Build information dumping with --dump-build-info

[SuperAuguste]

Another one 😎

• Dependency (.dependency) information
• Build-level module information
• Step information
  • Name and structure
  • Modules
  • Options?

[marler8997]

Here was my previous feeble attempt in case it's helpful for reference: #9973

[rohlem]

Naming nit: While wet is indeed an antonym to dry, I don't think I've ever seen it in a CLI interface.
dry seems to stem primarily from dry run (i.e. practice/rehearsal), while the collocation wet run (for actual execution/competition/performance) isn't as actively used (or at all).

I'd suggest instead calling it on, as the antonym for the option off, as really, dry is its own separate category - the other two options don't influence build execution at all.
And calling them wet-on/wet-off or do-on/do-off is overkill as well; they're non-dry simply because if they were dry it'd be in their name.

[matklad]

Might be a stepping stone for #14286, "build graph for IDEs" ideally is the same thing as "build graph driving the execution of the build".

[andrewrk]

I suggest to create and use an API like this: https://github.com/ziglang/zig/blob/master/lib/std/json/write_stream.zig

This is a yak worth shaving IMO

[andrewrk]

Also just a word of caution... I can feel myself having a lot of opinions about the way this works. So if you have anything else to work on, you might want to prioritize that. I don't want you to do a bunch of work and then have the PR rot because I want to participate it in personally, but busy with other things.