One shared guide for diagnostics.

pkg/front_end/lib/src/base/errors.dart

Index: pkg/front_end/lib/src/base/errors.dart
diff --git a/pkg/front_end/lib/src/base/errors.dart b/pkg/front_end/lib/src/base/errors.dart
index d39953f50ab0739f94f9af899f302bc8c914e4ff..2f9884a9db6d99fdef0b5173745b543ea3a0739c 100644
--- a/pkg/front_end/lib/src/base/errors.dart
+++ b/pkg/front_end/lib/src/base/errors.dart
@@ -2,65 +2,10 @@
 // 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.
 
-/**
- * An error code associated with an [AnalysisError].
- *
- * Generally, we want to provide messages that consist of three sentences. From
- * the user's perspective these sentences should explain:
- *
- * 1. what is wrong,
- * 2. why is it wrong, and
- * 3. how do I fix it.
- *
- * However, we combine the first two in the [message] and the last in the
- * [correction].
- *
- * When composing messages (including correction messages) keep the following
- * guidelines in mind.
- *
- * 1. The message should be a complete sentence starting with an uppercase
- * letter, and ending with a period.
- *
- * 2. Reserved words and embedded identifiers should be in single quotes, so
- * prefer double quotes for the complete message. For example,
- * ```
- * "The class '{0}' can't use 'super'."
- * ```
- * Notice that the word 'class' in the preceding message is not quoted as it
- * refers to the concept 'class', not the reserved word. On the other hand,
- * 'super' refers to the reserved word. Do not quote 'null' and numeric literals.
- *
- * 3. Do not try to compose messages, as it can make translating them hard.
- *
- * 4. Try to keep the error messages short, but informative.
- *
- * 5. Use simple words and terminology, assume the reader of the message doesn't
- * have an advanced degree in math, and that English is not the reader's native
- * language. Do not assume any formal computer science training. For example, do
- * not use Latin abbreviations (prefer "that is" over "i.e.", and "for example"
- * over "e.g."). Also avoid phrases such as "if and only if" and "iff"; that
- * level of precision is unnecessary.
- *
- * 6. Prefer contractions when they are in common use, for example, prefer
- * "can't" over "cannot". Using "cannot", "must not", "shall not", etc. is
- * off-putting to people new to programming.
- *
- * 7. Use common terminology, preferably from the Dart Language Specification.
- * This increases the user's chance of finding a good explanation on the web.
- *
- * 8. Do not try to be cute or funny. It is extremely frustrating to work on a
- * product that crashes with a "tongue-in-cheek" message, especially if you did
- * not want to use this product to begin with.
- *
- * 9. Do not lie, that is, do not write error messages containing phrases like
- * "can't happen".  If the user ever saw this message, it would be a lie. Prefer
- * messages like: "Internal error: This function should not be called when 'x'
- * is null.".
- *
- * 10. Prefer to not use the imperative tone. That is, the message should not
- * sound accusing or like it is ordering the user around. The computer should
- * describe the problem, not criticize the user for violating the specification.
- */
+/// An error code associated with an [AnalysisError].
+///
+/// Generally, messages should follow the [Guide for Writing
+/// Diagnostics](../fasta/diagnostics.md).
 abstract class ErrorCode {
   /**
    * The name of the error code.