auto merge of #4747 : sanxiyn/rust/integral-type, r=graydon

`ty::type_is_integral` returns `true` for `ty_bool`. This causes `-true` to compile, instead of resulting in a type error.

src/librustc/middle/ty.rs

@@ -2435,7 +2435,7 @@ pub fn type_structurally_contains_uniques(cx: ctxt, ty: t) -> bool {
 
 pub fn type_is_integral(ty: t) -> bool {
     match get(ty).sty {
-      ty_infer(IntVar(_)) | ty_int(_) | ty_uint(_) | ty_bool => true,
+      ty_infer(IntVar(_)) | ty_int(_) | ty_uint(_) => true,
       _ => false
     }
 }

src/test/compile-fail/unop-neg-bool.rs

@@ -0,0 +1,3 @@
+fn main() {
+    -true; //~ ERROR cannot apply unary operator `-` to type `bool`
+}