rb_econv_has_convpath_p  303 include/ruby/encoding.h int rb_econv_has_convpath_p(const char* from_encoding, const char* to_encoding);
rb_econv_has_convpath_p 7061 win32/win32.c  	if (!rb_econv_has_convpath_p(rb_enc_name(rb_enc_from_index(encindex)), "UTF-8"))