ci: add musl build step

Author: ptondereau

.cargo/config.toml

@@ -6,3 +6,11 @@ linker = "rust-lld"
 
 [target.i686-pc-windows-msvc]
 linker = "rust-lld"
+
+[target.'cfg(target_env = "musl")']
+rustflags = [
+    "-C",
+    "target-feature=-crt-static",
+    "-C",
+    "link-arg=-Wl,-undefined,dynamic_lookup",
+]

.github/action/musl/Dockerfile

@@ -0,0 +1,54 @@
+FROM alpine:3.20
+
+ARG PHP_VERSION=8.4.1
+ARG PHP_BRANCH=PHP-${PHP_VERSION}
+ARG TS=ts
+
+RUN apk add --no-cache \
+    autoconf \
+    automake \
+    bison \
+    re2c \
+    gcc \
+    g++ \
+    make \
+    musl-dev \
+    linux-headers \
+    pkgconfig \
+    git \
+    curl \
+    libxml2-dev \
+    sqlite-dev \
+    openssl-dev \
+    curl-dev \
+    musl-dev \
+    clang17 \
+    clang17-libclang \
+    clang17-dev \
+    clang17-static
+
+WORKDIR /tmp/php-src
+RUN git clone --depth 1 -b ${PHP_BRANCH} https://github.com/php/php-src.git .
+
+RUN ./buildconf --force && \
+    CONFIGURE_OPTS="--enable-debug --enable-embed=shared --with-openssl --with-curl --with-sqlite3 --disable-cgi" && \
+    if [ "$TS" = "ts" ]; then CONFIGURE_OPTS="$CONFIGURE_OPTS --enable-zts"; fi && \
+    ./configure $CONFIGURE_OPTS --prefix=/usr/local && \
+    make -j$(nproc) && \
+    make install && \
+    rm -rf /tmp/php-src
+
+RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable
+ENV PATH="/root/.cargo/bin:${PATH}"
+
+RUN rustup target add x86_64-unknown-linux-musl
+
+ENV PHP=/usr/local/bin/php
+ENV PHP_CONFIG=/usr/local/bin/php-config
+
+WORKDIR /workspace
+
+COPY . .
+
+ENTRYPOINT ["cargo"]
+CMD ["build", "--release", "--no-default-features", "--features", "closure,anyhow,static,enum", "--workspace", "--target", "x86_64-unknown-linux-musl"]

.github/workflows/build.yml

@@ -168,7 +168,6 @@ jobs:
         # Macos fails on unstable rust. We skip the inline examples test for now.
         if: "!(contains(matrix.os, 'macos') && matrix.rust == 'nightly')"
         run: cargo test --release --workspace --features closure,anyhow,runtime --no-fail-fast
-
   test-embed:
     name: Test with embed
     runs-on: ubuntu-latest
@@ -226,3 +225,49 @@ jobs:
 
       - name: Test with embed feature
         run: cargo test --workspace --release --features closure,embed,anyhow --no-fail-fast
+
+  build-musl:
+    name: Musl
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        php: ["8.1", "8.2", "8.3", "8.4"]
+        phpts: [ts, nts]
+    env:
+      CARGO_TERM_COLOR: always
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v5
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
+      - name: Build Docker image with PHP ${{ matrix.php }}
+        uses: docker/build-push-action@v6
+        with:
+          context: .
+          file: .github/action/musl/Dockerfile
+          tags: ext-php-rs-musl:${{ matrix.php }}-${{ matrix.phpts }}
+          cache-from: type=gha,scope=musl-${{ matrix.php }}-${{ matrix.phpts }}
+          cache-to: type=gha,mode=max,scope=musl-${{ matrix.php }}-${{ matrix.phpts }}
+          build-args: |
+            PHP_VERSION=${{ matrix.php }}
+            TS=${{ matrix.phpts }}
+          load: true
+
+      - name: Build ext-php-rs with musl
+        run: |
+          docker run --rm \
+            -e EXT_PHP_RS_TEST="" \
+            -v ${{ github.workspace }}:/workspace \
+            -w /workspace \
+            ext-php-rs-musl:${{ matrix.php }}-${{ matrix.phpts }} \
+            build --release --no-default-features --features closure,anyhow,static,enum --workspace --target x86_64-unknown-linux-musl
+
+      - name: Test ext-php-rs with musl
+        run: |
+          docker run --rm \
+            -v ${{ github.workspace }}:/workspace \
+            -w /workspace \
+            ext-php-rs-musl:${{ matrix.php }}-${{ matrix.phpts }} \
+            test --release --workspace --no-default-features --features closure,anyhow,static,enum,embed --target x86_64-unknown-linux-musl --no-fail-fast

README.md

@@ -126,6 +126,22 @@ best resource at the moment. This can be viewed at [docs.rs].
     1.57 at the time of writing.
 - Clang 5.0 or later.
 
+### Alpine Linux (musl) Requirements
+
+Building for Alpine Linux (musl libc) is supported on stable Rust with the following
+requirements:
+
+- Install musl toolchain: `sudo apt-get install musl-tools musl-dev`
+- Add musl target: `rustup target add x86_64-unknown-linux-musl`
+- Build with dynamic linking flag:
+  ```bash
+  RUSTFLAGS="-C target-feature=-crt-static" \
+    cargo build --target x86_64-unknown-linux-musl
+  ```
+
+**Note**: Building for musl requires dynamic CRT linking (`-crt-static` flag) to produce
+the `cdylib` output required for PHP extensions.
+
 ### Windows Requirements
 
 - Extensions can only be compiled for PHP installations sourced from

tests/Cargo.toml

@@ -1,12 +1,15 @@
 [package]
 name = "tests"
 version = "0.0.0"
-edition = "2021"
+edition = "2024"
 publish = false
 license = "MIT OR Apache-2.0"
 
 [dependencies]
-ext-php-rs = { path = "../", default-features = false, features = ["closure", "runtime"] }
+ext-php-rs = { path = "../", default-features = false, features = [
+    "closure",
+    "runtime",
+] }
 
 [features]
 default = ["enum"]

tests/src/integration/mod.rs

@@ -36,11 +36,13 @@ mod test {
             {
                 command.arg("--features=enum");
             }
-            assert!(command
-                .output()
-                .expect("failed to build extension")
-                .status
-                .success());
+            assert!(
+                command
+                    .output()
+                    .expect("failed to build extension")
+                    .status
+                    .success()
+            );
         });
     }
 

tests/src/integration/variadic_args/mod.rs

@@ -79,10 +79,10 @@ pub fn test_variadic_first_last(items: &[&Zval]) -> Vec<Zval> {
     if let Some(first) = items.first() {
         result.push(first.shallow_clone());
     }
-    if let Some(last) = items.last() {
-        if items.len() > 1 {
-            result.push(last.shallow_clone());
-        }
+    if let Some(last) = items.last()
+        && items.len() > 1
+    {
+        result.push(last.shallow_clone());
     }
     result
 }