Add tests for -Zepoch using tyvar_raw_pointer

Author: Manishearth

src/test/compile-fail/epoch-raw-pointer-method-2015.rs

@@ -0,0 +1,23 @@
+// Copyright 2012 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.
+
+// ignore-tidy-linelength
+// compile-flags: -Zepoch=2015 -Zunstable-options
+
+// tests that epochs work with the tyvar warning-turned-error
+
+#[deny(warnings)]
+fn main() {
+    let x = 0;
+    let y = &x as *const _;
+    let _ = y.is_null();
+    //~^ error: the type of this value must be known in this context [tyvar_behind_raw_pointer]
+    //~^^ warning: this was previously accepted
+}

src/test/compile-fail/epoch-raw-pointer-method-2018.rs

@@ -0,0 +1,22 @@
+// Copyright 2012 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.
+
+// ignore-tidy-linelength
+// compile-flags: -Zepoch=2018 -Zunstable-options
+
+// tests that epochs work with the tyvar warning-turned-error
+
+#[deny(warnings)]
+fn main() {
+    let x = 0;
+    let y = &x as *const _;
+    let _ = y.is_null();
+    //~^ error: the type of this value must be known to call a method on a raw pointer on it [E0908]
+}