fn check_error_format_stability(
early_dcx: &EarlyDiagCtxt,
unstable_opts: &UnstableOptions,
is_nightly_build: bool,
format: ErrorOutputType,
)fn check_error_format_stability(
early_dcx: &EarlyDiagCtxt,
unstable_opts: &UnstableOptions,
is_nightly_build: bool,
format: ErrorOutputType,
)