Add docs and tests for assumptions about `rs_char` ABI compatibility.
PiperOrigin-RevId: 513662606
diff --git a/support/rs_std/rs_char.h b/support/rs_std/rs_char.h
index 6b22fc5..8bec775 100644
--- a/support/rs_std/rs_char.h
+++ b/support/rs_std/rs_char.h
@@ -13,6 +13,8 @@
namespace rs_std {
// `rs_std::rs_char` is a C++ representation of the `char` type from Rust.
+// `rust_builtin_type_abi_assumptions.md` documents the ABI compatiblity of
+// these types.
class rs_char final {
public:
// Creates a default `rs_char` - one that represents ASCII NUL character.
