Fix int::parse_buf for negative numbers (#1102)

src/lib/int.rs

@@ -103,16 +103,18 @@ fn parse_buf(buf: [u8], radix: uint) -> int {
         fail;
     }
     let i = vec::len::<u8>(buf) - 1u;
+    let start = 0u;
     let power = 1;
+
     if buf[0] == ('-' as u8) {
         power = -1;
-        i -= 1u;
+        start = 1u;
     }
     let n = 0;
     while true {
         n += (buf[i] - ('0' as u8) as int) * power;
         power *= radix as int;
-        if i == 0u { ret n; }
+        if i <= start { ret n; }
         i -= 1u;
     }
     fail;

src/test/stdtest/int.rs

@@ -3,6 +3,21 @@
 import std::int;
 import std::str::eq;
 
+#[test]
+fn test_from_str() {
+    assert(int::from_str("0") == 0);
+    assert(int::from_str("3") == 3);
+    assert(int::from_str("10") == 10);
+    assert(int::from_str("123456789") == 123456789);
+    assert(int::from_str("00100") == 100);
+
+    assert(int::from_str("-1") == -1);
+    assert(int::from_str("-3") == -3);
+    assert(int::from_str("-10") == -10);
+    assert(int::from_str("-123456789") == -123456789);
+    assert(int::from_str("-00100") == -100);
+}
+
 #[test]
 fn test_to_str() {
     assert (eq(int::to_str(0, 10u), "0"));
@@ -29,4 +44,4 @@ fn test_overflows() {
    assert (int::max_value() > 0);
    assert (int::min_value() <= 0);
    assert (int::min_value() + int::max_value() + 1 == 0);
-}
+}