We are currently solving the following issue within our repository. Here is the issue text:
--- BEGIN ISSUE ---
mmcv error
My environment is macOS Mojave 10.14.4, Anaconda 4.4.0,Python 3.6.1.
 I directly use "pip install mmcv and got:
"Running setup.py clean for mmcv
Failed to build mmcv
Installing collected packages: mmcv
Running setup.py install for mmcv ... error" and :
"In file included from ./mmcv/video/optflow_warp/flow_warp.cpp:1:
./mmcv/video/optflow_warp/flow_warp.hpp:3:10: fatal error: 'iostream' file not found
#include <iostream>"
Anybody help? Thank you very much.

--- END ISSUE ---

Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
--- BEGIN FILES ---
Path: `setup.py`
Content:
```
1 import sys
2 from io import open  # for Python 2 (identical to builtin in Python 3)
3 
4 from setuptools import Extension, find_packages, setup
5 
6 import numpy
7 from Cython.Distutils import build_ext
8 
9 install_requires = [
10     'numpy>=1.11.1', 'pyyaml', 'six', 'addict', 'requests', 'opencv-python',
11     'Cython'
12 ]
13 if sys.version_info < (3, 3):
14     install_requires.append('backports.shutil_get_terminal_size')
15 if sys.version_info < (3, 4):
16     install_requires.extend(['enum34', 'pathlib'])
17 
18 
19 def readme():
20     with open('README.rst', encoding='utf-8') as f:
21         content = f.read()
22     return content
23 
24 
25 def get_version():
26     version_file = 'mmcv/version.py'
27     with open(version_file, 'r', encoding='utf-8') as f:
28         exec(compile(f.read(), version_file, 'exec'))
29     return locals()['__version__']
30 
31 
32 EXT_MODULES = [
33     Extension(
34         name='mmcv._ext',
35         sources=[
36             './mmcv/video/optflow_warp/flow_warp.cpp',
37             './mmcv/video/optflow_warp/flow_warp_module.pyx'
38         ],
39         include_dirs=[numpy.get_include()],
40         language="c++",
41     ),
42 ]
43 
44 setup(
45     name='mmcv',
46     version=get_version(),
47     description='Open MMLab Computer Vision Foundation',
48     long_description=readme(),
49     keywords='computer vision',
50     packages=find_packages(),
51     classifiers=[
52         'Development Status :: 4 - Beta',
53         'License :: OSI Approved :: Apache Software License',
54         'Operating System :: OS Independent',
55         'Programming Language :: Python :: 2',
56         'Programming Language :: Python :: 2.7',
57         'Programming Language :: Python :: 3',
58         'Programming Language :: Python :: 3.4',
59         'Programming Language :: Python :: 3.5',
60         'Programming Language :: Python :: 3.6',
61         'Programming Language :: Python :: 3.7',
62         'Topic :: Utilities',
63     ],
64     url='https://github.com/open-mmlab/mmcv',
65     author='Kai Chen',
66     author_email='chenkaidev@gmail.com',
67     setup_requires=['pytest-runner'],
68     tests_require=['pytest'],
69     install_requires=install_requires,
70     ext_modules=EXT_MODULES,
71     cmdclass={'build_ext': build_ext},
72     zip_safe=False)
73
```
--- END FILES ---

Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.

Here is an example:

```diff
diff --git a/examples/server_async.py b/examples/server_async.py
--- a/examples/server_async.py
+++ b/examples/server_async.py
@@ -313,4 +313,4 @@
 
 
 if __name__ == "__main__":
-    asyncio.run(run_async_server("."), debug=True)
+    asyncio.run(run_async_server(), debug=True)
diff --git a/examples/server_sync.py b/examples/server_sync.py
--- a/examples/server_sync.py
+++ b/examples/server_sync.py
@@ -313,5 +313,5 @@
 
 
 if __name__ == "__main__":
-    server = run_sync_server(".")
+    server = run_sync_server()
     server.shutdown()

```

diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -1,6 +1,6 @@
+import platform
 import sys
 from io import open  # for Python 2 (identical to builtin in Python 3)
-
 from setuptools import Extension, find_packages, setup
 
 import numpy
@@ -29,6 +29,13 @@
     return locals()['__version__']
 
 
+if platform.system() == 'Darwin':
+    extra_compile_args = ['-stdlib=libc++']
+    extra_link_args = ['-stdlib=libc++']
+else:
+    extra_compile_args = []
+    extra_link_args = []
+
 EXT_MODULES = [
     Extension(
         name='mmcv._ext',
@@ -37,7 +44,9 @@
             './mmcv/video/optflow_warp/flow_warp_module.pyx'
         ],
         include_dirs=[numpy.get_include()],
-        language="c++",
+        language='c++',
+        extra_compile_args=extra_compile_args,
+        extra_link_args=extra_link_args,
     ),
 ]

{"golden_diff": "diff --git a/setup.py b/setup.py\n--- a/setup.py\n+++ b/setup.py\n@@ -1,6 +1,6 @@\n+import platform\n import sys\n from io import open  # for Python 2 (identical to builtin in Python 3)\n-\n from setuptools import Extension, find_packages, setup\n \n import numpy\n@@ -29,6 +29,13 @@\n     return locals()['__version__']\n \n \n+if platform.system() == 'Darwin':\n+    extra_compile_args = ['-stdlib=libc++']\n+    extra_link_args = ['-stdlib=libc++']\n+else:\n+    extra_compile_args = []\n+    extra_link_args = []\n+\n EXT_MODULES = [\n     Extension(\n         name='mmcv._ext',\n@@ -37,7 +44,9 @@\n             './mmcv/video/optflow_warp/flow_warp_module.pyx'\n         ],\n         include_dirs=[numpy.get_include()],\n-        language=\"c++\",\n+        language='c++',\n+        extra_compile_args=extra_compile_args,\n+        extra_link_args=extra_link_args,\n     ),\n ]\n", "issue": "mmcv error\nMy environment is macOS Mojave 10.14.4, Anaconda 4.4.0,Python 3.6.1.\r\n I directly use \"pip install mmcv and got:\r\n\"Running setup.py clean for mmcv\r\nFailed to build mmcv\r\nInstalling collected packages: mmcv\r\nRunning setup.py install for mmcv ... error\" and :\r\n\"In file included from ./mmcv/video/optflow_warp/flow_warp.cpp:1:\r\n./mmcv/video/optflow_warp/flow_warp.hpp:3:10: fatal error: 'iostream' file not found\r\n#include <iostream>\"\r\nAnybody help? Thank you very much.\n", "before_files": [{"content": "import sys\nfrom io import open  # for Python 2 (identical to builtin in Python 3)\n\nfrom setuptools import Extension, find_packages, setup\n\nimport numpy\nfrom Cython.Distutils import build_ext\n\ninstall_requires = [\n    'numpy>=1.11.1', 'pyyaml', 'six', 'addict', 'requests', 'opencv-python',\n    'Cython'\n]\nif sys.version_info < (3, 3):\n    install_requires.append('backports.shutil_get_terminal_size')\nif sys.version_info < (3, 4):\n    install_requires.extend(['enum34', 'pathlib'])\n\n\ndef readme():\n    with open('README.rst', encoding='utf-8') as f:\n        content = f.read()\n    return content\n\n\ndef get_version():\n    version_file = 'mmcv/version.py'\n    with open(version_file, 'r', encoding='utf-8') as f:\n        exec(compile(f.read(), version_file, 'exec'))\n    return locals()['__version__']\n\n\nEXT_MODULES = [\n    Extension(\n        name='mmcv._ext',\n        sources=[\n            './mmcv/video/optflow_warp/flow_warp.cpp',\n            './mmcv/video/optflow_warp/flow_warp_module.pyx'\n        ],\n        include_dirs=[numpy.get_include()],\n        language=\"c++\",\n    ),\n]\n\nsetup(\n    name='mmcv',\n    version=get_version(),\n    description='Open MMLab Computer Vision Foundation',\n    long_description=readme(),\n    keywords='computer vision',\n    packages=find_packages(),\n    classifiers=[\n        'Development Status :: 4 - Beta',\n        'License :: OSI Approved :: Apache Software License',\n        'Operating System :: OS Independent',\n        'Programming Language :: Python :: 2',\n        'Programming Language :: Python :: 2.7',\n        'Programming Language :: Python :: 3',\n        'Programming Language :: Python :: 3.4',\n        'Programming Language :: Python :: 3.5',\n        'Programming Language :: Python :: 3.6',\n        'Programming Language :: Python :: 3.7',\n        'Topic :: Utilities',\n    ],\n    url='https://github.com/open-mmlab/mmcv',\n    author='Kai Chen',\n    author_email='chenkaidev@gmail.com',\n    setup_requires=['pytest-runner'],\n    tests_require=['pytest'],\n    install_requires=install_requires,\n    ext_modules=EXT_MODULES,\n    cmdclass={'build_ext': build_ext},\n    zip_safe=False)\n", "path": "setup.py"}], "after_files": [{"content": "import platform\nimport sys\nfrom io import open  # for Python 2 (identical to builtin in Python 3)\nfrom setuptools import Extension, find_packages, setup\n\nimport numpy\nfrom Cython.Distutils import build_ext\n\ninstall_requires = [\n    'numpy>=1.11.1', 'pyyaml', 'six', 'addict', 'requests', 'opencv-python',\n    'Cython'\n]\nif sys.version_info < (3, 3):\n    install_requires.append('backports.shutil_get_terminal_size')\nif sys.version_info < (3, 4):\n    install_requires.extend(['enum34', 'pathlib'])\n\n\ndef readme():\n    with open('README.rst', encoding='utf-8') as f:\n        content = f.read()\n    return content\n\n\ndef get_version():\n    version_file = 'mmcv/version.py'\n    with open(version_file, 'r', encoding='utf-8') as f:\n        exec(compile(f.read(), version_file, 'exec'))\n    return locals()['__version__']\n\n\nif platform.system() == 'Darwin':\n    extra_compile_args = ['-stdlib=libc++']\n    extra_link_args = ['-stdlib=libc++']\nelse:\n    extra_compile_args = []\n    extra_link_args = []\n\nEXT_MODULES = [\n    Extension(\n        name='mmcv._ext',\n        sources=[\n            './mmcv/video/optflow_warp/flow_warp.cpp',\n            './mmcv/video/optflow_warp/flow_warp_module.pyx'\n        ],\n        include_dirs=[numpy.get_include()],\n        language='c++',\n        extra_compile_args=extra_compile_args,\n        extra_link_args=extra_link_args,\n    ),\n]\n\nsetup(\n    name='mmcv',\n    version=get_version(),\n    description='Open MMLab Computer Vision Foundation',\n    long_description=readme(),\n    keywords='computer vision',\n    packages=find_packages(),\n    classifiers=[\n        'Development Status :: 4 - Beta',\n        'License :: OSI Approved :: Apache Software License',\n        'Operating System :: OS Independent',\n        'Programming Language :: Python :: 2',\n        'Programming Language :: Python :: 2.7',\n        'Programming Language :: Python :: 3',\n        'Programming Language :: Python :: 3.4',\n        'Programming Language :: Python :: 3.5',\n        'Programming Language :: Python :: 3.6',\n        'Programming Language :: Python :: 3.7',\n        'Topic :: Utilities',\n    ],\n    url='https://github.com/open-mmlab/mmcv',\n    author='Kai Chen',\n    author_email='chenkaidev@gmail.com',\n    setup_requires=['pytest-runner'],\n    tests_require=['pytest'],\n    install_requires=install_requires,\n    ext_modules=EXT_MODULES,\n    cmdclass={'build_ext': build_ext},\n    zip_safe=False)\n", "path": "setup.py"}]}