a
    * subtype of the static type of the field <i>v</i>.
    *
    * 16.12.2 Const: It is a compile-time error if evaluation of a constant
    * object results in an uncaught exception being thrown.
    *
    * Parameters:
    * 0: the name of the type of the initializer expression
    * 1: the name of the type of the field
@@ skipping 4990 matching lines @@
    * created from the optional [correction] template.
    */
   const StrongModeCode(ErrorType type, String name, String message,
       [String correction])
       : type = type,
         super('STRONG_MODE_$name', message, correction);
 
   @override
   ErrorSeverity get errorSeverity => type.severity;
 }