Make objc2_exception work on GNUStep & WinObjc

Author: madsmtm

.github/workflows/ci.yml

@@ -10,6 +10,8 @@ env:
   RUST_BACKTRACE: 1
   # Faster compilation and error on warnings
   RUSTFLAGS: "-C debuginfo=0 -D warnings"
+  CC: clang
+  CXX: clang++
 
 jobs:
   fmt:
@@ -84,8 +86,6 @@ jobs:
         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
 
@@ -122,7 +122,15 @@ 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 --package objc2_sys --package objc2 --package objc2_encode --package objc2_exception --package objc2_foundation
+
+    - name: Test GNUStep with features
+      if: contains(matrix.platform.os, 'ubuntu')
+      uses: actions-rs/cargo@v1
+      with:
+        command: test
+        # Temporary fix
+        args: --verbose --no-fail-fast --no-default-features --features exception,verify_message --package objc2_sys --package objc2 --package objc2_encode --package objc2_exception --package objc2_foundation
 
     - name: Test
       if: ${{ !contains(matrix.platform.os, 'ubuntu') }}

objc2_exception/Cargo.toml

@@ -9,7 +9,7 @@ keywords = ["objective-c", "macos", "ios", "try", "catch"]
 categories = [
     "api-bindings",
     "development-tools::ffi",
-    "no-std",
+    # "no-std", # TODO
     "os::macos-apis",
 ]
 readme = "README.md"
@@ -19,5 +19,8 @@ license = "MIT"
 
 build = "build.rs"
 
+[dependencies]
+objc2_sys = { path = "../objc2_sys" }
+
 [build-dependencies]
 cc = "1"

objc2_exception/build.rs

@@ -1,6 +1,16 @@
+use std::env;
+
 fn main() {
-    cc::Build::new()
-        .file("extern/exception.m")
-        .flag("-fobjc-exceptions")
-        .compile("librustobjcexception.a");
+    println!("cargo:rerun-if-changed=extern/exception.m");
+
+    let mut builder = cc::Build::new();
+    builder.file("extern/exception.m");
+
+    // Assume the C compiler is clang; if it isn't, this is probably going to
+    // fail anyways.
+    for flag in env::var("DEP_OBJC_CLANG_ARGS").unwrap().split(' ') {
+        builder.flag(flag);
+    }
+
+    builder.compile("librust_objc_try_catch_exception.a");
 }

objc2_exception/extern/exception.m

@@ -1,10 +1,13 @@
-/// This is always available when building Objective-C.
+// Don't include any headers, cross compilation is difficult to set up
+// properly in such situations.
+
+/// We're linking to `libobjc` so this should be available.
 ///
 /// See <https://clang.llvm.org/docs/AutomaticReferenceCounting.html#arc-runtime-objc-retain>.
 id objc_retain(id value);
 
 // We return `unsigned char`, since it is guaranteed to be an `u8` on all platforms
-unsigned char RustObjCExceptionTryCatch(void (*f)(void *), void *context, id *error) {
+unsigned char rust_objc_try_catch_exception(void (*f)(void *), void *context, id *error) {
     @try {
         f(context);
         if (error) {

objc2_exception/src/lib.rs

@@ -22,22 +22,13 @@ use core::ffi::c_void;
 use core::mem;
 use core::ptr;
 
-#[link(name = "objc", kind = "dylib")]
-// TODO: "C-unwind"
-extern "C" {
-    /// See [`objc-exception.h`][objc-exception].
-    ///
-    /// [objc-exception]: https://opensource.apple.com/source/objc4/objc4-818.2/runtime/objc-exception.h.auto.html
-    // Header marks this with _Nonnull, but LLVM output shows otherwise
-    fn objc_exception_throw(exception: *mut c_void) -> !;
-    // fn objc_exception_rethrow();
-}
+use objc2_sys::{objc_exception_throw, objc_object};
 
 extern "C" {
-    fn RustObjCExceptionTryCatch(
+    fn rust_objc_try_catch_exception(
         f: extern "C" fn(*mut c_void),
         context: *mut c_void,
-        error: *mut *mut c_void,
+        error: *mut *mut objc_object,
     ) -> u8; // std::os::raw::c_uchar
 }
 
@@ -47,13 +38,7 @@ extern "C" {
 /// stabilized.
 ///
 /// [rfc-1861]: https://rust-lang.github.io/rfcs/1861-extern-types.html
-#[repr(C)]
-pub struct Exception {
-    /// See the [Nomicon] for details on representing opaque structs.
-    ///
-    /// [Nomicon]: https://doc.rust-lang.org/nomicon/ffi.html#representing-opaque-structs
-    _priv: [u8; 0],
-}
+pub type Exception = objc_object;
 
 /// Throws an Objective-C exception.
 ///
@@ -70,7 +55,7 @@ pub struct Exception {
 /// [RFC-2945]: https://rust-lang.github.io/rfcs/2945-c-unwind-abi.html
 #[inline]
 pub unsafe fn throw(exception: *mut Exception) -> ! {
-    objc_exception_throw(exception as *mut _)
+    objc_exception_throw(exception)
 }
 
 unsafe fn try_no_ret<F: FnOnce()>(closure: F) -> Result<(), *mut Exception> {
@@ -87,12 +72,12 @@ unsafe fn try_no_ret<F: FnOnce()>(closure: F) -> Result<(), *mut Exception> {
     let context = &mut closure as *mut _ as *mut c_void;
 
     let mut exception = ptr::null_mut();
-    let success = RustObjCExceptionTryCatch(f, context, &mut exception);
+    let success = rust_objc_try_catch_exception(f, context, &mut exception);
 
     if success == 0 {
         Ok(())
     } else {
-        Err(exception as *mut _)
+        Err(exception)
     }
 }
 

objc2_sys/build.rs

@@ -160,9 +160,10 @@ fn main() {
 
     // Add clang arguments
     println!(
-        "cargo:clang_args=-fobjc-arc -fobjc-arc-exceptions -fobjc-exceptions -fobjc-weak -fobjc-runtime={}",
-        // -fobjc-arc implies -fobjc-link-runtime, so people actually don't
-        // even need to specify `-lobjc` (though they probably still should).
+        "cargo:clang_args=-fobjc-link-runtime -fobjc-arc -fobjc-arc-exceptions -fobjc-exceptions -fobjc-runtime={}",
+        // `-fobjc-link-runtime` -> people don't need to specify `-lobjc`.
+
+        // -fobjc-weak ?
         clang_runtime
     ); // DEP_OBJC_CLANG_ARGS
 

objc2_sys/src/exception.rs

@@ -34,6 +34,9 @@ pub type objc_exception_handler =
 extern "C" {
     pub fn objc_begin_catch(exc_buf: *mut c_void) -> *mut objc_object;
     pub fn objc_end_catch();
+    /// See [`objc-exception.h`][objc-exception].
+    ///
+    /// [objc-exception]: https://opensource.apple.com/source/objc4/objc4-818.2/runtime/objc-exception.h.auto.html
     pub fn objc_exception_throw(exception: *mut objc_object) -> !;
     #[cfg(apple)]
     pub fn objc_exception_rethrow() -> !;