From d204cfd739bfecb6252b54c5007a28559d0f9a73 Mon Sep 17 00:00:00 2001
From: Niko Matsakis <niko@alum.mit.edu>
Date: Tue, 14 May 2013 09:26:21 -0400
Subject: [PATCH] Issue #5967: Make rvalues mutable

---
 src/librustc/middle/borrowck/gather_loans/lifetime.rs | 10 +++++++++-
 src/librustc/middle/mem_categorization.rs             |  2 +-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/src/librustc/middle/borrowck/gather_loans/lifetime.rs b/src/librustc/middle/borrowck/gather_loans/lifetime.rs
index 330d60a59d3a..b0ddf2057d9d 100644
--- a/src/librustc/middle/borrowck/gather_loans/lifetime.rs
+++ b/src/librustc/middle/borrowck/gather_loans/lifetime.rs
@@ -93,7 +93,7 @@ impl GuaranteeLifetimeContext {
                 let omit_root = (
                     ptr_mutbl == m_imm &&
                     self.bccx.is_subregion_of(self.loan_region, base_scope) &&
-                    base.mutbl.is_immutable() &&
+                    self.is_rvalue_or_immutable(base) &&
                     !self.is_moved(base)
                 );
 
@@ -168,6 +168,14 @@ impl GuaranteeLifetimeContext {
         }
     }
 
+    fn is_rvalue_or_immutable(&self,
+                              cmt: mc::cmt) -> bool {
+        cmt.mutbl.is_immutable() || match cmt.guarantor().cat {
+            mc::cat_rvalue => true,
+            _ => false
+        }
+    }
+
     fn check_root(&self,
                   cmt_deref: mc::cmt,
                   cmt_base: mc::cmt,
diff --git a/src/librustc/middle/mem_categorization.rs b/src/librustc/middle/mem_categorization.rs
index 95ed7fe8efcd..91c0b8e61cc7 100644
--- a/src/librustc/middle/mem_categorization.rs
+++ b/src/librustc/middle/mem_categorization.rs
@@ -551,7 +551,7 @@ pub impl mem_categorization_ctxt {
             id:elt.id(),
             span:elt.span(),
             cat:cat_rvalue,
-            mutbl:McImmutable,
+            mutbl:McDeclared,
             ty:expr_ty
         }
     }