pub const Tag = enum(u32) {
    /// Tells the compiler to shut down cleanly.
    /// No body.
    exit,
    /// Tells the compiler to detect changes in source files and update the
    /// affected output compilation artifacts.
    /// If one of the compilation artifacts is an executable that is
    /// running as a child process, the compiler will wait for it to exit
    /// before performing the update.
    /// No body.
    update,
    /// Tells the compiler to execute the executable as a child process.
    /// No body.
    run,
    /// Tells the compiler to detect changes in source files and update the
    /// affected output compilation artifacts.
    /// If one of the compilation artifacts is an executable that is
    /// running as a child process, the compiler will perform a hot code
    /// swap.
    /// No body.
    hot_update,
    /// Ask the test runner for metadata about all the unit tests that can
    /// be run. Server will respond with a `test_metadata` message.
    /// No body.
    query_test_metadata,
    /// Ask the test runner to run a particular test.
    /// The message body is a u32 test index.
    run_test,
    /// Ask the test runner to start fuzzing a particular test.
    /// The message body is a u32 test index.
    start_fuzzing,

    _,
}