Can't get rust-analyzer to work in vscode within the rust repository

Following https://rustc-dev-guide.rust-lang.org/building/suggested.html I can't get rust-analyzer to run x.py check on save

Running x.py manually works fine

I'm on the current tip of master branch, commit https://github.com/rust-lang/rust/tree/90782cb50ba6d1f2ea97cf74a3b06eca6bef8b59

The error seems to be

Method: rust-analyzer/analyzerStatus
 error: invalid type: sequence, expected unit', /rustc/04488afe34512aa4c33566eb16d8c912a3ae04f9\src\libstd\macros.rs:16:9

I wasn't allowed to post more than two links so here are my logs:

server output: https://hatebin.com/vqgqjgwfki
client output: https://hatebin.com/nsiucvwqjr

These logs are using the nightly option, I got a similar thing using stable

I haven't managed to figure out how to set RUST_BACKTRACE for the extension