Deny warnings in CI and fix

.github/workflows/ci.yml

@@ -109,12 +109,12 @@ jobs:
         run: |
           case "${{ matrix.target_feature }}" in
             default)
-              ;;
+              echo "RUSTFLAGS=-Dwarnings" >> $GITHUB_ENV;;
             native)
-              echo "RUSTFLAGS=-Ctarget-cpu=native" >> $GITHUB_ENV
+              echo "RUSTFLAGS=-Dwarnings -Ctarget-cpu=native" >> $GITHUB_ENV
               ;;
             *)
-              echo "RUSTFLAGS=-Ctarget-feature=${{ matrix.target_feature }}" >> $GITHUB_ENV
+              echo "RUSTFLAGS=-Dwarnings -Ctarget-feature=${{ matrix.target_feature }}" >> $GITHUB_ENV
               ;;
           esac
 
@@ -251,4 +251,4 @@ jobs:
       - name: Check build
         run: cargo check --all-targets --no-default-features ${{ matrix.features }}
         env:
-            RUSTFLAGS: ${{ matrix.rustflags }}
+            RUSTFLAGS: -Dwarnings ${{ matrix.rustflags }}

crates/core_simd/src/intrinsics.rs

@@ -68,7 +68,9 @@ extern "platform-intrinsic" {
     // reductions
     pub(crate) fn simd_reduce_add_ordered<T, U>(x: T, y: U) -> U;
     pub(crate) fn simd_reduce_mul_ordered<T, U>(x: T, y: U) -> U;
+    #[allow(unused)]
     pub(crate) fn simd_reduce_all<T>(x: T) -> bool;
+    #[allow(unused)]
     pub(crate) fn simd_reduce_any<T>(x: T) -> bool;
     pub(crate) fn simd_reduce_max<T, U>(x: T) -> U;
     pub(crate) fn simd_reduce_min<T, U>(x: T) -> U;
@@ -77,6 +79,7 @@ extern "platform-intrinsic" {
     pub(crate) fn simd_reduce_xor<T, U>(x: T) -> U;
 
     // truncate integer vector to bitmask
+    #[allow(unused)]
     pub(crate) fn simd_bitmask<T, U>(x: T) -> U;
 
     // select

crates/core_simd/src/vendor.rs

@@ -1,4 +1,5 @@
 /// Provides implementations of `From<$a> for $b` and `From<$b> for $a` that transmutes the value.
+#[allow(unused)]
 macro_rules! from_transmute {
     { unsafe $a:ty => $b:ty } => {
         from_transmute!{ @impl $a => $b }