fix: install LLVM via direct download (bypass xlings extraction bug)

xlings 0.4.30 on Windows downloads LLVM (148MB) successfully but
silently fails to extract it. Download from xlings-res/llvm mirror
directly and extract with tar into the mcpp sandbox xpkgs structure.

This bypasses the xlings bug while keeping the same package layout.
Once xlings fixes the extraction issue, this can revert to
`xlings install llvm`.

Author: Sunrisepeak

.github/workflows/ci-windows.yml

@@ -56,7 +56,6 @@ jobs:
           export PATH="$USERPROFILE/.xlings/subos/default/bin:$PATH"
           echo "$USERPROFILE/.xlings/subos/default/bin" >> "$GITHUB_PATH"
           xlings.exe --version
-          xlings.exe install llvm -y
           xlings.exe install mcpp -y
           echo "=== Searching for mcpp binary ==="
           find "$USERPROFILE/.xlings" -name "mcpp.exe" -o -name "mcpp" 2>/dev/null | head -10
@@ -76,16 +75,19 @@ jobs:
         run: |
           export MCPP_VENDORED_XLINGS="$XLINGS_BIN"
 
-          # Pre-seed LLVM into mcpp sandbox from system xlings install
-          MCPP_XPKGS="$USERPROFILE/.mcpp/registry/data/xpkgs"
-          LLVM_SRC=$(find "$USERPROFILE/.xlings" -path "*/xim-x-llvm/20.1.7/bin/clang++.exe" 2>/dev/null | head -1)
-          if [ -n "$LLVM_SRC" ]; then
-            LLVM_PKG_DIR=$(dirname "$(dirname "$(dirname "$LLVM_SRC")")")
-            mkdir -p "$MCPP_XPKGS"
-            [ -d "$MCPP_XPKGS/xim-x-llvm" ] || cp -r "$LLVM_PKG_DIR" "$MCPP_XPKGS/xim-x-llvm"
-            echo "Pre-seeded LLVM from $LLVM_PKG_DIR"
-          else
-            echo "WARNING: LLVM not found after xlings install"
+          # Install LLVM directly — xlings 0.4.30 has a bug on Windows where
+          # large package extraction silently fails. Download and extract manually.
+          LLVM_VER="20.1.7"
+          LLVM_DEST="$USERPROFILE/.mcpp/registry/data/xpkgs/xim-x-llvm/$LLVM_VER"
+          if [ ! -f "$LLVM_DEST/bin/clang++.exe" ]; then
+            LLVM_URL="https://github.com/xlings-res/llvm/releases/download/$LLVM_VER/llvm-$LLVM_VER-windows-x86_64.tar.xz"
+            echo "Downloading LLVM $LLVM_VER..."
+            WORK=$(mktemp -d)
+            curl -fsSL -o "$WORK/llvm.tar.xz" "$LLVM_URL"
+            mkdir -p "$LLVM_DEST"
+            tar -xf "$WORK/llvm.tar.xz" -C "$LLVM_DEST" --strip-components=1
+            rm -rf "$WORK"
+            echo "LLVM installed: $(ls "$LLVM_DEST/bin/clang++.exe" 2>/dev/null && echo OK || echo FAILED)"
           fi
 
           "$MCPP" build

.github/workflows/release.yml

@@ -462,7 +462,6 @@ jobs:
           export PATH="$USERPROFILE/.xlings/subos/default/bin:$PATH"
           echo "$USERPROFILE/.xlings/subos/default/bin" >> "$GITHUB_PATH"
           xlings.exe --version
-          xlings.exe install llvm -y || xlings.exe install llvm@20.1.7 -y
           xlings.exe install mcpp -y
           MCPP=$(find "$USERPROFILE/.xlings" -name "mcpp.exe" -path "*/bin/*" 2>/dev/null | head -1)
           if [ -z "$MCPP" ]; then
@@ -481,17 +480,16 @@ jobs:
         run: |
           export MCPP_VENDORED_XLINGS="$XLINGS_BIN"
 
-          # Pre-seed LLVM into mcpp sandbox from system xlings
-          MCPP_XPKGS="$USERPROFILE/.mcpp/registry/data/xpkgs"
-          for src in "$USERPROFILE/.xlings/data/xpkgs/xim-x-llvm" \
-                     "$USERPROFILE/.xlings/subos/default/data/xpkgs/xim-x-llvm"; do
-            if [ -d "$src" ]; then
-              mkdir -p "$MCPP_XPKGS"
-              cp -r "$src" "$MCPP_XPKGS/xim-x-llvm"
-              echo "Pre-seeded LLVM from $src"
-              break
-            fi
-          done
+          # Install LLVM directly (xlings 0.4.30 extraction bug on Windows)
+          LLVM_VER="20.1.7"
+          LLVM_DEST="$USERPROFILE/.mcpp/registry/data/xpkgs/xim-x-llvm/$LLVM_VER"
+          if [ ! -f "$LLVM_DEST/bin/clang++.exe" ]; then
+            curl -fsSL -o /tmp/llvm.tar.xz \
+              "https://github.com/xlings-res/llvm/releases/download/$LLVM_VER/llvm-$LLVM_VER-windows-x86_64.tar.xz"
+            mkdir -p "$LLVM_DEST"
+            tar -xf /tmp/llvm.tar.xz -C "$LLVM_DEST" --strip-components=1
+            rm -f /tmp/llvm.tar.xz
+          fi
 
           "$MCPP" build