[Pitch] Improved Compiler Error Messages

[xwu (Xiaodi Wu)]

Quality of implementation improvements to diagnostics are not subject to Swift Evolution. You may be interested in prior work in this area:

Update on experimental diagnostics features

A brief update: I'm happy to announce that most of the educational notes infrastructure has now landed on master, and the feature is now enabled by default! As a result, the hidden frontend flag enable-educational-notes has been removed. Notes can be shown on the command line by passing the new -print-educational-notes flag. I've also created a jira task to track expanding coverage to more diagnostics, and added a quick-start guide which assumes no prior knowledge or contributions if anyone is…