Allow taking address of bottom

Author: sanxiyn

src/librustc/middle/borrowck/gather_loans/mod.rs

@@ -230,12 +230,15 @@ fn gather_loans_in_expr(this: &mut GatherLoanCtxt,
 
         // make sure that the thing we are pointing out stays valid
         // for the lifetime `scope_r` of the resulting ptr:
-        let scope_r = ty_region(tcx, ex.span, ty::expr_ty(tcx, ex));
-        this.guarantee_valid(ex.id,
-                             ex.span,
-                             base_cmt,
-                             LoanMutability::from_ast_mutability(mutbl),
-                             scope_r);
+        let expr_ty = ty::expr_ty(tcx, ex);
+        if !ty::type_is_bot(expr_ty) {
+            let scope_r = ty_region(tcx, ex.span, expr_ty);
+            this.guarantee_valid(ex.id,
+                                 ex.span,
+                                 base_cmt,
+                                 LoanMutability::from_ast_mutability(mutbl),
+                                 scope_r);
+        }
         visit::walk_expr(this, ex, ());
       }
 

src/test/run-fail/addr-of-bot.rs

@@ -0,0 +1,15 @@
+// Copyright 2013 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.
+
+// error-pattern:explicit failure
+
+fn main() {
+    &fail!()
+}