Set default for Encoding.default_external to UTF-8 on Windows (#2877)

* Use UTF-8 as default for Encoding.default_external on Windows
* Document UTF-8 change on Windows to Encoding.default_external

fix https://bugs.ruby-lang.org/issues/16604

1 files changed, 5 insertions, 2 deletions

diff --git a/ruby.c b/ruby.c
index 2ddea6b430..c01d78ef7e 100644
--- a/ruby.c
+++ b/ruby.c
@@ -1819,6 +1819,9 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
     Init_ruby_description();
     Init_enc();
     lenc = rb_locale_encoding();
+#if UTF8_PATH
+    uenc = rb_utf8_encoding();
+#endif
     rb_enc_associate(rb_progname, lenc);
     rb_obj_freeze(rb_progname);
     parser = rb_parser_new();
@@ -1839,7 +1842,7 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
 	enc = rb_enc_from_index(opt->ext.enc.index);
     }
     else {
-	enc = lenc;
+	enc = IF_UTF8_PATH(uenc, lenc);
     }
     rb_enc_set_default_external(rb_enc_from_encoding(enc));
     if (opt->intern.enc.index >= 0) {
@@ -1944,7 +1947,7 @@ process_options(int argc, char **argv, ruby_cmdline_options_t *opt)
 	enc = rb_enc_from_index(opt->ext.enc.index);
     }
     else {
-	enc = lenc;
+	enc = IF_UTF8_PATH(uenc, lenc);
     }
     rb_enc_set_default_external(rb_enc_from_encoding(enc));
     if (opt->intern.enc.index >= 0) {