libstd: remove unnecessary to_string() calls

src/libstd/num/strconv.rs

@@ -428,28 +428,28 @@ mod tests {
     #[test]
     fn test_int_to_str_overflow() {
         let mut i8_val: i8 = 127_i8;
-        assert_eq!(i8_val.to_string(), "127".to_string());
+        assert_eq!(i8_val.to_string(), "127");
 
         i8_val += 1 as i8;
-        assert_eq!(i8_val.to_string(), "-128".to_string());
+        assert_eq!(i8_val.to_string(), "-128");
 
         let mut i16_val: i16 = 32_767_i16;
-        assert_eq!(i16_val.to_string(), "32767".to_string());
+        assert_eq!(i16_val.to_string(), "32767");
 
         i16_val += 1 as i16;
-        assert_eq!(i16_val.to_string(), "-32768".to_string());
+        assert_eq!(i16_val.to_string(), "-32768");
 
         let mut i32_val: i32 = 2_147_483_647_i32;
-        assert_eq!(i32_val.to_string(), "2147483647".to_string());
+        assert_eq!(i32_val.to_string(), "2147483647");
 
         i32_val += 1 as i32;
-        assert_eq!(i32_val.to_string(), "-2147483648".to_string());
+        assert_eq!(i32_val.to_string(), "-2147483648");
 
         let mut i64_val: i64 = 9_223_372_036_854_775_807_i64;
-        assert_eq!(i64_val.to_string(), "9223372036854775807".to_string());
+        assert_eq!(i64_val.to_string(), "9223372036854775807");
 
         i64_val += 1 as i64;
-        assert_eq!(i64_val.to_string(), "-9223372036854775808".to_string());
+        assert_eq!(i64_val.to_string(), "-9223372036854775808");
     }
 }
 

src/libstd/num/uint_macros.rs

@@ -79,28 +79,28 @@ mod tests {
     #[test]
     fn test_uint_to_str_overflow() {
         let mut u8_val: u8 = 255_u8;
-        assert_eq!(u8_val.to_string(), "255".to_string());
+        assert_eq!(u8_val.to_string(), "255");
 
         u8_val += 1 as u8;
-        assert_eq!(u8_val.to_string(), "0".to_string());
+        assert_eq!(u8_val.to_string(), "0");
 
         let mut u16_val: u16 = 65_535_u16;
-        assert_eq!(u16_val.to_string(), "65535".to_string());
+        assert_eq!(u16_val.to_string(), "65535");
 
         u16_val += 1 as u16;
-        assert_eq!(u16_val.to_string(), "0".to_string());
+        assert_eq!(u16_val.to_string(), "0");
 
         let mut u32_val: u32 = 4_294_967_295_u32;
-        assert_eq!(u32_val.to_string(), "4294967295".to_string());
+        assert_eq!(u32_val.to_string(), "4294967295");
 
         u32_val += 1 as u32;
-        assert_eq!(u32_val.to_string(), "0".to_string());
+        assert_eq!(u32_val.to_string(), "0");
 
         let mut u64_val: u64 = 18_446_744_073_709_551_615_u64;
-        assert_eq!(u64_val.to_string(), "18446744073709551615".to_string());
+        assert_eq!(u64_val.to_string(), "18446744073709551615");
 
         u64_val += 1 as u64;
-        assert_eq!(u64_val.to_string(), "0".to_string());
+        assert_eq!(u64_val.to_string(), "0");
     }
 
     #[test]