Use libobjc2_src in objc2_sys when the vendor_gnustep feature is enabled

Author: madsmtm

.github/workflows/ci.yml

@@ -77,18 +77,6 @@ jobs:
         command: check
         args: --verbose --no-default-features
 
-    - name: Install GNUStep libobjc2
-      if: contains(matrix.platform.os, 'ubuntu')
-      run: |
-        wget https://github.com/gnustep/libobjc2/archive/refs/tags/v1.9.tar.gz
-        tar -xzf v1.9.tar.gz
-        mkdir libobjc2-1.9/build
-        cd libobjc2-1.9/build
-        export CC="clang"
-        export CXX="clang++"
-        cmake ../
-        sudo make install
-
     - name: Install GNUStep make
       if: contains(matrix.platform.os, 'ubuntu')
       run: |
@@ -122,7 +110,7 @@ jobs:
       with:
         command: test
         # Temporary fix
-        args: --verbose --no-fail-fast --no-default-features --package objc2_sys --package objc2 --package objc2_encode --package objc2_foundation
+        args: --verbose --no-fail-fast --no-default-features --features objc2_sys/vendor_gnustep --package objc2_sys --package objc2 --package objc2_encode --package objc2_foundation
 
     - name: Test
       if: ${{ !contains(matrix.platform.os, 'ubuntu') }}

libobjc2_src/README.md

@@ -2,4 +2,8 @@
 
 Source of GNUStep's libobjc2 and logic to build it for Rust.
 
-Using `clang` with at least version `8.0.0` is recommended. You can specify your desired compiler using the `CC` and `CXX` environment variables.
+You probably want to use `objc2_sys`, but this is kept separate from that so
+that users don't download the entire GNUStep source when they don't need to.
+
+Using `clang` with at least version `8.0.0` is recommended. You can specify
+your desired compiler using the `CC` and `CXX` environment variables.

objc2_sys/Cargo.toml

@@ -27,3 +27,10 @@ readme = "README.md"
 # See https://doc.rust-lang.org/cargo/reference/build-scripts.html#overriding-build-scripts
 links = "objc"
 build = "build.rs"
+
+[features]
+# If enabled, GNUStep's libobjc2 will be compiled and linked from source
+vendor_gnustep = ["libobjc2_src"]
+
+[build-dependencies]
+libobjc2_src = { path = "../libobjc2_src", optional = true }

objc2_sys/build.rs

@@ -1,23 +1,28 @@
-use std::env;
+#[cfg(feature = "vendor_gnustep")]
+fn main() {
+    let artifacts = libobjc2_src::build();
+    artifacts.print_cargo_metadata();
+    println!("cargo:rustc-cfg=gnustep");
+}
 
+#[cfg(not(feature = "vendor_gnustep"))]
 fn main() {
     // Only rerun if this file changes; the script doesn't depend on our code
     println!("cargo:rerun-if-changed=build.rs");
-    // Link to libobjc
-    println!("cargo:rustc-link-lib=dylib=objc");
 
-    let target_vendor = env::var("CARGO_CFG_TARGET_VENDOR").unwrap();
+    let target_vendor = std::env::var("CARGO_CFG_TARGET_VENDOR").unwrap();
 
-    // Adds useful #[cfg(apple)] and #[cfg(gnustep)] directives
     if target_vendor == "apple" {
+        // Add #[cfg(apple)] directive
         println!("cargo:rustc-cfg=apple");
     } else {
         // TODO: Are there other possibilities than GNUStep? Airyx? Is it
         // possible to use Apple's open source objc4 on other platforms?
+
+        // Add #[cfg(gnustep)] directive
         println!("cargo:rustc-cfg=gnustep");
-        // TODO: Should we vendor GNUStep's libobjc2?
-        // Using Cargo.toml:
-        // [target.'cfg(not(target_vendor = "apple"))'.build-dependencies]
-        // cc = "1.0"
     }
+
+    // Link to libobjc
+    println!("cargo:rustc-link-lib=dylib=objc");
 }