class Aws::S3::Plugins::ARN

def validate_region_config!(arn, region, use_arn_region)
  if ['s3-external-1', 'aws-global'].include?(region)
    # These "regions" are not regional endpoints
    unless use_arn_region
      raise Aws::Errors::InvalidARNRegionError,
            'Configured client region is not a regional endpoint.'
    end
    # These "regions" are in the AWS partition
    # Cannot use ARN region unless it's the same partition
    unless arn.partition == 'aws'
      raise Aws::Errors::InvalidARNPartitionError
    end
  else
    if region.include?('fips')
      # If ARN type doesn't support FIPS but the client region is FIPS
      unless arn.support_fips?
        raise ArgumentError,
              'FIPS client regions are not supported for this type '\
              'of ARN.'
      end
      fips = true
      # Normalize the region so we can compare partition and regions
      region = region.gsub('fips-', '').gsub('-fips', '')
    end
    # Raise if the ARN and client regions are in different partitions
    if use_arn_region &&
       !Aws::Partitions.partition(arn.partition).region?(region)
      raise Aws::Errors::InvalidARNPartitionError
    end
    # Raise if regions mismatch
    # Either when it's a fips client or not using the ARN region
    if (!use_arn_region || fips) && region != arn.region
      raise Aws::Errors::InvalidARNRegionError
    end
  end
end