[rust] Remove debug code (#6475)

* Remove debug code

This was added for testing in the recent genericize PR for flexbuffer Reader.

* Added alloc tests -> MapReader::{is_empty, index_key, len}

* Added , accessible through Deref to deprecation warning

rust/flexbuffers/src/reader/map.rs

@@ -71,8 +71,6 @@ impl<B: Buffer> std::fmt::Debug for MapReader<B> {
 impl<B: Buffer> MapReader<B> {
     /// Returns the number of key/value pairs are in the map.
     pub fn len(&self) -> usize {
-        let thing = self.clone();
-        println!("{:?}", &thing);
         self.length
     }
 

rust/flexbuffers/src/reader/mod.rs

@@ -306,7 +306,7 @@ impl<B: Buffer> Reader<B> {
     #[cfg(target_endian = "little")]
     #[deprecated(
         since = "0.3.0",
-        note = "This function is unsafe - if this functionality is needed it can be added separately via the `buffer` function."
+        note = "This function is unsafe - if this functionality is needed use `Reader::buffer::align_to`"
     )]
     pub fn get_slice<T: ReadLE>(&self) -> Result<&[T], Error> {
         if self.flexbuffer_type().typed_vector_type() != T::VECTOR_TYPE.typed_vector_type() {

tests/rust_usage_test/bin/flexbuffers_alloc_check.rs

@@ -70,6 +70,10 @@ fn make_monster(mut monster: MapBuilder) {
 fn validate_monster(flexbuffer: &[u8]) {
     let r = Reader::get_root(flexbuffer).unwrap().as_map();
 
+    assert!(!r.is_empty());
+    assert!(r.index_key("not_a_field").is_none());
+
+    assert_eq!(r.len(), 7);
     assert_eq!(r.idx("type").as_str(), "great orc");
     assert_eq!(r.idx("age").as_u8(), 100);
     assert_eq!(r.idx("name").as_str(), "Mr. Orc");