Hermetic vs system rust-analyzer.

[lromor]

Hi,

The rules work really well! Thanks a lot for your work.
I have a question, what do you suggest to have the editor pick the right rust-analyzer? I'm using nix and I'm noticing some errors when using the system/flake version vs the hermetic one.

No error when using (rust-analyzer 1.86.0 (05f9846 2025-03-31)):

rules_rust++rust+rust_analyzer_1.86.0_tools/bin/rust-analyzer diagnostics .

Error when using the system one (rust-analyzer 2025-10-28):

ERROR `cargo metadata` failed on `/home/<...>/.cache/bazel/<...>/e2e3cb9bf16f1c81675a0d2877a06ae9/external/rules_rust++rust+rust_analyzer_1.86.0_tools/lib/rustlib/src/library/Cargo.toml` : Failed to run `cd "/home/<...>/.cache/bazel/<...>/e2e3cb9bf16f1c81675a0d2877a06ae9/external/rules_rust++rust+rust_analyzer_1.86.0_tools/lib/rustlib/src/library" && RUSTUP_AUTO_INSTALL="0" RUSTUP_TOOLCHAIN="/home/<...>/.cache/bazel/<...>/e2e3cb9bf16f1c81675a0d2877a06ae9/external/rules_rust++rust+rust_analyzer_1.86.0_tools" __CARGO_TEST_CHANNEL_OVERRIDE_DO_NOT_USE_THIS="nightly" "cargo" "metadata" "--format-version" "1" "--manifest-path" "/home/lromor/.cache/bazel/_bazel_lromor/e2e3cb9bf16f1c81675a0d2877a06ae9/external/rules_rust++rust+rust_analyzer_1.86.0_tools/lib/rustlib/src/library/Cargo.toml" "--filter-platform" "x86_64-unknown-linux-gnu" "--lockfile-path" "/tmp/rust-analyzerb7ad-0/Cargo.lock" "-Zunstable-options"`

I see the following options:

1. Add a config and a repo rule that configures the toolchains to either use the local version of rust-analyzer or the hermetic one.
2. Tell the IDE (emacs) to use the hermetic version of rust-analyzer.

What would be your goto solution? Do you have any other in mind?