fix: add missing CI script

Author: sebcrozet

.github/workflows/ci.yaml

@@ -53,7 +53,7 @@ jobs:
         id: setup
         run: |
           echo "version=$SLANG_TAG" >> $GITHUB_OUTPUT  # Output for cache key
-          SLANG_DIR=$(./download_slang.sh --version $SLANG_TAG | grep '^SLANG_DIR=' | cut -d'=' -f2-)
+          SLANG_DIR=$(./.github/workflows/download_slang.sh --version $SLANG_TAG | grep '^SLANG_DIR=' | cut -d'=' -f2-)
           echo "slang-dir=$SLANG_DIR" >> $GITHUB_OUTPUT  # Output for dependents
           echo "slang-cache-key=slang-v$SLANG_TAG-${{ runner.os }}-${{ runner.arch }}" >> $GITHUB_OUTPUT
           echo "SLANG_DIR=$SLANG_DIR" >> $GITHUB_ENV  # For this job if needed

.github/workflows/download_slang.sh

@@ -0,0 +1,109 @@
+#!/bin/bash
+
+# Default values
+OS=""
+OUTPUT_DIR="$HOME/.cache/slang"
+SLANG_VERSION=""
+SLANG_TAG=""
+ASSET_SUFFIX=""
+SLANG_URL_BASE="https://github.com/shader-slang/slang/releases/download"
+
+# Help message
+usage() {
+    echo "Usage: $0 [--os <linux|macos|macos-arm64|windows>] [--output-dir <path>] [--version <version>]"
+    echo "  --os: Target OS (default: auto-detect from current platform)"
+    echo "  --output-dir: Directory to extract Slang (default: ~/.cache/slang)"
+    echo "  --version: Slang version (e.g., 2025.18.2, default: latest)"
+    echo "Example: $0 --os linux --output-dir /tmp/slang"
+}
+
+# Parse arguments
+while [[ "$#" -gt 0 ]]; do
+    case $1 in
+        --os) OS="$2"; shift ;;
+        --output-dir) export OUTPUT_DIR="$2"; shift ;;
+        --version) export SLANG_VERSION="$2"; shift ;;
+        *) usage ; exit 1 ;;
+    esac
+    shift
+done
+
+# Detect OS if not specified
+if [[ -z "$OS" ]]; then
+    case "$(uname -s)" in
+        Linux*) OS="linux" ;;
+        Darwin*)
+            if [[ "$(uname -m)" == "arm64" ]]; then
+                OS="macos-aarch64"
+            else
+                OS="macos"
+            fi
+            ;;
+        CYGWIN*|MINGW*|MSYS*) OS="windows" ;;
+        *) echo "Error: Unable to detect OS. Specify --os (linux, macos, macos-arm64, windows)"; exit 1 ;;
+    esac
+fi
+
+# Determine asset suffix based on OS
+case "$OS" in
+    linux) ASSET_SUFFIX="linux-x86_64.zip" ;;
+    macos) ASSET_SUFFIX="macos-x86_64.zip" ;;
+    macos-aarch64) ASSET_SUFFIX="macos-aarch64.zip" ;;
+    windows) ASSET_SUFFIX="windows-x86_64.zip" ;;
+    *) echo "Error: Unsupported OS: $OS"; exit 1 ;;
+esac
+
+# Get Slang version if not specified
+if [[ -z "$SLANG_VERSION" ]]; then
+    export SLANG_TAG=$(curl -s https://api.github.com/repos/shader-slang/slang/releases/latest | grep '"tag_name"' | sed -E 's/.*"([^"]+)".*/\1/')
+    export SLANG_VERSION=$(echo "$SLANG_TAG" | sed 's/v//')  # e.g., v2025.18.2 -> 2025.18.2
+else
+    export SLANG_TAG="v$SLANG_VERSION"
+fi
+
+if [[ -z "$SLANG_VERSION" ]]; then
+    echo "Error: Could not determine Slang version"
+    exit 1
+fi
+
+# Set up paths
+SLANG_DIR="$OUTPUT_DIR/slang-v$SLANG_VERSION-$OS"
+ZIP_URL="$SLANG_URL_BASE/$SLANG_TAG/slang-$SLANG_VERSION-$ASSET_SUFFIX"
+TEMP_ZIP="/tmp/slang-$SLANG_VERSION.zip"
+
+# Check if Slang is already extracted
+if [[ -d "$SLANG_DIR" ]] && [[ -f "$SLANG_DIR/bin/slangc" || -f "$SLANG_DIR/bin/slangc.exe" ]]; then
+    echo "Using existing Slang at $SLANG_DIR"
+    echo "SLANG_DIR=$SLANG_DIR"
+    exit 0
+fi
+
+# Download Slang release
+echo "Downloading Slang v$SLANG_VERSION for $OS from $ZIP_URL..."
+mkdir -p "$OUTPUT_DIR"
+curl -L -o "$TEMP_ZIP" "$ZIP_URL" || { echo "Error: Download failed for $ZIP_URL"; exit 1; }
+
+# Extract based on OS
+echo "Extracting to $SLANG_DIR..."
+if [[ "$OS" == "windows" ]]; then
+    # Windows: Assume 7z is available (or adjust for PowerShell/Expand-Archive)
+    7z x "$TEMP_ZIP" -o"$SLANG_DIR" -y > /dev/null || { echo "Error: Extraction failed"; rm -f "$TEMP_ZIP"; exit 1; }
+else
+    # Linux/macOS: Use unzip
+    unzip -q "$TEMP_ZIP" -d "$SLANG_DIR" || { echo "Error: Extraction failed"; rm -f "$TEMP_ZIP"; exit 1; }
+fi
+
+# Clean up
+rm -f "$TEMP_ZIP"
+
+# Verify extraction
+if [[ ! -f "$SLANG_DIR/bin/slangc" && ! -f "$SLANG_DIR/bin/slangc.exe" ]]; then
+    echo "Error: Extraction incomplete, slangc not found in $SLANG_DIR/bin"
+    exit 1
+fi
+
+echo "Slang v$SLANG_VERSION extracted to $SLANG_DIR"
+echo "SLANG_DIR=$SLANG_DIR"
+
+# For use in calling script
+export SLANG_DIR