Mark endian_scalar as unsafe. (#6588)

* Mark endian_scalar as unsafe.

Also
- removed the deprecated flexbuffer slice from example
- fixed some cargo warnings

* Assertions and read_scalar made unsafe

* Clippy lints

* Add to Safety

Co-authored-by: Casper Neo <cneo@google.com>

2 files changed, 8 insertions, 22 deletions

diff --git a/samples/monster_generated.rs b/samples/monster_generated.rs
index d2f17ee5..b3d82674 100644
--- a/samples/monster_generated.rs
+++ b/samples/monster_generated.rs
@@ -76,7 +76,9 @@ impl<'a> flatbuffers::Follow<'a> for Color {
   type Inner = Self;
   #[inline]
   fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
-    let b = flatbuffers::read_scalar_at::<i8>(buf, loc);
+    let b = unsafe {
+      flatbuffers::read_scalar_at::<i8>(buf, loc)
+    };
     Self(b)
   }
 }
@@ -85,7 +87,7 @@ impl flatbuffers::Push for Color {
     type Output = Color;
     #[inline]
     fn push(&self, dst: &mut [u8], _rest: &[u8]) {
-        flatbuffers::emplace_scalar::<i8>(dst, self.0);
+        unsafe { flatbuffers::emplace_scalar::<i8>(dst, self.0); }
     }
 }
 
@@ -161,7 +163,9 @@ impl<'a> flatbuffers::Follow<'a> for Equipment {
   type Inner = Self;
   #[inline]
   fn follow(buf: &'a [u8], loc: usize) -> Self::Inner {
-    let b = flatbuffers::read_scalar_at::<u8>(buf, loc);
+    let b = unsafe {
+      flatbuffers::read_scalar_at::<u8>(buf, loc)
+    };
     Self(b)
   }
 }
@@ -170,7 +174,7 @@ impl flatbuffers::Push for Equipment {
     type Output = Equipment;
     #[inline]
     fn push(&self, dst: &mut [u8], _rest: &[u8]) {
-        flatbuffers::emplace_scalar::<u8>(dst, self.0);
+        unsafe { flatbuffers::emplace_scalar::<u8>(dst, self.0); }
     }
 }
 
diff --git a/samples/sample_flexbuffers.rs b/samples/sample_flexbuffers.rs
index 677bcacb..237dbf0b 100644
--- a/samples/sample_flexbuffers.rs
+++ b/samples/sample_flexbuffers.rs
@@ -149,24 +149,6 @@ fn main() {
         .iter()
         .map(|r| r.as_u8())
         .eq(vec![5, 10, 25, 25, 25, 100].into_iter()));
-    // For very speed sensitive applications, you can directly read the slice if all of the
-    // following are true:
-    //
-    // *   The provided data buffer contains a valid flexbuffer.
-    // *   You correctly specify the flexbuffer type and width.
-    // *   The host machine is little endian.
-    // *   The provided data buffer itself is aligned in memory to 8 bytes.
-    //
-    // Vec<u8> has alignment 1 so special care is needed to get your buffer's alignment to 8.
-    #[cfg(target_endian = "little")]
-    {
-        if monster_coins.is_aligned() {
-            assert_eq!(
-                monster_coins.get_slice::<i8>().unwrap(),
-                &[5, 10, 25, 25, 25, 100]
-            );
-        }
-    }
 
     // Build the answer to life the universe and everything. Reusing a builder resets it. The
     // reused internals won't need to reallocate leading to a potential 2x speedup.