// overloaded lvalue ops, and will be fixed by them in order to get
// the correct region.
let mut source = self.node_ty(expr.id);
- if let Some(adjustments) = self.tables.borrow_mut().adjustments.get_mut(&expr.id) {
+ // Do not mutate adjustments in place, but rather take them,
+ // and replace them after mutating them, to avoid having the
+ // tables borrowed during (`deref_mut`) method resolution.
+ let previous_adjustments = self.tables.borrow_mut().adjustments.remove(&expr.id);
+ if let Some(mut adjustments) = previous_adjustments {
let pref = LvaluePreference::PreferMutLvalue;
- for adjustment in adjustments {
+ for adjustment in &mut adjustments {
if let Adjust::Deref(Some(ref mut deref)) = adjustment.kind {
if let Some(ok) = self.try_overloaded_deref(expr.span, source, pref) {
let method = self.register_infer_ok_obligations(ok);
}
source = adjustment.target;
}
+ self.tables.borrow_mut().adjustments.insert(expr.id, adjustments);
}
match expr.node {
--- /dev/null
+// Copyright 2017 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+use std::ops::{Deref, DerefMut};
+
+struct CheckedDeref<T, F> {
+ value: T,
+ check: F
+}
+
+impl<F: Fn(&T) -> bool, T> Deref for CheckedDeref<T, F> {
+ type Target = T;
+ fn deref(&self) -> &T {
+ assert!((self.check)(&self.value));
+ &self.value
+ }
+}
+
+impl<F: Fn(&T) -> bool, T> DerefMut for CheckedDeref<T, F> {
+ fn deref_mut(&mut self) -> &mut T {
+ assert!((self.check)(&self.value));
+ &mut self.value
+ }
+}
+
+
+fn main() {
+ let mut v = CheckedDeref {
+ value: vec![0],
+ check: |v: &Vec<_>| !v.is_empty()
+ };
+ v.push(1);
+ assert_eq!(*v, vec![0, 1]);
+}