src/test/ui/btreemap/btreemap-index-mut.stderr

   1 error[E0594]: cannot assign to data in an index of `BTreeMap<u32, u32>`
   2   --> $DIR/btreemap-index-mut.rs:5:5
   3    |
   4 LL |     map[&0] = 1;
   5    |     ^^^^^^^^^^^ cannot assign
   6    |
   7    = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `BTreeMap<u32, u32>`
   8 help: to modify a `BTreeMap<u32, u32>`, use `.get_mut()`, `.insert()` or the entry API
   9    |
  10 LL |     map.insert(&0, 1);
  11    |        ~~~~~~~~  ~  +
  12 LL |     map.get_mut(&0).map(|val| { *val = 1; });
  13    |        ~~~~~~~~~  ~~~~~~~~~~~~~~~~~~    ++++
  14 LL |     let val = map.entry(&0).or_insert(1);
  15    |     +++++++++    ~~~~~~~  ~~~~~~~~~~~~ +
  16
  17 error: aborting due to previous error
  18
  19 For more information about this error, try `rustc --explain E0594`.