rollup merge of #20593: nikomatsakis/unused-tps-in-impl

Conflicts:
	src/libcollections/lib.rs
	src/librustc/lib.rs
	src/libserialize/lib.rs
	src/libstd/lib.rs

src/libsyntax/ast.rs

@@ -979,8 +979,8 @@ pub enum Sign {
     Plus
 }
 
-impl<T> Sign where T: Int {
-    pub fn new(n: T) -> Sign {
+impl Sign {
+    pub fn new<T:Int>(n: T) -> Sign {
         if n < Int::zero() {
             Minus
         } else {