Fix building arm64 wheel with cibuildwheel

Author: messense

CHANGELOG.md

@@ -5,6 +5,9 @@
 - Add support for `kebab-case` executable names. [#205](https://github.com/PyO3/setuptools-rust/pull/205)
 - Add support for custom cargo profiles. [#216](https://github.com/PyO3/setuptools-rust/pull/216)
 
+### Fixed
+- Fix building macOS arm64 wheel with cibuildwheel. [#217](https://github.com/PyO3/setuptools-rust/pull/217)
+
 ## 1.1.2 (2021-12-05)
 ### Changed
 - Removed dependency on `tomli` to simplify installation. [#200](https://github.com/PyO3/setuptools-rust/pull/200)

setuptools_rust/build.py

@@ -92,6 +92,12 @@ def run_for_extension(self, ext: RustExtension) -> None:
         universal2 = False
         if self.plat_name.startswith("macosx-") and arch_flags:
             universal2 = "x86_64" in arch_flags and "arm64" in arch_flags
+            if not universal2 and not self.target:
+                if "arm64" in arch_flags:
+                    self.target = "aarch64-apple-darwin"
+                elif "x86_64" in arch_flags:
+                    self.target = "x86_64-apple-darwin"
+
         if universal2:
             arm64_dylib_paths = self.build_extension(ext, "aarch64-apple-darwin")
             x86_64_dylib_paths = self.build_extension(ext, "x86_64-apple-darwin")