keccak: disable aarch64_sha3 backend on targets with softfloat ABI

.github/workflows/keccak.yml

@@ -32,6 +32,7 @@ jobs:
           - ${{needs.set-msrv.outputs.msrv}}
           - stable
         target:
+          - aarch64-unknown-none-softfloat
           - thumbv7em-none-eabi
           - wasm32-unknown-unknown
     steps:

keccak/CHANGELOG.md

@@ -5,8 +5,13 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## 0.2.0 (2026-03-16)
+## 0.2.1 (UNRELEASED)
+### Fixed
+- Warning on softfloat AArch64 targets by not enabling `aarch64_sha3` backend on them ([#126])
 
+[#126]: https://github.com/RustCrypto/sponges/pull/126
+
+## 0.2.0 (2026-03-16)
 ### Added
 - `keccak_backend` configuration parameter with `aarch64_sha3`, `simd128`,
   `simd256`, `simd512`, and `soft` values ([#105], [#106], [#113])

keccak/src/backends.rs

@@ -4,7 +4,7 @@ use crate::types::*;
 #[cfg(feature = "parallel")]
 use hybrid_array::ArraySize;
 
-#[cfg(target_arch = "aarch64")]
+#[cfg(all(target_arch = "aarch64", not(target_abi = "softfloat")))]
 pub(crate) mod aarch64_sha3;
 #[cfg(any(
     keccak_backend = "simd128",

keccak/src/lib.rs

@@ -28,15 +28,17 @@ pub use types::*;
 /// Struct which handles switching between available backends.
 #[derive(Debug, Copy, Clone)]
 pub struct Keccak {
-    #[cfg(target_arch = "aarch64")]
+    // TODO: remove `not(target_abi = "softfloat")` after the compiler is improved, see:
+    // https://github.com/rust-lang/rust/issues/160301
+    #[cfg(all(target_arch = "aarch64", not(target_abi = "softfloat")))]
     armv8_sha3: armv8_sha3_intrinsics::InitToken,
 }
 
 impl Default for Keccak {
     #[inline]
     fn default() -> Self {
         Self {
-            #[cfg(target_arch = "aarch64")]
+            #[cfg(all(target_arch = "aarch64", not(target_abi = "softfloat")))]
             armv8_sha3: armv8_sha3_intrinsics::init(),
         }
     }
@@ -65,6 +67,8 @@ impl Keccak {
             } else if #[cfg(keccak_backend = "aarch64_sha3")] {
                 #[cfg(not(target_arch = "aarch64"))]
                 compile_error!("aarch64_sha3 backend can be used only on AArch64 targets!");
+                #[cfg(target_abi = "softfloat")]
+                compile_error!("aarch64_sha3 backend can not be used with softfloat ABI!");
                 #[cfg(not(target_feature = "sha3"))]
                 compile_error!("aarch64_sha3 backend requires sha3 target feature to be enabled!");
 
@@ -74,7 +78,7 @@ impl Keccak {
             }
         );
 
-        #[cfg(target_arch = "aarch64")]
+        #[cfg(all(target_arch = "aarch64", not(target_abi = "softfloat")))]
         if self.armv8_sha3.get() {
             #[target_feature(enable = "sha3")]
             unsafe fn aarch64_sha3_inner(f: impl BackendClosure) {