io.c: fix 7bit coderange condition

* io.c (io_getc): fix 7bit coderange condition, check if ascii read
  data instead of read length. [ruby-core:55444] [Bug #8516]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41250 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Wed Jun 12 12:44:45 2013  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* io.c (io_getc): fix 7bit coderange condition, check if ascii read
+	  data instead of read length. [ruby-core:55444] [Bug #8516]
+
 Wed Jun 12 12:35:13 2013  Tanaka Akira  <akr@fsij.org>
 
 	* pack.c (pack_pack): Use rb_integer_pack_2comp.

io.c

@@ -3411,7 +3411,11 @@ io_getc(rb_io_t *fptr, rb_encoding *enc)
 	}
 	else {
 	    io_shift_cbuf(fptr, MBCLEN_CHARFOUND_LEN(r), &str);
-	    cr = ISASCII(r) ? ENC_CODERANGE_7BIT : ENC_CODERANGE_VALID;
+	    cr = ENC_CODERANGE_VALID;
+	    if (MBCLEN_CHARFOUND_LEN(r) == 1 && rb_enc_asciicompat(read_enc) &&
+		ISASCII(RSTRING_PTR(str)[0])) {
+		cr = ENC_CODERANGE_7BIT;
+	    }
 	}
 	str = io_enc_str(str, fptr);
 	ENC_CODERANGE_SET(str, cr);

test/ruby/test_io_m17n.rb

@@ -2196,7 +2196,17 @@ EOT
       open("a", "wb") {|f| f.puts "a"}
       open("a", "rt") {|f| f.getc}
     }
-    assert(c.ascii_only?, "should be ascii_only #{bug4557}")
+    assert_predicate(c, :ascii_only?, bug4557)
+  end
+
+  def test_getc_conversion
+    bug8516 = '[ruby-core:55444] [Bug #8516]'
+    c = with_tmpdir {
+      open("a", "wb") {|f| f.putc "\xe1"}
+      open("a", "r:iso-8859-1:utf-8") {|f| f.getc}
+    }
+    assert_not_predicate(c, :ascii_only?, bug8516)
+    assert_equal(1, c.size, bug8516)
   end
 
   def test_default_mode_on_dosish