Add compiler error diagnostics to Python setup

PYTHON-MANIFEST.in

@@ -5,6 +5,7 @@ graft include/grpc
 graft third_party/boringssl
 include src/python/grpcio/commands.py
 include src/python/grpcio/grpc_core_dependencies.py
+include src/python/grpcio/support.py
 include src/python/grpcio/README.rst
 include requirements.txt
 include etc/roots.pem

setup.py

@@ -48,7 +48,7 @@
 
 # Ensure we're in the proper directory whether or not we're being used by pip.
 os.chdir(os.path.dirname(os.path.abspath(__file__)))
-sys.path.insert(0, PYTHON_STEM)
+sys.path.insert(0, os.path.abspath(PYTHON_STEM))
 
 # Break import-style to ensure we can actually find our in-repo dependencies.
 import commands

src/python/grpcio/commands.py

@@ -37,9 +37,9 @@
 import sys
 
 import setuptools
+from setuptools.command import build_ext
 from setuptools.command import build_py
 from setuptools.command import test
-from setuptools.command import build_ext
 
 PYTHON_STEM = os.path.dirname(os.path.abspath(__file__))
 
@@ -186,7 +186,13 @@ def build_extensions(self):
     if compiler in BuildExt.LINK_OPTIONS:
       for extension in self.extensions:
         extension.extra_link_args += list(BuildExt.LINK_OPTIONS[compiler])
-    build_ext.build_ext.build_extensions(self)
+    try:
+      build_ext.build_ext.build_extensions(self)
+    except KeyboardInterrupt:
+      raise
+    except Exception as error:
+      support.diagnose_build_ext_error(self, error)
+      raise CommandError("Failed `build_ext` step.")
 
 
 class Gather(setuptools.Command):

src/python/grpcio/support.py

@@ -0,0 +1,91 @@
+# Copyright 2016, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * Redistributions in binary form must reproduce the above
+# copyright notice, this list of conditions and the following disclaimer
+# in the documentation and/or other materials provided with the
+# distribution.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+import os
+import os.path
+import shutil
+import sys
+import tempfile
+
+from distutils import errors
+
+import commands
+
+
+C_PYTHON_DEV = """
+#include <Python.h>
+int main(int argc, char **argv) { return 0; }
+"""
+C_PYTHON_DEV_ERROR_MESSAGE = """
+Could not find <Python.h>. This could mean the following:
+  * You're on Ubuntu and haven't `apt-get install`ed `python-dev`.
+  * You're on Mac OS X and the usual Python framework was somehow corrupted
+    (check your environment variables or try re-installing?)
+  * You're on Windows and your Python installation was somehow corrupted
+    (check your environment variables or try re-installing?)
+    * Note: Windows users should look into installing `vcpython27`.
+"""
+
+C_CHECKS = {
+  C_PYTHON_DEV: C_PYTHON_DEV_ERROR_MESSAGE,
+}
+
+def _compile(compiler, source_string):
+  tempdir = tempfile.mkdtemp()
+  cpath = os.path.join(tempdir, 'a.c')
+  with open(cpath, 'w') as cfile:
+    cfile.write(source_string)
+  try:
+    compiler.compile([cpath])
+  except errors.CompileError as error:
+    return error
+  finally:
+    shutil.rmtree(tempdir)
+
+def _expect_compile(compiler, source_string, error_message):
+  if _compile(compiler, source_string) is not None:
+    sys.stderr.write(error_message)
+    raise commands.CommandError(
+        "Diagnostics found a compilation environment issue:\n{}"
+            .format(error_message))
+
+def diagnose_build_ext_error(build_ext, error):
+  {
+      errors.CompileError: diagnose_compile_error
+  }[type(error)](build_ext, error)
+
+def diagnose_compile_error(build_ext, error):
+  """Attempt to run a few test files through the compiler to see if we can
+     diagnose the reason for the compile failure."""
+  for c_check, message in C_CHECKS.items():
+    _expect_compile(build_ext.compiler, c_check, message)
+  raise commands.CommandError(
+      "\n\nWe could not diagnose your build failure. Please file an issue at "
+      "http://www.github.com/grpc/grpc with `[Python install]` in the title.")