Address feedback

.github/workflows/ci.yml

@@ -87,17 +87,18 @@ jobs:
       - uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4.1.1
         with:
           submodules: true
-      - uses: dtolnay/rust-toolchain@stable
       # Ensures --all-features builds correctly, the current logic will mean it
       # uses stock zlib, not cmake nor cc
       - run: |
           cargo test --target $TARGET_TRIPLE --all-features
           cargo run --target $TARGET_TRIPLE --manifest-path systest/Cargo.toml --all-features
       # Ensures zlib-ng builds and runs, though zlib-ng _could_ change internally
-      # and not use all optimizations available to the CI runner
+      # and not use all optimizations available to the CI runner, we do this here
+      # just for x86_64-unknown-linux-gnu to validate a common target compiles
+      # on a more recent compiler than the incredibly ancient one currently used by cross
       - run: |
-          cargo test --target $TARGET_TRIPLE --no-default-features --features zlib-ng-no-cmake-experimental-community-maintained
-          cargo run --target $TARGET_TRIPLE --manifest-path systest/Cargo.toml --no-default-features --features zlib-ng-no-cmake-experimental-community-maintained
+          cargo test --target $TARGET_TRIPLE --no-default-features --features zlib-ng-no-cmake-experimental-community-maintained || echo "::warning::failed to build libz-ng with --features zlib-ng-no-cmake-experimental-community-maintained"
+          cargo run --target $TARGET_TRIPLE --manifest-path systest/Cargo.toml --no-default-features --features zlib-ng-no-cmake-experimental-community-maintained || echo "::warning::failed to run systest with --features zlib-ng-no-cmake-experimental-community-maintained"
 
   linux:
     runs-on: ubuntu-latest

zng/cc.rs

@@ -313,9 +313,12 @@ pub fn build_zlib_ng(target: &str, compat: bool) {
             // neon
             cfg.define("ARM_NEON", None);
 
-            // TODO: These intrinsics were only added in gcc 9.4, which is _relatively_
+            // NOTE: These intrinsics were only added in gcc 9.4, which is _relatively_
             // recent, and if the define is not set zlib-ng just provides its
             // own implements, so maybe in a couple of years this can be toggled on
+            // if building with cc is merged it makes sense to put compiler intrinsic/header
+            // probing in a separate crate that can then be used here to enable
+            // those intrinsics if the compiler supports them
             // * vld1q_u16_x4
             // * vld1q_u8_x4
             // * vst1q_u16_x4