fix(ops): disallow memory slices as inputs to async ops (#16738)

In Rust, it is UB if a slice is mutated while borrowed except through
the slice itself, and it is also UB if a mutable slice is read while
borrowed. The op macro allows borrowing an `ArrayBuffer{,View}` as a
memory slice for the duration of an op, but this is not sound for async
ops, since the `ArrayBuffer` could be accessed from JS during the await
points. This PR therefore disallows such automatic borrowing only for
async ops.

Co-authored-by: Divy Srivastava <dj.srivastava23@gmail.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/ops/tests/compile_fail/mem_slices.rs b/ops/tests/compile_fail/mem_slices.rs
new file mode 100644
index 000000000..da74ac577
--- /dev/null
+++ b/ops/tests/compile_fail/mem_slices.rs
@@ -0,0 +1,24 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+
+use deno_ops::op;
+
+#[op]
+fn sync_test(slice: &mut [u32]) {
+  //
+}
+
+#[op]
+async fn async_test(slice: &[u8]) {
+  // Memory slices are not allowed in async ops.
+}
+
+#[op]
+fn async_test2(slice: &mut [u8]) -> impl Future<Output = ()> {
+  // Memory slices are not allowed in async ops, even when not implemented as an
+  // async function.
+  async {}
+}
+
+fn main() {
+  // pass
+}