Fix the parsing of where-clauses for structs

src/test/run-pass/issue-17904.rs

@@ -0,0 +1,22 @@
+// Copyright 2014 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.
+
+// Tests that type assignability is used to search for instances when
+// making method calls, but only if there aren't any matches without
+// it.
+
+struct Foo<T> where T: Copy;
+struct Bar<T>(T) where T: Copy;
+struct Bleh<T, U>(T, U) where T: Copy, U: Sized;
+struct Baz<T> where T: Copy {
+    field: T
+}
+
+fn main() {}