More robust way of checking whether the compiler is clang

setup.py

@@ -234,6 +234,18 @@ def compiler_has_flag(compiler, flagname):
     return True
 
 
+# Test whether the compiler is clang, allowing for the fact that it's name might be gcc...
+def compiler_is_clang(compiler):
+    # Test whether the compiler is clang by running the compiler with the --version flag and checking whether the output contains "clang"
+    try:
+        output = subprocess.check_output(
+            [compiler.compiler[0], "--version"], stderr=subprocess.STDOUT
+        )
+    except (OSError, subprocess.CalledProcessError):
+        return False
+    return b"clang" in output
+
+
 # Now need to subclass BuildExt to access the compiler used and check flags
 class BuildExt(build_ext):
     def build_extensions(self):
@@ -246,7 +258,8 @@ def build_extensions(self):
                 for flag in ext.extra_compile_args:
                     if compiler_has_flag(self.compiler, flag):
                         extra_compile_args.append(flag)
-                    elif "clang" in self.compiler.compiler[0] and flag == "-fopenmp":
+                    elif compiler_is_clang(self.compiler) and flag == "-fopenmp":
+                        print("Here")
                         # clang does not support -fopenmp, but does support -Xclang -fopenmp
                         extra_compile_args.append("-Xclang")
                         extra_compile_args.append("-fopenmp")