rb_econv_check_error 2234 ext/zlib/zlib.c         rb_econv_check_error(gz->ec);
rb_econv_check_error  249 include/ruby/encoding.h void rb_econv_check_error(rb_econv_t *ec);
rb_econv_check_error 1565 io.c                   rb_econv_check_error(fptr->readconv);
rb_econv_check_error 1584 io.c                               rb_econv_check_error(fptr->readconv);
rb_econv_check_error 1760 transcode.c            rb_econv_check_error(ec);