Don't prepend anything when gb18030 range decode fails per whatwg/encoding#110.

Author: hsivonen

README.md

@@ -96,6 +96,11 @@ encoding_rs is
 
 ## Release Notes
 
+### 0.6.9
+
+* [Don't prepend anything when gb18030 range decode
+  fails](https://github.com/whatwg/encoding/issues/110). (Spec change.)
+
 ### 0.6.8
 
 * Correcly handle the case where the first buffer contains potentially

src/gb18030.rs

@@ -267,10 +267,8 @@ impl Gb18030Decoder {
                 // Astral
                 handle.write_astral((pointer - (189000usize - 0x10000usize)) as u32)
             } else {
-                self.pending_ascii = Some(second_minus_offset + 0x30);
-                self.pending = Gb18030Pending::One(third_minus_offset);
-                return (DecoderResult::Malformed(1, 2),
-                        unread_handle_fourth.unread(),
+                return (DecoderResult::Malformed(4, 0),
+                        unread_handle_fourth.consumed(),
                         handle.written());
             }
         },
@@ -598,11 +596,8 @@ mod tests {
         decode_gb18030(b"\x81\x37\xA3\x30", "\u{2603}");
         decode_gb18030(b"\x94\x39\xDA\x33", "\u{1F4A9}");
         decode_gb18030(b"\xE3\x32\x9A\x35", "\u{10FFFF}");
-        decode_gb18030(b"\xE3\x32\x9A\x36\x81\x30", "\u{FFFD}\u{0032}\u{309B8}");
-        decode_gb18030(
-            b"\xE3\x32\x9A\x36\x81\x40",
-            "\u{FFFD}\u{0032}\u{FFFD}\u{0036}\u{4E02}",
-        );
+        decode_gb18030(b"\xE3\x32\x9A\x36\x81\x30", "\u{FFFD}\u{FFFD}");
+        decode_gb18030(b"\xE3\x32\x9A\x36\x81\x40", "\u{FFFD}\u{4E02}");
         decode_gb18030(b"\xE3\x32\x9A", "\u{FFFD}"); // not \u{FFFD}\u{0032}\u{FFFD} !
 
     }

src/lib.rs

@@ -2920,10 +2920,9 @@ pub enum DecoderResult {
     /// the malformed sequence. Note that the malformed bytes may have been part
     /// of an earlier input buffer.
     ///
-    /// The first wrapped integer can have values 1, 2 or 3. The second
-    /// wrapped integer can have values 0, 1, 2 or 3. This makes the
-    /// worst-case sum of the two 6, and the worst case actually happens with
-    /// ISO-2022-JP.
+    /// The first wrapped integer can have values 1, 2, 3 or 4. The second
+    /// wrapped integer can have values 0, 1, 2 or 3. The worst-case sum
+    /// of the two is 6, which happens with ISO-2022-JP.
     Malformed(u8, u8), // u8 instead of usize to avoid useless bloat
 }