1 files changed, 58 insertions, 0 deletions
diff --git a/src/test/ui/typeck/assign-non-lval-derefmut.stderr b/src/test/ui/typeck/assign-non-lval-derefmut.stderr
new file mode 100644
index 000000000..a6fcdfe21
--- /dev/null
+++ b/src/test/ui/typeck/assign-non-lval-derefmut.stderr
@@ -0,0 +1,58 @@
+error[E0070]: invalid left-hand side of assignment
+  --> $DIR/assign-non-lval-derefmut.rs:5:23
+   |
+LL |     x.lock().unwrap() = 2;
+   |     ----------------- ^
+   |     |
+   |     cannot assign to this expression
+   |
+help: consider dereferencing here to assign to the mutably borrowed value
+   |
+LL |     *x.lock().unwrap() = 2;
+   |     +
+
+error[E0368]: binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>`
+  --> $DIR/assign-non-lval-derefmut.rs:7:5
+   |
+LL |     x.lock().unwrap() += 1;
+   |     -----------------^^^^^
+   |     |
+   |     cannot use `+=` on type `MutexGuard<'_, usize>`
+   |
+help: `+=` can be used on `usize`, you can dereference `x.lock().unwrap()`
+   |
+LL |     *x.lock().unwrap() += 1;
+   |     +
+
+error[E0308]: mismatched types
+  --> $DIR/assign-non-lval-derefmut.rs:11:9
+   |
+LL |     let mut y = x.lock().unwrap();
+   |                 ----------------- expected due to this value
+LL |     y = 2;
+   |         ^ expected struct `MutexGuard`, found integer
+   |
+   = note: expected struct `MutexGuard<'_, usize>`
+                found type `{integer}`
+help: consider dereferencing here to assign to the mutably borrowed value
+   |
+LL |     *y = 2;
+   |     +
+
+error[E0368]: binary assignment operation `+=` cannot be applied to type `MutexGuard<'_, usize>`
+  --> $DIR/assign-non-lval-derefmut.rs:13:5
+   |
+LL |     y += 1;
+   |     -^^^^^
+   |     |
+   |     cannot use `+=` on type `MutexGuard<'_, usize>`
+   |
+help: `+=` can be used on `usize`, you can dereference `y`
+   |
+LL |     *y += 1;
+   |     +
+
+error: aborting due to 4 previous errors
+
+Some errors have detailed explanations: E0070, E0308, E0368.
+For more information about an error, try `rustc --explain E0070`.