From e84581192d2629be07d622736ecbe6ce95f3ece0 Mon Sep 17 00:00:00 2001
From: Basile Desloges <basile.desloges@gmail.com>
Date: Thu, 21 Sep 2017 16:31:34 +0200
Subject: [PATCH] mir-borrowck: Add span labels to
 `report_use_while_mutably_borrowed()`

---
 src/librustc_mir/borrow_check.rs | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/librustc_mir/borrow_check.rs b/src/librustc_mir/borrow_check.rs
index 6ec01faf0002..f718038bb071 100644
--- a/src/librustc_mir/borrow_check.rs
+++ b/src/librustc_mir/borrow_check.rs
@@ -916,10 +916,15 @@ impl<'c, 'b, 'a: 'b+'c, 'gcx, 'tcx: 'a> MirBorrowckCtxt<'c, 'b, 'a, 'gcx, 'tcx>
                                          _context: Context,
                                          (lvalue, span): (&Lvalue, Span),
                                          borrow : &BorrowData) {
+        let described_lvalue = self.describe_lvalue(lvalue);
+        let borrow_span = self.retrieve_borrow_span(borrow);
+
         let mut err = self.tcx.cannot_use_when_mutably_borrowed(
-            span, &self.describe_lvalue(lvalue), Origin::Mir);
-        // FIXME 1: add span_label for "borrow of `()` occurs here"
-        // FIXME 2: add span_label for "use of `{}` occurs here"
+            span, &described_lvalue, Origin::Mir);
+
+        err.span_label(borrow_span, format!("borrow of `{}` occurs here", described_lvalue));
+        err.span_label(span, format!("use of borrowed `{}`", described_lvalue));
+
         err.emit();
     }