9752: feature: Declare proc-macro dependent crates in `rust-project.json` r=matklad a=tobywf
This adds the `is_proc_macro` flag in `rust-project.json`. By default, this is `false` and not required, so existing projects won't break/have the same behavior as before this change. If the flag is true, a dependency to the `proc_macro` sysroot crate is added (if it exists), so that rust-analyzer can resolve those imports.
This fixes#9726 .
I've also added some tests in the second commit. The first is a smoke test for a basic, minimal `rust-project.json` file. The second is a more targeted test for the flag. Both tests depend on the fake sysroot (a bunch of directories in the correct layout with empty `lib.rs` files), and also on `env!("CARGO_MANIFEST_DIR")` being an absolute path. I'm not sure if the later assumption is valid on all platforms. I wanted to at least try and add tests, but I'm happy to rework them or remove them if you don't think that's the way to go.
(You can license/relicense my contribution in any way you wish without contacting me.)
Co-authored-by: Toby Fleming <sourcecode@tobywf.com>
Being new to Rust I wasn't familiar with this acronym and found it hard to guess (the context of syntax trees biased me to reading it as a D-something Syntax Tree and trying to guess what the D was), hard to google (in retrospect googling "rust dst" does the job, but I thought it was an abstract structure thing, not Rust-specific), and hard to Github-search, because `dst` is commonly short for “destination” in code.
Alternatively `<abbr title="dynamically sized type">DST</abbr>` would be about as helpful.
Some features of rust-analyzer requires support for custom commands on
the client side. Specifically, hover & code lens need this.
Stock LSP doesn't have a way for the server to know which client-side
commands are available. For that reason, we historically were just
sending the commands, not worrying whether the client supports then or
not.
That's not really great though, so in this PR we add infrastructure for
the client to explicitly opt-into custom commands, via `extensions`
field of the ClientCapabilities.
To preserve backwards compatability, if the client doesn't set the
field, we assume that it does support all custom commands. In the
future, we'll start treating that case as if the client doesn't support
commands.
So, if you maintain a rust-analyzer client and implement
`rust-analyzer/runSingle` and such, please also advertise this via a
capability.
