Remove --fast-parser flag from mypy

Author: ddfisher

README.md

@@ -116,8 +116,9 @@ this:
 
     $ python3 -m pip install -U mypy
 
-Except on Windows, it's best to always use the `--fast-parser`
-option to mypy; this requires installing `typed-ast`:
+This should automatically installed the appropriate version of
+mypy's parser, typed-ast.  If for some reason it does not, you
+can install it manually:
 
     $ python3 -m pip install -U typed-ast
 

docs/source/command_line.rst

@@ -15,7 +15,7 @@ flag (or its long form ``--help``)::
               [--check-untyped-defs] [--disallow-subclassing-any]
               [--warn-incomplete-stub] [--warn-redundant-casts]
               [--warn-no-return] [--warn-unused-ignores] [--show-error-context]
-              [--fast-parser] [-i] [--cache-dir DIR] [--strict-optional]
+              [-i] [--cache-dir DIR] [--strict-optional]
               [--strict-optional-whitelist [GLOB [GLOB ...]]] [--strict]
               [--junit-xml JUNIT_XML] [--pdb] [--show-traceback] [--stats]
               [--inferstats] [--custom-typing MODULE]
@@ -303,10 +303,6 @@ Here are some more useful flags:
   to speed up type checking. Incremental mode can help when most parts
   of your program haven't changed since the previous mypy run.
 
-- ``--fast-parser`` enables an experimental parser implemented in C that
-  is faster than the default parser and supports multi-line comment
-  function annotations (see :ref:`multi_line_annotation` for the details).
-
 - ``--python-version X.Y`` will make mypy typecheck your code as if it were
   run under Python version X.Y. Without this option, mypy will default to using
   whatever version of Python is running mypy. Note that the ``-2`` and

docs/source/config_file.rst

@@ -93,9 +93,6 @@ The following global flags may only be set in the global section
 - ``dump_inference_stats`` (Boolean, default False) dumps stats about
   type inference.
 
-- ``fast_parser`` (Boolean, default False) enables the experimental
-  fast parser.
-
 - ``incremental`` (Boolean, default False) enables the experimental
   module cache.
 

docs/source/kinds_of_types.rst

@@ -691,12 +691,6 @@ Mypy supports it already:
 
     p = Point(x=1, y='x')  # Argument has incompatible type "str"; expected "int"
 
-.. note::
-
-   The Python 3.6 syntax requires the ``--fast-parser`` flag. You must also have the
-   `typed_ast <https://pypi.python.org/pypi/typed-ast>`_ package
-   installed and have at least version 0.6.1.  Use ``pip3 install -U typed_ast``.
-
 .. _type-of-class:
 
 The type of class objects
@@ -872,15 +866,6 @@ annotated the first example as the following:
 Typing async/await
 ******************
 
-.. note::
-
-   Currently, you must pass in the ``--fast-parser`` flag if you want to run
-   mypy against code containing the ``async/await`` keywords. The fast parser
-   will be enabled by default in a future version of mypy.
-
-   Note that mypy will understand coroutines created using the ``@asyncio.coroutine``
-   decorator both with and without the fast parser enabled.
-
 Mypy supports the ability to type coroutines that use the ``async/await``
 syntax introduced in Python 3.5. For more information regarding coroutines and
 this new syntax, see `PEP 492 <https://www.python.org/dev/peps/pep-0492/>`_.

docs/source/python2.rst

@@ -66,12 +66,6 @@ overly long type comments and it's often tricky to see which argument
 type corresponds to which argument. The alternative, multi-line
 annotation syntax makes long annotations easier to read and write.
 
-.. note::
-
-    Multi-line comment annotations currently only work when using the
-    ``--fast-parser`` command line option.  This is not enabled by
-    default because the option isn’t supported on Windows yet.
-
 Here is an example (from PEP 484):
 
 .. code-block:: python

mypy/checker.py

@@ -1836,9 +1836,8 @@ def visit_assert_stmt(self, s: AssertStmt) -> None:
         if s.msg is not None:
             self.expr_checker.accept(s.msg)
 
-        if self.options.fast_parser:
-            if isinstance(s.expr, TupleExpr) and len(s.expr.items) > 0:
-                self.warn(messages.MALFORMED_ASSERT, s)
+        if isinstance(s.expr, TupleExpr) and len(s.expr.items) > 0:
+            self.warn(messages.MALFORMED_ASSERT, s)
 
         # If this is asserting some isinstance check, bind that type in the following code
         true_map, _ = self.find_isinstance_check(s.expr)

mypy/main.py

@@ -236,8 +236,6 @@ def add_invertible_flag(flag: str,
     add_invertible_flag('--show-error-context', default=False,
                         dest='show_error_context',
                         help='Precede errors with "note:" messages explaining context')
-    add_invertible_flag('--no-fast-parser', default=True, dest='fast_parser',
-                        help="disable the fast parser (not recommended)")
     parser.add_argument('-i', '--incremental', action='store_true',
                         help="enable module cache")
     parser.add_argument('--quick-and-dirty', action='store_true',
@@ -306,6 +304,11 @@ def add_invertible_flag(flag: str,
     parser.add_argument('--almost-silent', action='store_true',
                         dest='special-opts:almost_silent',
                         help=argparse.SUPPRESS)
+    parser.add_argument('--fast-parser', action='store_true', dest='special-opts:fast_parser',
+                        help=argparse.SUPPRESS)
+    parser.add_argument('--no-fast-parser', action='store_true',
+                        dest='special-opts:no_fast_parser',
+                        help=argparse.SUPPRESS)
 
     report_group = parser.add_argument_group(
         title='report generation',
@@ -376,6 +379,11 @@ def add_invertible_flag(flag: str,
         print("Warning: -f/--dirty-stubs is deprecated and no longer necessary. Mypy no longer "
               "checks the git status of stubs.",
               file=sys.stderr)
+    if special_opts.fast_parser:
+        print("Warning: --fast-parser is now the default (and only) parser.")
+    if special_opts.no_fast_parser:
+        print("Warning: --no-fast-parser no longer has any effect.  The fast parser "
+              "is now mypy's default and only parser.")
 
     # Check for invalid argument combinations.
     if require_targets:

mypy/options.py

@@ -101,9 +101,6 @@ def __init__(self) -> None:
         # Write junit.xml to given file
         self.junit_xml = None  # type: Optional[str]
 
-        # Fast parser is on by default
-        self.fast_parser = True
-
         # Caching options
         self.incremental = False
         self.cache_dir = defaults.CACHE_DIR

mypy/stubgen.py

@@ -73,15 +73,13 @@
                                  ('modules', List[str]),
                                  ('ignore_errors', bool),
                                  ('recursive', bool),
-                                 ('fast_parser', bool),
                                  ])
 
 
 def generate_stub_for_module(module: str, output_dir: str, quiet: bool = False,
                              add_header: bool = False, sigs: Dict[str, str] = {},
                              class_sigs: Dict[str, str] = {},
                              pyversion: Tuple[int, int] = defaults.PYTHON3_VERSION,
-                             fast_parser: bool = False,
                              no_import: bool = False,
                              search_path: List[str] = [],
                              interpreter: str = sys.executable) -> None:
@@ -109,7 +107,7 @@ def generate_stub_for_module(module: str, output_dir: str, quiet: bool = False,
         target = os.path.join(output_dir, target)
         generate_stub(module_path, output_dir, module_all,
                       target=target, add_header=add_header, module=module,
-                      pyversion=pyversion, fast_parser=fast_parser)
+                      pyversion=pyversion)
     if not quiet:
         print('Created %s' % target)
 
@@ -174,13 +172,12 @@ def load_python_module_info(module: str, interpreter: str) -> Tuple[str, Optiona
 
 def generate_stub(path: str, output_dir: str, _all_: Optional[List[str]] = None,
                   target: str = None, add_header: bool = False, module: str = None,
-                  pyversion: Tuple[int, int] = defaults.PYTHON3_VERSION,
-                  fast_parser: bool = False) -> None:
+                  pyversion: Tuple[int, int] = defaults.PYTHON3_VERSION
+                  ) -> None:
     with open(path, 'rb') as f:
         source = f.read()
     options = MypyOptions()
     options.python_version = pyversion
-    options.fast_parser = fast_parser
     try:
         ast = mypy.parse.parse(source, fnam=path, errors=None, options=options)
     except mypy.errors.CompileError as e:
@@ -623,7 +620,6 @@ def main() -> None:
                                      sigs=sigs,
                                      class_sigs=class_sigs,
                                      pyversion=options.pyversion,
-                                     fast_parser=options.fast_parser,
                                      no_import=options.no_import,
                                      search_path=options.search_path,
                                      interpreter=options.interpreter)
@@ -643,7 +639,6 @@ def parse_options() -> Options:
     doc_dir = ''
     search_path = []  # type: List[str]
     interpreter = ''
-    fast_parser = False
     while args and args[0].startswith('-'):
         if args[0] == '--doc-dir':
             doc_dir = args[1]
@@ -658,8 +653,6 @@ def parse_options() -> Options:
             args = args[1:]
         elif args[0] == '--recursive':
             recursive = True
-        elif args[0] == '--fast-parser':
-            fast_parser = True
         elif args[0] == '--ignore-errors':
             ignore_errors = True
         elif args[0] == '--py2':
@@ -682,8 +675,7 @@ def parse_options() -> Options:
                    interpreter=interpreter,
                    modules=args,
                    ignore_errors=ignore_errors,
-                   recursive=recursive,
-                   fast_parser=fast_parser)
+                   recursive=recursive)
 
 
 def default_python2_interpreter() -> str:
@@ -711,7 +703,6 @@ def usage() -> None:
         Options:
           --py2           run in Python 2 mode (default: Python 3 mode)
           --recursive     traverse listed modules to generate inner package modules as well
-          --fast-parser   enable experimental fast parser
           --ignore-errors ignore errors when trying to generate stubs for modules
           --no-import     don't import the modules, just parse and analyze them
                           (doesn't work with C extension modules and doesn't

mypy/test/testcheck.py

@@ -26,8 +26,6 @@
 
 # List of files that contain test case descriptions.
 files = [
-]
-fast_parser_files = [
     'check-basic.test',
     'check-callable.test',
     'check-classes.test',
@@ -77,8 +75,6 @@
     'check-classvar.test',
 ]
 
-files.extend(fast_parser_files)
-
 
 class TypeCheckSuite(DataSuite):
     def __init__(self, *, update_data: bool = False) -> None:
@@ -157,8 +153,6 @@ def run_case_once(self, testcase: DataDrivenTestCase, incremental: int = 0) -> N
             options.strict_optional = True
         if incremental:
             options.incremental = True
-        if os.path.split(testcase.file)[1] in fast_parser_files:
-            options.fast_parser = True
 
         sources = []
         for module_name, program_path, program_text in module_data: