Swapped order of left/right visits to ensure consistency in read/write pass ordering when -O is passed.

Author: davidtwco

src/librustc_mir/borrow_check/mod.rs

@@ -347,20 +347,20 @@ impl<'cx, 'gcx, 'tcx> DataflowResultsConsumer<'cx, 'tcx> for MirBorrowckCtxt<'cx
 
         match stmt.kind {
             StatementKind::Assign(ref lhs, ref rhs) => {
+                self.consume_rvalue(
+                    ContextKind::AssignRhs.new(location),
+                    (rhs, span),
+                    location,
+                    flow_state,
+                );
+
                 self.mutate_place(
                     ContextKind::AssignLhs.new(location),
                     (lhs, span),
                     Shallow(None),
                     JustWrite,
                     flow_state,
                 );
-
-                self.consume_rvalue(
-                    ContextKind::AssignRhs.new(location),
-                    (rhs, span),
-                    location,
-                    flow_state,
-                );
             }
             StatementKind::SetDiscriminant {
                 ref place,

src/test/compile-fail/nll/reference-carried-through-struct-field.rs

@@ -19,7 +19,7 @@ fn foo() {
     let mut x = 22;
     let wrapper = Wrap { w: &mut x };
     x += 1; //[ast]~ ERROR cannot assign to `x` because it is borrowed [E0506]
-    //[mir]~^ ERROR cannot assign to `x` because it is borrowed [E0506]
+    //[mir]~^ ERROR cannot use `x` because it was mutably borrowed [E0503]
     *wrapper.w += 1;
 }
 

src/test/ui/issue-45697.rs

@@ -29,7 +29,7 @@ fn main() {
         let z = copy_borrowed_ptr(&mut y);
         *y.pointer += 1;
         //~^ ERROR cannot assign to `*y.pointer` because it is borrowed (Ast) [E0506]
-        //~| ERROR cannot assign to `*y.pointer` because it is borrowed (Mir) [E0506]
+        //~| ERROR cannot use `*y.pointer` because it was mutably borrowed (Mir) [E0503]
         *z.pointer += 1;
     }
 }

src/test/ui/issue-45697.stderr

@@ -6,13 +6,13 @@ error[E0506]: cannot assign to `*y.pointer` because it is borrowed (Ast)
 30 |         *y.pointer += 1;
    |         ^^^^^^^^^^^^^^^ assignment to borrowed `*y.pointer` occurs here
 
-error[E0506]: cannot assign to `*y.pointer` because it is borrowed (Mir)
+error[E0503]: cannot use `*y.pointer` because it was mutably borrowed (Mir)
   --> $DIR/issue-45697.rs:30:9
    |
 29 |         let z = copy_borrowed_ptr(&mut y);
-   |                                   ------ borrow of `*y.pointer` occurs here
+   |                                   ------ borrow of `y` occurs here
 30 |         *y.pointer += 1;
-   |         ^^^^^^^^^^^^^^^ assignment to borrowed `*y.pointer` occurs here
+   |         ^^^^^^^^^^^^^^^ use of borrowed `y`
 
 error: aborting due to 2 previous errors