Fix windows linkage in Python grpcio-tools

3 files changed, 35 insertions, 12 deletions

diff --git a/tools/distrib/python/grpcio_tools/README.rst b/tools/distrib/python/grpcio_tools/README.rst
index 3be564ef5b..10d2fe8c30 100644
--- a/tools/distrib/python/grpcio_tools/README.rst
+++ b/tools/distrib/python/grpcio_tools/README.rst
@@ -46,7 +46,9 @@ From Source
 ~~~~~~~~~~~
 
 Building from source requires that you have the Python headers (usually a
-package named :code:`python-dev`) and Cython installed.
+package named :code:`python-dev`) and Cython installed. It further requires a
+GCC-like compiler to go smoothly; you can probably get it to work without
+GCC-like stuff, but you may end up having a bad time.
 
 ::
 
diff --git a/tools/distrib/python/grpcio_tools/setup.py b/tools/distrib/python/grpcio_tools/setup.py
index 0281c01796..98f03c8d64 100644
--- a/tools/distrib/python/grpcio_tools/setup.py
+++ b/tools/distrib/python/grpcio_tools/setup.py
@@ -30,6 +30,7 @@
 from distutils import extension
 import os
 import os.path
+import shlex
 import sys
 
 import setuptools
@@ -40,6 +41,16 @@ from setuptools.command import build_ext
 os.chdir(os.path.dirname(os.path.abspath(__file__)))
 sys.path.insert(0, os.path.abspath('.'))
 
+# There are some situations (like on Windows) where CC, CFLAGS, and LDFLAGS are
+# entirely ignored/dropped/forgotten by distutils and its Cygwin/MinGW support.
+# We use these environment variables to thus get around that without locking
+# ourselves in w.r.t. the multitude of operating systems this ought to build on.
+# By default we assume a GCC-like compiler.
+EXTRA_COMPILE_ARGS = shlex.split(os.environ.get('GRPC_PYTHON_CFLAGS',
+                                                '-frtti -std=c++11'))
+EXTRA_LINK_ARGS = shlex.split(os.environ.get('GRPC_PYTHON_LDFLAGS',
+                                             '-lpthread'))
+
 import protoc_lib_deps
 import grpc_version
 
@@ -60,7 +71,8 @@ def protoc_ext_module():
       ],
       language='c++',
       define_macros=[('HAVE_PTHREAD', 1)],
-      extra_compile_args=['-lpthread', '-frtti', '-std=c++11'],
+      extra_compile_args=EXTRA_COMPILE_ARGS,
+      extra_link_args=EXTRA_LINK_ARGS,
   )
   return plugin_ext
 
diff --git a/tools/run_tests/build_artifact_python.bat b/tools/run_tests/build_artifact_python.bat
index 342469bba8..fea0275426 100644
--- a/tools/run_tests/build_artifact_python.bat
+++ b/tools/run_tests/build_artifact_python.bat
@@ -41,7 +41,7 @@ copy /Y vsprojects\Release\grpc_dll.dll src\python\grpcio\grpc\_cython\_windows\
 copy /Y vsprojects\x64\Release\grpc_dll.dll src\python\grpcio\grpc\_cython\_windows\grpc_c.64.python || goto :error
 
 
-set PATH=C:\%1;C:\%1\scripts;%PATH%
+set PATH=C:\%1;C:\%1\scripts;C:\msys64\mingw%2\bin;%PATH%
 
 pip install --upgrade six
 pip install --upgrade setuptools
@@ -55,19 +55,28 @@ set GRPC_PYTHON_BUILD_WITH_CYTHON=1
 python setup.py bdist_wheel
 
 @rem Build gRPC Python tools
-set PATH=C:\msys64\mingw%2\bin;%PATH%
-set CC=C:\msys64\mingw%2\bin\g++.exe
-set CFLAGS=-fno-wrapv
+@rem
+@rem Because this is windows and *everything seems to hate Windows* we have to
+@rem set all of these flags ourselves because Python won't help us (see the
+@rem setup.py of the grpcio_tools project).
+set GRPC_PYTHON_CFLAGS=-fno-wrapv -frtti -std=c++11
+@rem Further confusing things, MSYS2's mingw64 tries to dynamically link
+@rem libgcc, libstdc++, and winpthreads. We have to override this or our
+@rem extensions end up linking to MSYS2 DLLs, which the normal Python on
+@rem Windows user won't have... and ON TOP OF THIS, there's MinGW's GCC default
+@rem behavior of linking msvcrt.dll as the C runtime library, which we need to
+@rem override so that Python's distutils doesn't link us against multiple C
+@rem runtimes.
+python -c "from distutils.cygwinccompiler import get_msvcr; print(get_msvcr()[0])" > temp.txt
+set /p PYTHON_MSVCR=<temp.txt
+set GRPC_PYTHON_LDFLAGS=-static-libgcc -static-libstdc++ -mcrtdll=%PYTHON_MSVCR% -static -lpthread
 python tools\distrib\python\make_grpcio_tools.py
-@rem The following commands *must* be run with the right version of python
-@rem otherwise the build get SNAFU'd (so we use the .exe suffix to invoke the python
-@rem we set in the %PATH% variable above).
 if %2 == 32 (
-  python.exe tools\distrib\python\grpcio_tools\setup.py build_ext -c mingw32
+  python tools\distrib\python\grpcio_tools\setup.py build_ext -c mingw32
 ) else (
-  python.exe tools\distrib\python\grpcio_tools\setup.py build_ext -c mingw32 -DMS_WIN64
+  python tools\distrib\python\grpcio_tools\setup.py build_ext -c mingw32 -DMS_WIN64
 )
-python.exe tools\distrib\python\grpcio_tools\setup.py bdist_wheel
+python tools\distrib\python\grpcio_tools\setup.py bdist_wheel
 
 mkdir artifacts
 xcopy /Y /I /S dist\* artifacts\ || goto :error