`rust-toolchain.toml` is too old for the current proc-macros protocol
(specifically, the `--keep-going` flag was not stable in Rust 1.70, as
can be verified by `cargo +1.70.0 check --keep-going`).
This works around https://github.com/rust-lang/rust-analyzer/issues/17662 ,
and very likely future problems, because the rust-analyzer devs are quite
aggressive in depending on recent versions: "by policy we don't make any
attempts at supporting more than the last couple of stable releases"
according to https://github.com/rust-lang/rust-analyzer/issues/17662#issuecomment-2242265513 .
The toolchain we select in `rust-toolchain.toml` often lags behind that
intentionally, because we want to verify that we build with our MSRV.
Signed-off-by: Daira-Emma Hopwood <daira@jacaranda.org>
This setting is no longer required, and its presence greatly increases build and test times while using VS Code extensions for rust because inconsistent settings are used, defeating the rust build cache.
Daira-Emma Hopwood
Andrew Arnott
Jack Grigg