Prohibit parenthesized params in more types.

src/test/compile-fail/issue-32995.rs

@@ -0,0 +1,25 @@
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    let s: String() = String::from("foo");
+    //~^ ERROR parenthesized parameters may only be used with a trait
+
+    let x: usize() = 1;
+    //~^ ERROR parenthesized parameters may only be used with a trait
+
+    let b: ::std::boxed()::Box<_> = Box::new(1);
+    //~^ ERROR parenthesized parameters may only be used with a trait
+}
+
+fn foo<X:Default>() {
+    let d : X() = Default::default();
+    //~^ ERROR parenthesized parameters may only be used with a trait
+}