rb_econv_memsize 1429 internal.h     size_t rb_econv_memsize(rb_econv_t *);
rb_econv_memsize 4339 io.c               if (fptr->readconv) size += rb_econv_memsize(fptr->readconv);
rb_econv_memsize 4340 io.c               if (fptr->writeconv) size += rb_econv_memsize(fptr->writeconv);