bazel: Can't compile java with java toolchains for the host platform with remote execution enabled

I’m trying to switch a repo to use --incompatible_use_toolchain_resolution_for_java_rules. I’m running into issues with the interplay with remote execution, and building either with the default --platforms, or when running bazel run. When building without remote execution, my toolchains are working properly.

My goal is for the host machine to be used for compiles which are both exec_compatible_with and target_compatible_with the host platform, if the remote execution system doesn’t support such a platform.

I am also using a C++ toolchain with --incompatible_enable_cc_toolchain_resolution - this works fine already.

My set up:

• Running on a Mac.
• Remote execution cluster which supports Linux execution (requiring a particular platform properties), but which does not support Mac execution. Bazel has one --extra_execution_platforms registered which points at the Linux platform properties. I’ve also tried adding @bazel_tools//platforms:host_platform as an --extra_execution_platforms to no avail.
• Both a Linux and Mac JDK are registered using register_toolchains - these have exec_compatible_with set to ["@platforms//os:macos"] or ["@platforms//os:linux"].
• Running bazel build //some/java:binary --remote_executor=redacted or bazel run //some/java:binary --remote_executor=redacted or bazel build //some/java:binary --remote_executor=redacted --platforms=@bazel_tools//platforms:host_platform

I’ve tried using bazel 4.0.0 and bazel at 3733065ddd418357e0e74091789ace5884b01fef.

Here’s what I see in each combination of flags:

$ bazel build //some/java:binary --remote_executor=redacted --extra_execution_platforms=//my/remote/linux:platform

Attempts to run javac with a Linux JDK on the remote execution system with no platform properties set, and so complains that the remote execution platform doesn’t support macOS (though note: it is including a Linux JDK as inputs to the action). The same result happens when also adding ,@bazel_tools//platforms:host_platform to --extra_execution_platforms.

$ bazel build //some/java:binary --remote_executor=redacted --extra_execution_platforms=//my/remote/linux:platform --platforms=@bazel_tools//platforms:host_platform

Errors because it claims that the C++ toolchain mismatches with the platform on values osx, x86_64 even though it is defined as:

    exec_compatible_with = [ 
        "@platforms//cpu:x86_64",
        "@platforms//os:osx",
    ],  
    target_compatible_with = [ 
        "@platforms//os:osx",
        "@platforms//cpu:x86_64",
    ],