Add tests to fixed issues.

Closes rust-lang#36792. Closes rust-lang#38091. Closes rust-lang#39687. Closes rust-lang#42148. Closes rust-lang#42956.

src/test/compile-fail/issue-39687.rs

@@ -0,0 +1,16 @@
+// Copyright 2018 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.
+
+#![feature(fn_traits)]
+
+fn main() {
+    <fn() as Fn()>::call;
+    //~^ ERROR associated type bindings are not allowed here [E0229]
+}

src/test/run-pass/issue-36792.rs

@@ -0,0 +1,17 @@
+// Copyright 2018 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.
+
+#![feature(conservative_impl_trait)]
+fn foo() -> impl Copy {
+    foo
+}
+fn main() {
+    foo();
+}

src/test/run-pass/issue-38091.rs

@@ -0,0 +1,29 @@
+// Copyright 2018 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.
+
+#![feature(specialization)]
+
+trait Iterate<'a> {
+    type Ty: Valid;
+    fn iterate(self);
+}
+impl<'a, T> Iterate<'a> for T where T: Check {
+    default type Ty = ();
+    default fn iterate(self) {}
+}
+
+trait Check {}
+impl<'a, T> Check for T where <T as Iterate<'a>>::Ty: Valid {}
+
+trait Valid {}
+
+fn main() {
+    Iterate::iterate(0);
+}

src/test/run-pass/issue-42148.rs

@@ -0,0 +1,15 @@
+// Copyright 2018 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.
+
+struct Zst;
+
+fn main() {
+    unsafe { ::std::ptr::write_volatile(1 as *mut Zst, Zst) }
+}

src/test/run-pass/issue-42956.rs

@@ -0,0 +1,33 @@
+// Copyright 2018 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.
+
+#![feature(associated_consts)]
+
+impl A for i32 {
+    type Foo = u32;
+}
+impl B for u32 {
+    const BAR: i32 = 0;
+}
+
+trait A {
+    type Foo: B;
+}
+
+trait B {
+    const BAR: i32;
+}
+
+fn generic<T: A>() {
+    // This panics if the universal function call syntax is used as well
+    println!("{}", T::Foo::BAR);
+}
+
+fn main() {}