Don't ICE when missing owned_box lang item

Closes #20549

src/librustc/middle/fast_reject.rs

@@ -71,8 +71,10 @@ pub fn simplify_type(tcx: &ty::ctxt,
         }
         ty::TyBox(_) => {
             // treat like we would treat `Box`
-            let def_id = tcx.lang_items.owned_box().unwrap();
-            Some(StructSimplifiedType(def_id))
+            match tcx.lang_items.require_owned_box() {
+                Ok(def_id) => Some(StructSimplifiedType(def_id)),
+                Err(msg) => tcx.sess.fatal(&msg),
+            }
         }
         ty::TyClosure(def_id, _) => {
             Some(ClosureSimplifiedType(def_id))

src/librustc/middle/lang_items.rs

@@ -90,6 +90,10 @@ impl LanguageItems {
         }
     }
 
+    pub fn require_owned_box(&self) -> Result<ast::DefId, String> {
+        self.require(OwnedBoxLangItem)
+    }
+
     pub fn from_builtin_kind(&self, bound: ty::BuiltinBound)
                              -> Result<ast::DefId, String>
     {

src/librustc_typeck/coherence/orphan.rs

@@ -77,7 +77,10 @@ impl<'cx, 'tcx> OrphanChecker<'cx, 'tcx> {
                         self.check_def_id(item, data.principal_def_id());
                     }
                     ty::TyBox(..) => {
-                        self.check_def_id(item, self.tcx.lang_items.owned_box().unwrap());
+                        match self.tcx.lang_items.require_owned_box() {
+                            Ok(trait_id) => self.check_def_id(item, trait_id),
+                            Err(msg) => self.tcx.sess.span_fatal(item.span, &msg),
+                        }
                     }
                     ty::TyChar => {
                         self.check_primitive_impl(def_id,

src/test/compile-fail/no_owned_box_lang_item.rs

@@ -0,0 +1,26 @@
+// Copyright 2015 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.
+
+// Test that we don't ICE when we are missing the owned_box lang item.
+
+// error-pattern: requires `owned_box` lang_item
+
+#![no_std]
+#![feature(lang_items, no_std, box_syntax)]
+
+extern crate core;
+
+fn main() {
+    let x = box 1i32;
+}
+
+#[lang = "stack_exhausted"] extern fn stack_exhausted() {}
+#[lang = "eh_personality"] extern fn eh_personality() {}
+#[lang = "panic_fmt"] fn panic_fmt() -> ! { loop {} }