From 6fe370c7ceef08dbbaed6a502b0dde0ee0614db9 Mon Sep 17 00:00:00 2001
From: Matthew Jasper <mjjasper1@gmail.com>
Date: Wed, 30 Jan 2019 19:49:31 +0000
Subject: [PATCH] Pass correct arguments to places_conflict

The borrow place *must* be a place that we track borrows for, otherwise
we will likely ICE.
---
 src/librustc_mir/dataflow/impls/borrows.rs |  2 +-
 src/test/ui/nll/issue-57989.rs             | 12 +++++++++++
 src/test/ui/nll/issue-57989.stderr         | 24 ++++++++++++++++++++++
 3 files changed, 37 insertions(+), 1 deletion(-)
 create mode 100644 src/test/ui/nll/issue-57989.rs
 create mode 100644 src/test/ui/nll/issue-57989.stderr

diff --git a/src/librustc_mir/dataflow/impls/borrows.rs b/src/librustc_mir/dataflow/impls/borrows.rs
index 0ceff4aa04898..72218e29cfd20 100644
--- a/src/librustc_mir/dataflow/impls/borrows.rs
+++ b/src/librustc_mir/dataflow/impls/borrows.rs
@@ -215,8 +215,8 @@ impl<'a, 'gcx, 'tcx> Borrows<'a, 'gcx, 'tcx> {
             if places_conflict::places_conflict(
                 self.tcx,
                 self.mir,
-                place,
                 &borrow_data.borrowed_place,
+                place,
                 places_conflict::PlaceConflictBias::NoOverlap,
             ) {
                 debug!(
diff --git a/src/test/ui/nll/issue-57989.rs b/src/test/ui/nll/issue-57989.rs
new file mode 100644
index 0000000000000..4f21cca97cc09
--- /dev/null
+++ b/src/test/ui/nll/issue-57989.rs
@@ -0,0 +1,12 @@
+// Test for ICE from issue 57989
+
+#![feature(nll)]
+
+fn f(x: &i32) {
+    let g = &x;
+    *x = 0;     //~ ERROR cannot assign to `*x` which is behind a `&` reference
+                //~| ERROR cannot assign to `*x` because it is borrowed
+    g;
+}
+
+fn main() {}
diff --git a/src/test/ui/nll/issue-57989.stderr b/src/test/ui/nll/issue-57989.stderr
new file mode 100644
index 0000000000000..4561c99096f14
--- /dev/null
+++ b/src/test/ui/nll/issue-57989.stderr
@@ -0,0 +1,24 @@
+error[E0594]: cannot assign to `*x` which is behind a `&` reference
+  --> $DIR/issue-57989.rs:7:5
+   |
+LL | fn f(x: &i32) {
+   |         ---- help: consider changing this to be a mutable reference: `&mut i32`
+LL |     let g = &x;
+LL |     *x = 0;     //~ ERROR cannot assign to `*x` which is behind a `&` reference
+   |     ^^^^^^ `x` is a `&` reference, so the data it refers to cannot be written
+
+error[E0506]: cannot assign to `*x` because it is borrowed
+  --> $DIR/issue-57989.rs:7:5
+   |
+LL |     let g = &x;
+   |             -- borrow of `*x` occurs here
+LL |     *x = 0;     //~ ERROR cannot assign to `*x` which is behind a `&` reference
+   |     ^^^^^^ assignment to borrowed `*x` occurs here
+LL |                 //~| ERROR cannot assign to `*x` because it is borrowed
+LL |     g;
+   |     - borrow later used here
+
+error: aborting due to 2 previous errors
+
+Some errors occurred: E0506, E0594.
+For more information about an error, try `rustc --explain E0506`.