Drop support for running with 3.4

mypy/dmypy.py

@@ -18,6 +18,7 @@
 from mypy.dmypy_util import DEFAULT_STATUS_FILE, receive
 from mypy.ipc import IPCClient, IPCException
 from mypy.dmypy_os import alive, kill
+from mypy.util import check_python_version
 
 from mypy.version import __version__
 
@@ -131,6 +132,7 @@ class BadStatus(Exception):
 
 def main(argv: List[str]) -> None:
     """The code is top-down."""
+    check_python_version('dmypy')
     args = parser.parse_args(argv)
     if not args.action:
         parser.print_usage()

mypy/fastparse.py

@@ -98,21 +98,17 @@ def ast3_parse(source: Union[str, bytes], filename: str, mode: str,
         NamedExpr = Any
         Constant = Any
 except ImportError:
-    if sys.version_info.minor > 4:
-        try:
-            from typed_ast import ast35  # type: ignore
-        except ImportError:
-            print('The typed_ast package is not installed.\n'
-                  'You can install it with `python3 -m pip install typed-ast`.',
-                  file=sys.stderr)
-        else:
-            print('You need a more recent version of the typed_ast package.\n'
-                  'You can update to the latest version with '
-                  '`python3 -m pip install -U typed-ast`.',
-                  file=sys.stderr)
+    try:
+        from typed_ast import ast35  # type: ignore
+    except ImportError:
+        print('The typed_ast package is not installed.\n'
+              'You can install it with `python3 -m pip install typed-ast`.',
+              file=sys.stderr)
     else:
-        print('Mypy requires the typed_ast package, which is only compatible with\n'
-              'Python 3.5 and greater.', file=sys.stderr)
+        print('You need a more recent version of the typed_ast package.\n'
+              'You can update to the latest version with '
+              '`python3 -m pip install -U typed-ast`.',
+              file=sys.stderr)
     sys.exit(1)
 
 N = TypeVar('N', bound=Node)

mypy/fastparse2.py

@@ -60,21 +60,17 @@
     # Import ast3 from fastparse, which has special case for Python 3.8
     from mypy.fastparse import ast3, ast3_parse
 except ImportError:
-    if sys.version_info.minor > 4:
-        try:
-            from typed_ast import ast35  # type: ignore
-        except ImportError:
-            print('The typed_ast package is not installed.\n'
-                  'You can install it with `python3 -m pip install typed-ast`.',
-                  file=sys.stderr)
-        else:
-            print('You need a more recent version of the typed_ast package.\n'
-                  'You can update to the latest version with '
-                  '`python3 -m pip install -U typed-ast`.',
-                  file=sys.stderr)
+    try:
+        from typed_ast import ast35  # type: ignore
+    except ImportError:
+        print('The typed_ast package is not installed.\n'
+              'You can install it with `python3 -m pip install typed-ast`.',
+              file=sys.stderr)
     else:
-        print('Mypy requires the typed_ast package, which is only compatible with\n'
-              'Python 3.5 and greater.', file=sys.stderr)
+        print('You need a more recent version of the typed_ast package.\n'
+              'You can update to the latest version with '
+              '`python3 -m pip install -U typed-ast`.',
+              file=sys.stderr)
     sys.exit(1)
 
 N = TypeVar('N', bound=Node)

mypy/main.py

@@ -53,14 +53,7 @@ def main(script_path: Optional[str], args: Optional[List[str]] = None) -> None:
         args: Custom command-line arguments.  If not given, sys.argv[1:] will
         be used.
     """
-    # Check for known bad Python versions.
-    if sys.version_info[:2] < (3, 5):
-        sys.exit("Running mypy with Python 3.4 or lower is not supported; "
-                 "please upgrade to 3.5 or newer")
-    if sys.version_info[:3] == (3, 5, 0):
-        sys.exit("Running mypy with Python 3.5.0 is not supported; "
-                 "please upgrade to 3.5.1 or newer")
-
+    util.check_python_version('mypy')
     t0 = time.time()
     # To log stat() calls: os.stat = stat_proxy
     sys.setrecursionlimit(2 ** 14)

mypy/stubgen.py

@@ -1181,6 +1181,7 @@ def parse_options(args: List[str]) -> Options:
 
 
 def main() -> None:
+    mypy.util.check_python_version('stubgen')
     # Make sure that the current directory is in sys.path so that
     # stubgen can be run on packages in the current directory.
     if not ('' in sys.path or '.' in sys.path):

mypy/util.py

@@ -257,3 +257,15 @@ def hard_exit(status: int = 0) -> None:
 def unmangle(name: str) -> str:
     """Remove internal suffixes from a short name."""
     return name.rstrip("'")
+
+
+def check_python_version(program: str) -> None:
+    """Report issues with the Python used to run mypy, dmypy, or stubgen"""
+    # Check for known bad Python versions.
+    if sys.version_info[:2] < (3, 5):
+        sys.exit("Running {name} with Python 3.4 or lower is not supported; "
+                 "please upgrade to 3.5 or newer".format(name=program))
+    # this can be deleted once we drop support for 3.5
+    if sys.version_info[:3] == (3, 5, 0):
+        sys.exit("Running stubgen with Python 3.5.0 is not supported; "
+                 "please upgrade to 3.5.1 or newer")

tox.ini

@@ -1,8 +1,7 @@
 [tox]
 minversion = 3.5.1
 skip_missing_interpreters = true
-envlist = py34,
-          py35,
+envlist = py35,
           py36,
           py37,
           lint,