Merge pull request #69 from SimonSapin/overflow

Upgrade to rustc 1.0.0-nightly (fed12499e 2015-03-03) (built 2015-03-04)

Author: alexcrichton

src/json.rs

@@ -1481,7 +1481,6 @@ impl<T: Iterator<Item = char>> Parser<T> {
 
     fn parse_u64(&mut self) -> Result<u64, ParserError> {
         let mut accum = 0;
-        let last_accum = 0; // necessary to detect overflow.
 
         match self.ch_or_null() {
             '0' => {
@@ -1497,11 +1496,16 @@ impl<T: Iterator<Item = char>> Parser<T> {
                 while !self.eof() {
                     match self.ch_or_null() {
                         c @ '0' ... '9' => {
-                            accum *= 10;
-                            accum += (c as u64) - ('0' as u64);
-
-                            // Detect overflow by comparing to the last value.
-                            if accum <= last_accum { return self.error(InvalidNumber); }
+                            macro_rules! try_or_invalid {
+                                ($e: expr) => {
+                                    match $e {
+                                        Some(v) => v,
+                                        None => return self.error(InvalidNumber)
+                                    }
+                                }
+                            }
+                            accum = try_or_invalid!(accum.checked_mul(10));
+                            accum = try_or_invalid!(accum.checked_add((c as u64) - ('0' as u64)));
 
                             self.bump();
                         }
@@ -1581,7 +1585,7 @@ impl<T: Iterator<Item = char>> Parser<T> {
 
     fn decode_hex_escape(&mut self) -> Result<u16, ParserError> {
         let mut i = 0;
-        let mut n = 016;
+        let mut n = 0;
         while i < 4 && !self.eof() {
             self.bump();
             n = match self.ch_or_null() {
@@ -2870,6 +2874,7 @@ mod tests {
         assert_eq!(Json::from_str("1e+"), Err(SyntaxError(InvalidNumber, 1, 4)));
 
         assert_eq!(Json::from_str("18446744073709551616"), Err(SyntaxError(InvalidNumber, 1, 20)));
+        assert_eq!(Json::from_str("18446744073709551617"), Err(SyntaxError(InvalidNumber, 1, 20)));
         assert_eq!(Json::from_str("-9223372036854775809"), Err(SyntaxError(InvalidNumber, 1, 21)));
 
         assert_eq!(Json::from_str("3"), Ok(U64(3)));