commit 846e91034f89821da1a59d4d4dd0eb77dc959e84
author ReticentIris <737959+ReticentIris@users.noreply.github.com> Mon Mar 18 20:40:36 2024 -0700
committer GitHub <noreply@github.com> Tue Mar 19 03:40:36 2024 +0000
tree f21fbae6677d6f3f76b0c51d432b89239de7622e
parent 5c6a402e1657e7161604689a16e1195b1a7335f2

Stop rustfmt versioning from overriding rust-analyzer versioning. (#2553)

There is a bug/typo in `rust_register_toolchains` where
`rustfmt_version` would always override `rust_analyzer_version` (default
or otherwise specified). This causes problems related to mismatched ABIs
when rust-analyzer tries to expand proc macros if one were to use an
older-than-default nightly toolchain without specifying a specific
`rustfmt_version`. This is because `rust-analyzer` will be set to use
the default `rustfmt_version` which is `nightly/2024-02-08`:
https://github.com/bazelbuild/rules_rust/blob/8b977b5f7020fc3a3b3bbc318e414269014f126a/rust/private/common.bzl#L36

As a very basic example of what I mean:
```
rust_register_toolchains(
    edition = "2021",
    versions = [
        "nightly/2024-01-31",
    ],
    extra_exec_rustc_flags = ["-A", "async_fn_in_trait"],
)
```
Will result in rust-analyzer complaining with:
```
proc macro `Deserialize` not expanded: Cannot create expander for /private/var/tmp/_bazel_a/a03e1cfb3989a3cda645602bbe0ee892/execroot/_main/bazel-out/darwin_arm64-opt-exec-ST-13d3ddad9198/bin/external/crate_index__serde_derive-1.0.195/libserde_derive-1365269244.dylib: mismatched ABI expected: `rustc 1.78.0-nightly (8ace7ea1f 2024-02-07)`, got `rustc 1.77.0-nightly (11f32b73e 2024-01-31)`rust-analyzer[unresolved-proc-macro](https://rust-analyzer.github.io/manual.html#unresolved-proc-macro)
```
Using a workaround of setting `rustfmt_version` causes the ABI mismatch
to be resolved:
```
rust_register_toolchains(
    edition = "2021",
    versions = [
        "nightly/2024-01-31",
    ],
    rustfmt_version = "nightly/2024-01-31",
    extra_exec_rustc_flags = ["-A", "async_fn_in_trait"],
)
```
This PR fixes the issue so that rust-analyzer version selection actually
works.

Co-authored-by: UebelAndre <github@uebelandre.com>