Beautiful printing for rustc --explain command

[GuillaumeGomez]

I open this issue to allow people to follow this feature status and I'd also like to do it myself if no one is against it.

This issue was "proposed" in #24523.

[tbelaire]

So, I think it'd look best with the markdown rule of blank line + 4 space indent denotes a code block, same as ``` does, and that is a cleaner fallback when printing it to the terminal I feel. Does that make sense?

[GuillaumeGomez]

You mean writing error explanation like this:

blabla
blabla

`` `
    code
    code
`` `

blabla

?

[tbelaire]

No, check it out, this is a code block

this is a code block.

Source:

No, check it out, this is a code block

    this is a code block.

[tbelaire]

Here's the spec for it: http://daringfireball.net/projects/markdown/syntax#precode

Technically, the ``` blocks are an extension to markdown, though they are pretty nice. It's easier to add in a plaintext editor, though the indent is easier in vim.

[steveklabnik]

Triage: I am not 100% sure what exactly is being proposed here; @jonathandturner has been working on a new error formatting RFC that may significantly modify --explain's output, though.

[Mark-Simulacrum]

This does not seem to be a concrete issue, so I'm not sure that we should keep it open. @GuillaumeGomez Could you maybe update the description with at least one or two things that we should do?

[GuillaumeGomez]

I think there's no point keeping it open now. People are working on this and it's on the roadmap iirc. Let's close it then.