Add a comment showing how to update a hash generically.
This isn't obvious from the docs otherwise.
Change-Id: Id48a2cc18762a779e4834b6f6c1bea33020f6757
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/69807
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Auto-Submit: Adam Langley <agl@google.com>
diff --git a/rust/bssl-crypto/src/digest.rs b/rust/bssl-crypto/src/digest.rs
index 0ef0e8b..75c9867 100644
--- a/rust/bssl-crypto/src/digest.rs
+++ b/rust/bssl-crypto/src/digest.rs
@@ -28,6 +28,19 @@
//! let digest2: [u8; 32] = ctx.digest();
//!
//! assert_eq!(digest, digest2);
+//!
+//! // Hashing with dynamic dispatch.
+//! #[cfg(feature = "std")]
+//! {
+//! fn update_hash(ctx: &mut dyn std::io::Write) {
+//! ctx.write(b"hel");
+//! ctx.write(b"lo");
+//! }
+//!
+//! let mut ctx = digest::Sha256::new();
+//! update_hash(&mut ctx);
+//! assert_eq!(ctx.digest(), digest);
+//! }
//! ```
use crate::{sealed, FfiSlice, ForeignTypeRef};
