feat(ci): add Rust x86_64-apple-darwin target installation for macOS builds

.github/workflows/build-release.yml

@@ -475,6 +475,10 @@ jobs:
                       exit 1
                   fi
 
+            - name: Install Rust x86_64-apple-darwin target (cbor2 x64 slice)
+              if: matrix.label == 'macos'
+              run: bash scripts/ci/github-macos-rust-x64-target.sh
+
             - name: Install project deps into x64 Python (mac universal cx_Freeze)
               if: matrix.label == 'macos'
               env:

.github/workflows/build.yml

@@ -121,6 +121,10 @@ jobs:
                   set -euo pipefail
                   arch -x86_64 /usr/local/bin/brew install codec2
 
+            - name: Install Rust x86_64-apple-darwin target (cbor2 x64 slice)
+              if: matrix.label == 'macos'
+              run: bash scripts/ci/github-macos-rust-x64-target.sh
+
             - name: Install project deps into x64 Python (mac universal cx_Freeze)
               if: matrix.label == 'macos'
               env:

scripts/ci/github-macos-rust-x64-target.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+# Rust cross-target for x86_64 macOS wheels built on Apple Silicon CI runners.
+set -euo pipefail
+
+if [[ "$(uname -s)" != "Darwin" ]]; then
+    exit 0
+fi
+
+if ! command -v rustup >/dev/null 2>&1; then
+    echo "Installing rustup (minimal stable) for macOS x86_64 cross-builds." >&2
+    curl -sSfL https://sh.rustup.rs -o /tmp/rustup-init.sh
+    sh /tmp/rustup-init.sh -y --profile minimal --default-toolchain stable
+    rm -f /tmp/rustup-init.sh
+fi
+
+if [[ -d "${HOME}/.cargo/bin" ]]; then
+    if [[ -n "${GITHUB_PATH:-}" ]]; then
+        echo "${HOME}/.cargo/bin" >> "${GITHUB_PATH}"
+    else
+        export PATH="${HOME}/.cargo/bin:${PATH}"
+    fi
+fi
+if [[ -f "${HOME}/.cargo/env" ]]; then
+    # shellcheck disable=SC1091
+    source "${HOME}/.cargo/env"
+fi
+
+rustup target add x86_64-apple-darwin
+rustup show