Feature request: Open docs for symbol should support locally built documentation

[crumblingstatue]

Rust-analyzer has a feature to open the docs for the symbol under the cursor, but it always uses docs.rs.
One could be using different versions of crates that aren't on docs.rs, like git dependencies, and also your local crate(s) aren't on docs.rs either.

Open docs should do a best-effort detection of locally built documentation (usually $TARGET_DIR/doc), and open that if the symbol is available under that, before falling back to docs.rs.

[Ddystopia]

Should it generate latest docs if they are not up to date?

[crumblingstatue]

That's a good question. Would there be any drawbacks to that behavior?
But I think this can be implemented later, and for now it could just detect whether local documentation exists and use it if available.

[lnicola]

Reopening because #14662 didn't add the client support for Code.