From 85defffea58139e3e5cc0811e499330fa24267ac Mon Sep 17 00:00:00 2001
From: James Miller <james@aatch.net>
Date: Thu, 19 Feb 2015 22:01:09 +0100
Subject: [PATCH] Improve borrowck error when a second move is due to a loop.

(Factoring of aatch CFG code, Part 5.)
---
 src/librustc_borrowck/borrowck/mod.rs | 27 ++++++++++++++++++++-------
 1 file changed, 20 insertions(+), 7 deletions(-)

diff --git a/src/librustc_borrowck/borrowck/mod.rs b/src/librustc_borrowck/borrowck/mod.rs
index dfd98881ace86..2479b6f2ab2bb 100644
--- a/src/librustc_borrowck/borrowck/mod.rs
+++ b/src/librustc_borrowck/borrowck/mod.rs
@@ -612,13 +612,26 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> {
                 };
                 let (suggestion, _) =
                     move_suggestion(param_env, expr_span, expr_ty, ("moved by default", ""));
-                self.tcx.sess.span_note(
-                    expr_span,
-                    &format!("`{}` moved here{} because it has type `{}`, which is {}",
-                            ol,
-                            moved_lp_msg,
-                            expr_ty.user_string(self.tcx),
-                            suggestion));
+                // If the two spans are the same, it's because the expression will be evaluated
+                // multiple times. Avoid printing the same span and adjust the wording so it makes
+                // more sense that it's from multiple evalutations.
+                if expr_span == use_span {
+                    self.tcx.sess.note(
+                        &format!("`{}` was previously moved here{} because it has type `{}`, \
+                                  which is {}",
+                                 ol,
+                                 moved_lp_msg,
+                                 expr_ty.user_string(self.tcx),
+                                 suggestion));
+                } else {
+                    self.tcx.sess.span_note(
+                        expr_span,
+                        &format!("`{}` moved here{} because it has type `{}`, which is {}",
+                                 ol,
+                                 moved_lp_msg,
+                                 expr_ty.user_string(self.tcx),
+                                 suggestion));
+                }
             }
 
             move_data::MovePat => {