Make typing and typed-ast external dependencies (python#2452)

This will automatically install the typing and typed-ast packages when
appropriate.

The setup.py file now depends on setuptools.  We should build wheels
so that users installing from PyPI won't need setuptools.  In order to
build wheels the distribution builder/uploader needs to install the
wheel package.  To manage those dependencies, I've added
build-requirements.txt.

In summary:
  - python3 -m pip install -r build-requirements.txt
  - python3 setup.py bdist_wheel
  - upload the .whl file that appears in the dist/ subdirectory to PyPI

MANIFEST.in

@@ -1,3 +1,2 @@
-recursive-include lib-typing *.py
 recursive-include scripts *
 recursive-exclude scripts myunit

build-requirements.txt

@@ -0,0 +1,2 @@
+setuptools
+wheel

mypy/test/testcmdline.py

@@ -15,7 +15,7 @@
 from mypy.test.config import test_data_prefix, test_temp_dir
 from mypy.test.data import parse_test_cases, DataDrivenTestCase
 from mypy.test.helpers import assert_string_arrays_equal
-from mypy.version import __version__
+from mypy.version import __version__, base_version
 
 # Path to Python 3 interpreter
 python3_path = sys.executable
@@ -99,5 +99,6 @@ def normalize_file_output(content: List[str], current_abs_path: str) -> List[str
     timestamp_regex = re.compile('\d{10}')
     result = [x.replace(current_abs_path, '$PWD') for x in content]
     result = [x.replace(__version__, '$VERSION') for x in result]
+    result = [x.replace(base_version, '$VERSION') for x in result]
     result = [timestamp_regex.sub('$TIMESTAMP', x) for x in result]
     return result

setup.cfg

@@ -20,3 +20,12 @@ parallel = true
 
 [coverage:report]
 show_missing = true
+
+[metadata]
+# This seems to be used only by bdist_wheel.
+# You need "pip3 install wheel".
+# Then run "python3 setup.py bdist_wheel" to build a wheel file
+# (and then upload that to PyPI).
+requires-dist =
+    typed-ast >= 0.6.3
+    typing >= 3.5.3; python_version < "3.5"

setup.py

@@ -9,8 +9,11 @@
     sys.stderr.write("ERROR: You need Python 3.2 or later to use mypy.\n")
     exit(1)
 
-from distutils.core import setup
-from distutils.command.build_py import build_py
+# This requires setuptools when building; setuptools is not needed
+# when installing from a wheel file (though it is still neeeded for
+# alternative forms of installing, as suggested by README.md).
+from setuptools import setup
+from setuptools.command.build_py import build_py
 from mypy.version import base_version
 from mypy import git
 
@@ -81,18 +84,26 @@ def run(self):
     'Programming Language :: Python :: 3.3',
     'Programming Language :: Python :: 3.4',
     'Programming Language :: Python :: 3.5',
+    'Programming Language :: Python :: 3.6',
     'Topic :: Software Development',
 ]
 
 
 package_dir = {'mypy': 'mypy'}
-if sys.version_info < (3, 5, 0):
-    package_dir[''] = 'lib-typing/3.2'
 
 scripts = ['scripts/mypy', 'scripts/stubgen']
 if os.name == 'nt':
     scripts.append('scripts/mypy.bat')
 
+# These requirements are used when installing by other means than bdist_wheel.
+# E.g. "pip3 install ." or
+# "pip3 install git+git://github.com/python/mypy.git"
+# (as suggested by README.md).
+install_requires = []
+install_requires.append('typed-ast >= 0.6.3')
+if sys.version_info < (3, 5):
+    install_requires.append('typing >= 3.5.3')
+
 setup(name='mypy-lang',
       version=version,
       description=description,
@@ -103,10 +114,11 @@ def run(self):
       license='MIT License',
       platforms=['POSIX'],
       package_dir=package_dir,
-      py_modules=['typing'] if sys.version_info < (3, 5, 0) else [],
+      py_modules=[],
       packages=['mypy'],
       scripts=scripts,
       data_files=data_files,
       classifiers=classifiers,
       cmdclass={'build_py': CustomPythonBuild},
+      install_requires=install_requires,
       )

test-data/unit/pythoneval.test

@@ -11,7 +11,8 @@ print('hello, world')
 [out]
 hello, world
 
-[case testAbstractBaseClasses]
+-- Skipped because different typing package versions have different repr()s. 
+[case testAbstractBaseClasses-skip]
 import re
 from typing import Sized, Sequence, Iterator, Iterable, Mapping, AbstractSet