Suggest .swap() instead of mem::swap() in more cases

3 files changed, 35 insertions, 0 deletions

diff --git a/tests/ui/suggestions/suggest-slice-swap.fixed b/tests/ui/suggestions/suggest-slice-swap.fixed
new file mode 100644
index 00000000000..05b7ec26379
--- /dev/null
+++ b/tests/ui/suggestions/suggest-slice-swap.fixed
@@ -0,0 +1,9 @@
+// run-rustfix
+#![allow(dead_code)]
+
+fn swap(arr: &mut [u32; 2]) {
+    arr.swap(1, 0);
+    //~^ ERROR cannot borrow `arr[_]` as mutable more than once at a time
+}
+
+fn main() {}
diff --git a/tests/ui/suggestions/suggest-slice-swap.rs b/tests/ui/suggestions/suggest-slice-swap.rs
new file mode 100644
index 00000000000..9f3659aac16
--- /dev/null
+++ b/tests/ui/suggestions/suggest-slice-swap.rs
@@ -0,0 +1,9 @@
+// run-rustfix
+#![allow(dead_code)]
+
+fn swap(arr: &mut [u32; 2]) {
+    std::mem::swap(&mut arr[0], &mut arr[1]);
+    //~^ ERROR cannot borrow `arr[_]` as mutable more than once at a time
+}
+
+fn main() {}
diff --git a/tests/ui/suggestions/suggest-slice-swap.stderr b/tests/ui/suggestions/suggest-slice-swap.stderr
new file mode 100644
index 00000000000..2840fc0a761
--- /dev/null
+++ b/tests/ui/suggestions/suggest-slice-swap.stderr
@@ -0,0 +1,17 @@
+error[E0499]: cannot borrow `arr[_]` as mutable more than once at a time
+  --> $DIR/suggest-slice-swap.rs:5:33
+   |
+LL |     std::mem::swap(&mut arr[0], &mut arr[1]);
+   |     -------------- -----------  ^^^^^^^^^^^ second mutable borrow occurs here
+   |     |              |
+   |     |              first mutable borrow occurs here
+   |     first borrow later used by call
+   |
+help: use `.swap()` to swap elements at the specified indices instead
+   |
+LL |     arr.swap(1, 0);
+   |     ~~~~~~~~~~~~~~
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0499`.