bazelbuild
Building with --@rules_rust//:error_format flag invalidates Bazel cache
Running bazel build <target> followed by bazel build --error-format=json <target> will discard analysis cache and action cache:
(from build command log)
INFO: Build option --@rules_rust//:error_format has changed, discarding analysis cache.
(From bazel explain log)
Executing action 'Compiling Rust (without process_wrapper) rlib tinyjson (4 files)': action command has changed.
New action: Compiling Rust (without process_wrapper) rlib tinyjson (4 files)
A consecutive bazel build <target> will run without action cache as well.
This behavior isn't really surprising, as described in several Bazel tickets - i.e https://github.com/bazelbuild/bazel/issues/13591 but as Cargo manages to re emit errors in json format without recompiling the project, I seek your advice.
In our use case we setup Rust analyzer to run a custom cargo check command that uses the --error-format=json flag. This results in consecutive builds with and without this flag. We edit code, Rust analyzer runs bazel build --error-format=json, than we run the tests without the --error-format=json flag. This results in a very cache inefficient workflow
