ci: add Arch Linux PHPT job

Tests against Arch's rolling-release PHP package to catch issues
with the latest system libraries and compiler versions.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: rudi-augment

.github/workflows/main.yml

@@ -39,6 +39,18 @@ jobs:
       - name: Test
         run: docker run --rm ext-ds
 
+  phpt-arch:
+    name: PHPT - Arch Linux
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Build
+        run: docker build -f Dockerfile.arch -t ext-ds .
+
+      - name: Test
+        run: docker run --rm ext-ds
+
   phpunit:
     name: PHPUnit - PHP ${{ matrix.php }}
     runs-on: ubuntu-latest

Dockerfile.arch

@@ -0,0 +1,22 @@
+FROM archlinux:latest
+
+RUN pacman -Syu --noconfirm \
+    php \
+    autoconf \
+    gcc \
+    make
+
+WORKDIR /ext-ds
+
+COPY . .
+
+RUN phpize --clean > /dev/null 2>&1 || true \
+    && phpize \
+    && ./configure \
+    && make -j$(nproc) \
+    && make install
+
+CMD php run-tests.php \
+    -d extension=ds.so \
+    -n -q --show-diff \
+    tests/