Merge branch 'master' into NarrowingTypeLen

Author: JelleZijlstra

.gitignore

@@ -10,6 +10,7 @@ mypyc/doc/_build
 *.iml
 /out/
 .venv*/
+venv/
 .mypy_cache/
 .incremental_checker_cache.json
 .cache
@@ -44,6 +45,8 @@ htmlcov
 bin/
 lib/
 include/
+.python-version
+pyvenv.cfg
 
 .tox
 pip-wheel-metadata

docs/source/command_line.rst

@@ -97,7 +97,7 @@ Config file
 
     This flag makes mypy read configuration settings from the given file.
 
-    By default settings are read from ``mypy.ini``, ``.mypy.ini``, or ``setup.cfg``
+    By default settings are read from ``mypy.ini``, ``.mypy.ini``, ``pyproject.toml``, or ``setup.cfg``
     in the current directory. Settings override mypy's built-in defaults and
     command line flags can override settings.
 

docs/source/config_file.rst

@@ -4,8 +4,8 @@ The mypy configuration file
 ===========================
 
 Mypy supports reading configuration settings from a file.  By default
-it uses the file ``mypy.ini`` with a fallback to ``.mypy.ini``, then ``setup.cfg`` in
-the current directory, then ``$XDG_CONFIG_HOME/mypy/config``, then
+it uses the file ``mypy.ini`` with a fallback to ``.mypy.ini``, then ``pyproject.toml``,
+then ``setup.cfg`` in the current directory, then ``$XDG_CONFIG_HOME/mypy/config``, then
 ``~/.config/mypy/config``, and finally ``.mypy.ini`` in the user home directory
 if none of them are found; the :option:`--config-file <mypy --config-file>` command-line flag can be used
 to read a different file instead (see :ref:`config-file-flag`).
@@ -35,7 +35,7 @@ section names in square brackets and flag settings of the form
 `NAME = VALUE`. Comments start with ``#`` characters.
 
 - A section named ``[mypy]`` must be present.  This specifies
-  the global flags. The ``setup.cfg`` file is an exception to this.
+  the global flags.
 
 - Additional sections named ``[mypy-PATTERN1,PATTERN2,...]`` may be
   present, where ``PATTERN1``, ``PATTERN2``, etc., are comma-separated
@@ -885,5 +885,84 @@ These options may only be set in the global section (``[mypy]``).
 
     Controls how much debug output will be generated.  Higher numbers are more verbose.
 
+
+Using a pyproject.toml file
+***************************
+
+Instead of using a ``mypy.ini`` file, a ``pyproject.toml`` file (as specified by
+`PEP 518`_) may be used instead. A few notes on doing so:
+
+* The ``[mypy]`` section should have ``tool.`` prepended to its name:
+
+  * I.e., ``[mypy]`` would become ``[tool.mypy]``
+
+* The module specific sections should be moved into ``[[tool.mypy.overrides]]`` sections:
+
+  * For example, ``[mypy-packagename]`` would become:
+
+.. code-block:: toml
+
+  [[tool.mypy.overrides]]
+  module = 'packagename'
+  ...
+
+* Multi-module specific sections can be moved into a single ``[[tools.mypy.overrides]]`` section with a
+  module property set to an array of modules:
+
+  * For example, ``[mypy-packagename,packagename2]`` would become:
+
+.. code-block:: toml
+
+  [[tool.mypy.overrides]]
+  module = [
+      'packagename',
+      'packagename2'
+  ]
+  ...
+
+* The following care should be given to values in the ``pyproject.toml`` files as compared to ``ini`` files:
+
+  * Strings must be wrapped in double quotes, or single quotes if the string contains special characters
+
+  * Boolean values should be all lower case
+
+Please see the `TOML Documentation`_ for more details and information on 
+what is allowed in a ``toml`` file. See `PEP 518`_ for more information on the layout
+and structure of the ``pyproject.toml`` file.
+  
+Example ``pyproject.toml``
+**************************
+
+Here is an example of a ``pyproject.toml`` file. To use this config file, place it at the root
+of your repo (or append it to the end of an existing ``pyproject.toml`` file) and run mypy.
+
+.. code-block:: toml
+
+    # mypy global options:
+
+    [tool.mypy]
+    python_version = "2.7"
+    warn_return_any = true
+    warn_unused_configs = true
+
+    # mypy per-module options:
+
+    [[tool.mypy.overrides]]
+    module = "mycode.foo.*"
+    disallow_untyped_defs = true
+
+    [[tool.mypy.overrides]]
+    module = "mycode.bar"
+    warn_return_any = false
+
+    [[tool.mypy.overrides]]
+    module = [
+        "somelibrary",
+        "some_other_library"
+    ]
+    ignore_missing_imports = true
+
 .. _lxml: https://pypi.org/project/lxml/
 .. _SQLite: https://www.sqlite.org/
+.. _PEP 518: https://www.python.org/dev/peps/pep-0518/
+.. _TOML Documentation: https://toml.io/

docs/source/error_code_list.rst

@@ -421,6 +421,10 @@ Check TypedDict items [typeddict-item]
 When constructing a ``TypedDict`` object, mypy checks that each key and value is compatible
 with the ``TypedDict`` type that is inferred from the surrounding context.
 
+When getting a ``TypedDict`` item, mypy checks that the key
+exists. When assigning to a ``TypedDict``, mypy checks that both the
+key and the value are valid.
+
 Example:
 
 .. code-block:: python

docs/source/kinds_of_types.rst

@@ -329,7 +329,7 @@ will complain about the possible ``None`` value. You can use
 
 When initializing a variable as ``None``, ``None`` is usually an
 empty place-holder value, and the actual value has a different type.
-This is why you need to annotate an attribute in a cases like the class
+This is why you need to annotate an attribute in cases like the class
 ``Resource`` above:
 
 .. code-block:: python

docs/source/running_mypy.rst

@@ -520,3 +520,17 @@ For example, if you have multiple projects that happen to be
 using the same set of work-in-progress stubs, it could be
 convenient to just have your ``MYPYPATH`` point to a single
 directory containing the stubs.
+
+Directories specific to Python 2 (@python2)
+*******************************************
+
+When type checking in Python 2 mode, mypy also looks for files under
+the ``@python2`` subdirectory of each ``MYPYPATH`` and ``mypy_path``
+entry, if the subdirectory exists. Files under the subdirectory take
+precedence over the parent directory. This can be used to provide
+separate Python 2 versions of stubs.
+
+.. note::
+
+    This does not need to be used (and cannot be used) with
+    :ref:`PEP 561 compliant stub packages <installed-packages>`.

mypy/checker.py

@@ -3961,9 +3961,10 @@ def find_type_equals_check(self, node: ComparisonExpr, expr_indices: List[int]
                                ) -> Tuple[TypeMap, TypeMap]:
         """Narrow types based on any checks of the type ``type(x) == T``
 
-        :param node: The node that might contain the comparison
-
-        :param expr_indices: The list of indices of expressions in ``node`` that are being compared
+        Args:
+            node: The node that might contain the comparison
+            expr_indices: The list of indices of expressions in ``node`` that are being
+                compared
         """
         type_map = self.type_map
 

mypy/checkexpr.py

@@ -77,6 +77,7 @@
                        int,
                        int,
                        CallableType,
+                       Optional[Type],
                        Context,
                        Context,
                        MessageBuilder],
@@ -1011,7 +1012,7 @@ def check_callable_call(self,
                                   arg_names, formal_to_actual, context, self.msg)
 
         self.check_argument_types(arg_types, arg_kinds, args, callee, formal_to_actual, context,
-                                  messages=arg_messages)
+                                  messages=arg_messages, object_type=object_type)
 
         if (callee.is_type_obj() and (len(arg_types) == 1)
                 and is_equivalent(callee.ret_type, self.named_type('builtins.type'))):
@@ -1452,10 +1453,13 @@ def check_argument_types(self,
                              formal_to_actual: List[List[int]],
                              context: Context,
                              messages: Optional[MessageBuilder] = None,
-                             check_arg: Optional[ArgChecker] = None) -> None:
+                             check_arg: Optional[ArgChecker] = None,
+                             object_type: Optional[Type] = None) -> None:
         """Check argument types against a callable type.
 
         Report errors if the argument types are not compatible.
+
+        The check_call docstring describes some of the arguments.
         """
         messages = messages or self.msg
         check_arg = check_arg or self.check_arg
@@ -1480,7 +1484,7 @@ def check_argument_types(self,
                     callee.arg_names[i], callee.arg_kinds[i])
                 check_arg(expanded_actual, actual_type, arg_kinds[actual],
                           callee.arg_types[i],
-                          actual + 1, i + 1, callee, args[actual], context, messages)
+                          actual + 1, i + 1, callee, object_type, args[actual], context, messages)
 
     def check_arg(self,
                   caller_type: Type,
@@ -1490,6 +1494,7 @@ def check_arg(self,
                   n: int,
                   m: int,
                   callee: CallableType,
+                  object_type: Optional[Type],
                   context: Context,
                   outer_context: Context,
                   messages: MessageBuilder) -> None:
@@ -1515,6 +1520,7 @@ def check_arg(self,
                                                   callee,
                                                   original_caller_type,
                                                   caller_kind,
+                                                  object_type=object_type,
                                                   context=context,
                                                   outer_context=outer_context)
             messages.incompatible_argument_note(original_caller_type, callee_type, context,
@@ -1978,6 +1984,7 @@ def check_arg(caller_type: Type,
                       n: int,
                       m: int,
                       callee: CallableType,
+                      object_type: Optional[Type],
                       context: Context,
                       outer_context: Context,
                       messages: MessageBuilder) -> None:
@@ -2439,7 +2446,7 @@ def check_method_call(self,
 
         return self.check_call(method_type, args, arg_kinds,
                                context, arg_messages=local_errors,
-                               callable_name=callable_name, object_type=object_type)
+                               callable_name=callable_name, object_type=base_type)
 
     def check_op_reversible(self,
                             op_name: str,
@@ -2903,9 +2910,11 @@ def visit_index_with_type(self, left_type: Type, e: IndexExpr,
 
         if isinstance(left_type, UnionType):
             original_type = original_type or left_type
+            # Don't combine literal types, since we may need them for type narrowing.
             return make_simplified_union([self.visit_index_with_type(typ, e,
                                                                      original_type)
-                                          for typ in left_type.relevant_items()])
+                                          for typ in left_type.relevant_items()],
+                                         contract_literals=False)
         elif isinstance(left_type, TupleType) and self.chk.in_checked_function():
             # Special case for tuples. They return a more specific type when
             # indexed by an integer literal.