Generally, the answer to such questions should be found in the manual:
Admittedly, it is far from perfect, so please send PRs with improvements
Specific bits relevant here:
- you can enable proc-macro support:
procMacro = { enable = true },
- you can disable this specific diagnostic:
diagnostics = { disabled = ["unresolved-proc-macro"] }
I've send https://github.com/rust-analyzer/rust-analyzer/pull/7012 to clarify how to verify that rust-analyzer is using the right config.