Merge pull request #23935 from veblush/pylibatomic

Make check_linker_need_libatomic more robust

setup.py

@@ -166,12 +166,22 @@ def check_linker_need_libatomic():
     """Test if linker on system needs libatomic."""
     code_test = (b'#include <atomic>\n' +
                  b'int main() { return std::atomic<int64_t>{}; }')
-    cc_test = subprocess.Popen(['cc', '-x', 'c++', '-std=c++11', '-'],
-                               stdin=PIPE,
-                               stdout=PIPE,
-                               stderr=PIPE)
-    cc_test.communicate(input=code_test)
-    return cc_test.returncode != 0
+    cpp_test = subprocess.Popen(['c++', '-x', 'c++', '-std=c++11', '-'],
+                                stdin=PIPE,
+                                stdout=PIPE,
+                                stderr=PIPE)
+    cpp_test.communicate(input=code_test)
+    if cpp_test.returncode == 0:
+        return False
+    # Double-check to see if -latomic actually can solve the problem.
+    # https://github.com/grpc/grpc/issues/22491
+    cpp_test = subprocess.Popen(
+        ['c++', '-x', 'c++', '-std=c++11', '-latomic', '-'],
+        stdin=PIPE,
+        stdout=PIPE,
+        stderr=PIPE)
+    cpp_test.communicate(input=code_test)
+    return cpp_test.returncode == 0
 
 
 # There are some situations (like on Windows) where CC, CFLAGS, and LDFLAGS are