* error.c (syserr_initialize): use mesg's encoding when locale

  encoding is US-ASCII. If locale encoding is not US-ASCII,
  assume err has non ASCII characters. [ruby-dev:42358]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@29439 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 8 insertions, 1 deletions

diff --git a/error.c b/error.c
index f05600f7fb..94126f709b 100644
--- a/error.c
+++ b/error.c
@@ -1048,16 +1048,23 @@ syserr_initialize(int argc, VALUE *argv, VALUE self)
     if (!NIL_P(error)) err = strerror(NUM2INT(error));
     else err = "unknown error";
     if (!NIL_P(mesg)) {
+	rb_encoding *le = rb_locale_encoding();
 	VALUE str = mesg;
 
 	StringValue(str);
 	mesg = rb_sprintf("%s - %.*s", err,
 			  (int)RSTRING_LEN(str), RSTRING_PTR(str));
+	if (le == rb_usascii_encoding()) {
+	    rb_encoding *me = rb_enc_get(mesg);
+	    if (le != me && rb_enc_asciicompat(me))
+		le = me;
+	}/* else assume err is non ASCII string. */
+	rb_enc_associate(mesg, le);
     }
     else {
 	mesg = rb_str_new2(err);
+	rb_enc_associate(mesg, rb_locale_encoding());
     }
-    rb_enc_associate(mesg, rb_locale_encoding());
     rb_call_super(1, &mesg);
     rb_iv_set(self, "errno", error);
     return self;