ci: run cargo check with musl libc

.github/workflows/ci.yml

@@ -38,6 +38,10 @@ jobs:
       - name: Check
         run: cargo check --workspace --all-targets --all-features
 
+      # Check with musl libc target which is used for `deltachat-rpc-server` releases.
+      - name: Check musl
+        run: scripts/zig-musl-check.sh
+
   cargo_deny:
     name: cargo deny
     runs-on: ubuntu-latest

scripts/zig-musl-check.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+#
+# Run `cargo check` with musl libc.
+# This requires `zig` to compile vendored openssl.
+
+set -x
+set -e
+
+unset RUSTFLAGS
+
+# Pin Rust version to avoid uncontrolled changes in the compiler and linker flags.
+export RUSTUP_TOOLCHAIN=1.70.0
+
+ZIG_VERSION=0.11.0-dev.2213+515e1c93e
+
+# Download Zig
+rm -fr "$ZIG_VERSION" "zig-linux-x86_64-$ZIG_VERSION.tar.xz"
+wget "https://ziglang.org/builds/zig-linux-x86_64-$ZIG_VERSION.tar.xz"
+tar xf "zig-linux-x86_64-$ZIG_VERSION.tar.xz"
+export PATH="$PWD/zig-linux-x86_64-$ZIG_VERSION:$PATH"
+
+rustup target add x86_64-unknown-linux-musl
+CC="$PWD/scripts/zig-cc" \
+TARGET_CC="$PWD/scripts/zig-cc" \
+CARGO_TARGET_X86_64_UNKNOWN_LINUX_MUSL_LINKER="$PWD/scripts/zig-cc" \
+LD="$PWD/scripts/zig-cc" \
+ZIG_TARGET="x86_64-linux-musl" \
+cargo check --release --target x86_64-unknown-linux-musl -p deltachat_ffi --features jsonrpc