merge revision(s) r47716: [Backport #10285]

	* ext/stringio/stringio.c (strio_write): ASCII-8BIT StringIO
	  should be writable any encoding strings, without conversion.
	  [ruby-core:65240] [Bug #10285]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@47982 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 3 insertions, 2 deletions

diff --git a/ext/stringio/stringio.c b/ext/stringio/stringio.c
index 1a12d298e1..55563c3a69 100644
--- a/ext/stringio/stringio.c
+++ b/ext/stringio/stringio.c
@@ -1169,12 +1169,13 @@ strio_write(VALUE self, VALUE str)
     struct StringIO *ptr = writable(self);
     long len, olen;
     rb_encoding *enc, *enc2;
+    rb_encoding *const ascii8bit = rb_ascii8bit_encoding();
 
     if (!RB_TYPE_P(str, T_STRING))
 	str = rb_obj_as_string(str);
     enc = rb_enc_get(ptr->string);
     enc2 = rb_enc_get(str);
-    if (enc != enc2 && enc != rb_ascii8bit_encoding()) {
+    if (enc != enc2 && enc != ascii8bit) {
 	str = rb_str_conv_enc(str, enc2, enc);
     }
     len = RSTRING_LEN(str);
@@ -1185,7 +1186,7 @@ strio_write(VALUE self, VALUE str)
 	ptr->pos = olen;
     }
     if (ptr->pos == olen) {
-	if (enc2 == rb_ascii8bit_encoding()) {
+	if (enc == ascii8bit || enc2 == ascii8bit) {
 	    rb_enc_str_buf_cat(ptr->string, RSTRING_PTR(str), len, enc);
 	    OBJ_INFECT(ptr->string, str);
 	}