From 64a2163958eadfd7ba34cff5716ca4264db55e54 Mon Sep 17 00:00:00 2001
From: Remix7531 <131352678+remix7531@users.noreply.github.com>
Date: Wed, 18 Feb 2026 21:35:36 +0100
Subject: [PATCH] digest: add blanket-impls feature to gate blanket Digest impl

Add a new `blanket-impls` feature flag (enabled by default) that gates
the blanket `impl<D: FixedOutput + Default + Update + HashMarker> Digest
for D` implementation. This allows downstream crates that provide their
own manual `Digest` implementations to disable the blanket impl and
avoid coherence conflicts.
---
 digest/Cargo.toml    | 3 ++-
 digest/src/digest.rs | 1 +
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/digest/Cargo.toml b/digest/Cargo.toml
index 305918d9e..1ebb09406 100644
--- a/digest/Cargo.toml
+++ b/digest/Cargo.toml
@@ -26,9 +26,10 @@ zeroize = { version = "1.7", optional = true, default-features = false }
 sha2 = "0.11.0-rc.5"
 
 [features]
-default = ["block-api"]
+default = ["block-api", "blanket-impls"]
 alloc = []
 block-api = ["dep:block-buffer"] # Enable block API traits
+blanket-impls = [] # Enable blanket implementations of Digest and other traits
 dev = ["blobby"]
 getrandom = ["common/getrandom", "rand_core"]
 mac = ["dep:ctutils"] # Enable MAC traits
diff --git a/digest/src/digest.rs b/digest/src/digest.rs
index 30cb3d8af..46d5ff873 100644
--- a/digest/src/digest.rs
+++ b/digest/src/digest.rs
@@ -56,6 +56,7 @@ pub trait Digest: OutputSizeUser {
     fn digest(data: impl AsRef<[u8]>) -> Output<Self>;
 }
 
+#[cfg(feature = "blanket-impls")]
 impl<D: FixedOutput + Default + Update + HashMarker> Digest for D {
     #[inline]
     fn new() -> Self {