Use some more dogfooding (#7385)

This PR enables `--strict-equality` and `--show-error-codes` for self-check, and adds error codes in some `# type: ignore`s. So far this revealed two issues:
* Both PyCharm and flake8 get crazy about error codes, generating many false positives
* Error codes in `# type: ignore`s don't always work, see #7384

Author: ilevkivskyi

mypy/config_parser.py

@@ -214,7 +214,7 @@ def parse_section(prefix: str, template: Options,
         v = None  # type: Any
         try:
             if ct is bool:
-                v = section.getboolean(key)  # type: ignore  # Until better stub
+                v = section.getboolean(key)  # type: ignore[attr-defined]  # Until better stub
                 if invert:
                     v = not v
             elif callable(ct):

mypy/fastparse.py

@@ -103,7 +103,7 @@ def ast3_parse(source: Union[str, bytes], filename: str, mode: str,
         Constant = Any
 except ImportError:
     try:
-        from typed_ast import ast35  # type: ignore  # noqa: F401
+        from typed_ast import ast35  # type: ignore[attr-defined]  # noqa: F401
     except ImportError:
         print('The typed_ast package is not installed.\n'
               'You can install it with `python3 -m pip install typed-ast`.',
@@ -463,7 +463,7 @@ def translate_module_id(self, id: str) -> str:
         return id
 
     def visit_Module(self, mod: ast3.Module) -> MypyFile:
-        self.type_ignores = {ti.lineno: parse_type_ignore_tag(ti.tag)  # type: ignore
+        self.type_ignores = {ti.lineno: parse_type_ignore_tag(ti.tag)  # type: ignore[attr-defined]
                              for ti in mod.type_ignores}
         body = self.fix_function_overloads(self.translate_stmt_list(mod.body, ismodule=True))
         return MypyFile(body,

mypy/fastparse2.py

@@ -65,7 +65,7 @@
     from mypy.fastparse import ast3, ast3_parse
 except ImportError:
     try:
-        from typed_ast import ast35  # type: ignore  # noqa: F401
+        from typed_ast import ast35  # type: ignore[attr-defined]  # noqa: F401
     except ImportError:
         print('The typed_ast package is not installed.\n'
               'You can install it with `python3 -m pip install typed-ast`.',
@@ -342,7 +342,7 @@ def translate_module_id(self, id: str) -> str:
         return id
 
     def visit_Module(self, mod: ast27.Module) -> MypyFile:
-        self.type_ignores = {ti.lineno: parse_type_ignore_tag(ti.tag)  # type: ignore
+        self.type_ignores = {ti.lineno: parse_type_ignore_tag(ti.tag)  # type: ignore[attr-defined]
                              for ti in mod.type_ignores}
         body = self.fix_function_overloads(self.translate_stmt_list(mod.body))
         return MypyFile(body,

mypy/fscache.py

@@ -137,7 +137,7 @@ def _fake_init(self, path: str) -> os.stat_result:
         st = self.stat(dirname)  # May raise OSError
         # Get stat result as a sequence so we can modify it.
         # (Alas, typeshed's os.stat_result is not a sequence yet.)
-        tpl = tuple(st)  # type: ignore
+        tpl = tuple(st)  # type: ignore[arg-type, var-annotated]
         seq = list(tpl)  # type: List[float]
         seq[stat.ST_MODE] = stat.S_IFREG | 0o444
         seq[stat.ST_INO] = 1

mypy/messages.py

@@ -1552,8 +1552,8 @@ def [T <: int] f(self, x: int, y: T) -> None
             s += ' = ...'
 
     # If we got a "special arg" (i.e: self, cls, etc...), prepend it to the arg list
-    if tp.definition is not None and tp.definition.name() is not None:
-        definition_args = tp.definition.arg_names  # type: ignore
+    if isinstance(tp.definition, FuncDef) and tp.definition.name() is not None:
+        definition_args = tp.definition.arg_names
         if definition_args and tp.arg_names != definition_args \
                 and len(definition_args) > 0:
             if s:

mypy/report.py

@@ -28,7 +28,7 @@
     # mypyc doesn't properly handle import from of submodules that we
     # don't have stubs for, hence the hacky double import
     import lxml.etree  # type: ignore  # noqa: F401
-    from lxml import etree  # type: ignore
+    from lxml import etree
     LXML_INSTALLED = True
 except ImportError:
     LXML_INSTALLED = False

mypy/server/aststrip.py

@@ -115,7 +115,7 @@ def visit_class_def(self, node: ClassDef) -> None:
         node.base_type_exprs.extend(node.removed_base_type_exprs)
         node.removed_base_type_exprs = []
         node.defs.body = [s for s in node.defs.body
-                          if s not in to_delete]
+                          if s not in to_delete]  # type: ignore[comparison-overlap]
         with self.enter_class(node.info):
             super().visit_class_def(node)
         TypeState.reset_subtype_caches_for(node.info)

mypy/types.py

@@ -196,13 +196,13 @@ def expand_all_if_possible(self) -> Optional['ProperType']:
 
     # TODO: remove ignore caused by https://github.com/python/mypy/issues/6759
     @property
-    def can_be_true(self) -> bool:  # type: ignore
+    def can_be_true(self) -> bool:  # type: ignore[override]
         assert self.alias is not None
         return self.alias.target.can_be_true
 
     # TODO: remove ignore caused by https://github.com/python/mypy/issues/6759
     @property
-    def can_be_false(self) -> bool:  # type: ignore
+    def can_be_false(self) -> bool:  # type: ignore[override]
         assert self.alias is not None
         return self.alias.target.can_be_false
 
@@ -1903,7 +1903,7 @@ def make_normalized(item: Type, *, line: int = -1, column: int = -1) -> ProperTy
                 [TypeType.make_normalized(union_item) for union_item in item.items],
                 line=line, column=column
             )
-        return TypeType(item, line=line, column=column)  # type: ignore
+        return TypeType(item, line=line, column=column)  # type: ignore[arg-type]
 
     def accept(self, visitor: 'TypeVisitor[T]') -> T:
         return visitor.visit_type_type(self)

mypy_self_check.ini

@@ -6,11 +6,14 @@ check_untyped_defs = True
 disallow_subclassing_any = True
 warn_no_return = True
 strict_optional = True
+strict_equality = True
 no_implicit_optional = True
 disallow_any_generics = True
 disallow_any_unimported = True
 warn_redundant_casts = True
+warn_unused_ignores = True
 warn_unused_configs = True
 show_traceback = True
+show_error_codes = True
 always_false = MYPYC
 plugins = misc/proper_plugin.py

setup.cfg

@@ -41,7 +41,8 @@ exclude =
 #   B006: use of mutable defaults in function signatures
 #   B007: Loop control variable not used within the loop body.
 #   B011: Don't use assert False
-extend-ignore = E128,W601,E701,E704,E402,B3,B006,B007,B011
+#   F821: Name not defined (generates false positives with error codes)
+extend-ignore = E128,W601,E701,E704,E402,B3,B006,B007,B011,F821
 
 [coverage:run]
 branch = true