fix build on mac for real now?

setup.py

@@ -6,6 +6,8 @@
 from glob import glob
 
 from setuptools import Extension, setup
+from setuptools._distutils._log import log
+from setuptools._distutils._modified import newer_group
 from setuptools.command.build_ext import build_ext
 
 CWD = os.path.dirname(os.path.abspath(__file__))
@@ -55,14 +57,64 @@
         sources=["klujax.cpp", *suitesparse_sources],
         include_dirs=include_dirs,
         library_dirs=site.getsitepackages(),
-        extra_compile_args=[],  # clang defaults to c++17 and setting -std=c++17 prevents combined build with suitesparse c source.
+        extra_compile_args=["-std=c++17"],
         extra_link_args=[],
         language="c++",
     )
 else:
     raise RuntimError(f"Platform {sys.platform} not supported.")
 
 
+# Custom BuildExt to enable combined build of C and C++ files on MacOs (clang)
+# However, this class also removes some warnings when used on linux (gcc) and
+# Windows (cl) so we use it everywhere.
+class BuildExt(build_ext):
+    def build_extension(self, ext):
+        sources = ext.sources
+        c_sources = sorted([s for s in sources if s.endswith("c")])
+        cpp_sources = sorted([s for s in sources if s not in c_sources])
+        ext_path = self.get_ext_fullpath(ext.name)
+        macros = ext.define_macros[:]
+        for undef in ext.undef_macros:
+            macros.append((undef,))
+        c_objects = self.compiler.compile(
+            c_sources,
+            output_dir=self.build_temp,
+            macros=macros,
+            include_dirs=ext.include_dirs,
+            debug=self.debug,
+            extra_postargs=[
+                f
+                for f in ext.extra_compile_args
+                if not f in ["-std=c++17", "/std:c++17"]  # THIS IS OUR HACK
+            ],
+            depends=ext.depends,
+        )
+        cpp_objects = self.compiler.compile(
+            cpp_sources,
+            output_dir=self.build_temp,
+            macros=macros,
+            include_dirs=ext.include_dirs,
+            debug=self.debug,
+            extra_postargs=ext.extra_compile_args,
+            depends=ext.depends,
+        )
+        objects = c_objects + cpp_objects
+        extra_args = ext.extra_link_args or []
+        self.compiler.link_shared_object(
+            objects,
+            ext_path,
+            libraries=self.get_libraries(ext),
+            library_dirs=ext.library_dirs,
+            runtime_library_dirs=ext.runtime_library_dirs,
+            extra_postargs=extra_args,
+            export_symbols=self.get_export_symbols(ext),
+            debug=self.debug,
+            build_temp=self.build_temp,
+            target_lang=ext.language,
+        )
+
+
 setup(
     name="klujax",
     version="0.2.10",
@@ -74,7 +126,7 @@
     url="https://github.com/flaport/klujax",
     py_modules=["klujax"],
     ext_modules=[extension],
-    cmdclass={"build_ext": build_ext},
+    cmdclass={"build_ext": BuildExt},
     install_requires=["jax>=0.4.35", "jaxlib>=0.4.35"],
     python_requires=">=3.8",
     classifiers=[