Convert MessageBuilder.disable_errors to a context manager

mypy/backports.py

@@ -0,0 +1,18 @@
+import sys
+from contextlib import contextmanager
+from typing import Iterator
+
+if sys.version_info < (3, 6):
+    from collections import OrderedDict as OrderedDict  # noqa: F401
+else:
+    # OrderedDict is kind of slow, so for most of our uses in Python 3.6
+    # and later we'd rather just use dict
+    OrderedDict = dict
+
+
+if sys.version_info < (3, 7):
+    @contextmanager
+    def nullcontext() -> Iterator[None]:
+        yield
+else:
+    from contextlib import nullcontext as nullcontext  # noqa: F401

mypy/checker.py

@@ -1995,10 +1995,9 @@ def is_raising_or_empty(self, s: Statement) -> bool:
             if isinstance(s.expr, EllipsisExpr):
                 return True
             elif isinstance(s.expr, CallExpr):
-                self.expr_checker.msg.disable_errors()
-                typ = get_proper_type(self.expr_checker.accept(
-                    s.expr, allow_none_return=True, always_allow_any=True))
-                self.expr_checker.msg.enable_errors()
+                with self.expr_checker.msg.disable_errors():
+                    typ = get_proper_type(self.expr_checker.accept(
+                        s.expr, allow_none_return=True, always_allow_any=True))
 
                 if isinstance(typ, UninhabitedType):
                     return True
@@ -3050,14 +3049,13 @@ def check_member_assignment(self, instance_type: Type, attribute_type: Type,
         # For non-overloaded setters, the result should be type-checked like a regular assignment.
         # Hence, we first only try to infer the type by using the rvalue as type context.
         type_context = rvalue
-        self.msg.disable_errors()
-        _, inferred_dunder_set_type = self.expr_checker.check_call(
-            dunder_set_type,
-            [TempNode(instance_type, context=context), type_context],
-            [nodes.ARG_POS, nodes.ARG_POS],
-            context, object_type=attribute_type,
-            callable_name=callable_name)
-        self.msg.enable_errors()
+        with self.msg.disable_errors():
+            _, inferred_dunder_set_type = self.expr_checker.check_call(
+                dunder_set_type,
+                [TempNode(instance_type, context=context), type_context],
+                [nodes.ARG_POS, nodes.ARG_POS],
+                context, object_type=attribute_type,
+                callable_name=callable_name)
 
         # And now we in fact type check the call, to show errors related to wrong arguments
         # count, etc., replacing the type context for non-overloaded setters only.

mypy/checkexpr.py

@@ -1,6 +1,6 @@
 """Expression type checker. This file is conceptually part of TypeChecker."""
 
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict, nullcontext
 from contextlib import contextmanager
 import itertools
 from typing import (
@@ -865,12 +865,11 @@ def check_union_call_expr(self, e: CallExpr, object_type: UnionType, member: str
         res = []  # type: List[Type]
         for typ in object_type.relevant_items():
             # Member access errors are already reported when visiting the member expression.
-            self.msg.disable_errors()
-            item = analyze_member_access(member, typ, e, False, False, False,
-                                         self.msg, original_type=object_type, chk=self.chk,
-                                         in_literal_context=self.is_literal_context(),
-                                         self_type=typ)
-            self.msg.enable_errors()
+            with self.msg.disable_errors():
+                item = analyze_member_access(member, typ, e, False, False, False,
+                                             self.msg, original_type=object_type, chk=self.chk,
+                                             in_literal_context=self.is_literal_context(),
+                                             self_type=typ)
             narrowed = self.narrow_type_from_binder(e.callee, item, skip_non_overlapping=True)
             if narrowed is None:
                 continue
@@ -1203,12 +1202,9 @@ def infer_function_type_arguments(self, callee_type: CallableType,
             # due to partial available context information at this time, but
             # these errors can be safely ignored as the arguments will be
             # inferred again later.
-            self.msg.disable_errors()
-
-            arg_types = self.infer_arg_types_in_context(
-                callee_type, args, arg_kinds, formal_to_actual)
-
-            self.msg.enable_errors()
+            with self.msg.disable_errors():
+                arg_types = self.infer_arg_types_in_context(
+                    callee_type, args, arg_kinds, formal_to_actual)
 
             arg_pass_nums = self.get_arg_infer_passes(
                 callee_type.arg_types, formal_to_actual, len(args))
@@ -2798,10 +2794,6 @@ def check_boolean_op(self, e: OpExpr, context: Context) -> Type:
             if left_map is None:
                 self.msg.redundant_left_operand(e.op, e.left)
 
-        # If right_map is None then we know mypy considers the right branch
-        # to be unreachable and therefore any errors found in the right branch
-        # should be suppressed.
-        #
         # Note that we perform these checks *before* we take into account
         # the analysis from the semanal phase below. We assume that nodes
         # marked as unreachable during semantic analysis were done so intentionally.
@@ -2815,13 +2807,11 @@ def check_boolean_op(self, e: OpExpr, context: Context) -> Type:
         elif e.right_always:
             left_map = None
 
-        if right_map is None:
-            self.msg.disable_errors()
-        try:
+        # If right_map is None then we know mypy considers the right branch
+        # to be unreachable and therefore any errors found in the right branch
+        # should be suppressed.
+        with (self.msg.disable_errors() if right_map is None else nullcontext()):
             right_type = self.analyze_cond_branch(right_map, e.right, left_type)
-        finally:
-            if right_map is None:
-                self.msg.enable_errors()
 
         if right_map is None:
             # The boolean expression is statically known to be the left value

mypy/checkmember.py

@@ -268,7 +268,7 @@ def analyze_type_type_member_access(name: str,
     item = None
     fallback = mx.builtin_type('builtins.type')
     ignore_messages = mx.msg.copy()
-    ignore_messages.disable_errors()
+    ignore_messages.disable_errors().__enter__()
     if isinstance(typ.item, Instance):
         item = typ.item
     elif isinstance(typ.item, AnyType):

mypy/errors.py

@@ -1,7 +1,7 @@
 import os.path
 import sys
 import traceback
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 from collections import defaultdict
 
 from typing import Tuple, List, TypeVar, Set, Dict, Optional, TextIO, Callable

mypy/join.py

@@ -1,6 +1,6 @@
 """Calculation of the least upper bound types (joins)."""
 
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 from typing import List, Optional
 
 from mypy.types import (

mypy/meet.py

@@ -1,4 +1,4 @@
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 from typing import List, Optional, Tuple, Callable
 
 from mypy.join import (

mypy/messages.py

@@ -8,13 +8,14 @@
 Historically we tried to avoid all message string literals in the type
 checker but we are moving away from this convention.
 """
+from contextlib import contextmanager
 
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 import re
 import difflib
 from textwrap import dedent
 
-from typing import cast, List, Dict, Any, Sequence, Iterable, Tuple, Set, Optional, Union
+from typing import cast, List, Dict, Any, Sequence, Iterable, Iterator, Tuple, Set, Optional, Union
 from typing_extensions import Final
 
 from mypy.erasetype import erase_type
@@ -136,11 +137,13 @@ def add_errors(self, messages: 'MessageBuilder') -> None:
                 for info in errs:
                     self.errors.add_error_info(info)
 
-    def disable_errors(self) -> None:
+    @contextmanager
+    def disable_errors(self) -> Iterator[None]:
         self.disable_count += 1
-
-    def enable_errors(self) -> None:
-        self.disable_count -= 1
+        try:
+            yield
+        finally:
+            self.disable_count -= 1
 
     def is_errors(self) -> bool:
         return self.errors.is_errors()

mypy/nodes.py

@@ -2,7 +2,7 @@
 
 import os
 from abc import abstractmethod
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 from collections import defaultdict
 from typing import (
     Any, TypeVar, List, Tuple, cast, Set, Dict, Union, Optional, Callable, Sequence, Iterator

mypy/nullcontext.py

@@ -0,0 +1,10 @@
+import sys
+from contextlib import contextmanager
+from typing import Iterator
+
+if sys.version_info < (3, 7):
+    @contextmanager
+    def nullcontext() -> Iterator[None]:
+        yield
+else:
+    from contextlib import nullcontext as nullcontext, contextmanager  # noqa: F401

mypy/options.py

@@ -1,4 +1,4 @@
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 import re
 import pprint
 import sys

mypy/ordered_dict.py

@@ -1,9 +0,0 @@
-# OrderedDict is kind of slow, so for most of our uses in Python 3.6
-# and later we'd rather just use dict
-
-import sys
-
-if sys.version_info < (3, 6):
-    from collections import OrderedDict as OrderedDict
-else:
-    OrderedDict = dict

mypy/plugins/attrs.py

@@ -1,6 +1,6 @@
 """Plugin for supporting the attrs library (http://www.attrs.org)"""
 
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 
 from typing import Optional, Dict, List, cast, Tuple, Iterable
 from typing_extensions import Final

mypy/semanal_typeddict.py

@@ -1,6 +1,6 @@
 """Semantic analysis of TypedDict definitions."""
 
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 from typing import Optional, List, Set, Tuple
 from typing_extensions import Final
 

mypy/type_visitor.py

@@ -12,7 +12,7 @@
 """
 
 from abc import abstractmethod
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 from typing import Generic, TypeVar, cast, Any, List, Callable, Iterable, Optional, Set, Sequence
 from mypy_extensions import trait, mypyc_attr
 

mypy/typeanal.py

@@ -3,7 +3,7 @@
 import itertools
 from itertools import chain
 from contextlib import contextmanager
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 
 from typing import Callable, List, Optional, Set, Tuple, Iterator, TypeVar, Iterable, Sequence
 from typing_extensions import Final

mypy/types.py

@@ -3,7 +3,7 @@
 import copy
 import sys
 from abc import abstractmethod
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 
 from typing import (
     Any, TypeVar, Dict, List, Tuple, cast, Set, Optional, Union, Iterable, NamedTuple,

mypyc/codegen/emit.py

@@ -1,6 +1,6 @@
 """Utilities for emitting C code."""
 
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 from typing import List, Set, Dict, Optional, Callable, Union, Tuple
 import sys
 

mypyc/codegen/emitclass.py

@@ -2,7 +2,7 @@
 
 from typing import Optional, List, Tuple, Dict, Callable, Mapping, Set
 
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 
 from mypyc.common import PREFIX, NATIVE_PREFIX, REG_PREFIX, use_fastcall
 from mypyc.codegen.emit import Emitter, HeaderDeclaration

mypyc/codegen/emitmodule.py

@@ -5,7 +5,7 @@
 
 import os
 import json
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 from typing import List, Tuple, Dict, Iterable, Set, TypeVar, Optional
 
 from mypy.nodes import MypyFile

mypyc/ir/class_ir.py

@@ -1,7 +1,7 @@
 """Intermediate representation of classes."""
 
 from typing import List, Optional, Set, Tuple, Dict, NamedTuple
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 
 from mypyc.common import JsonDict
 from mypyc.ir.ops import Value, DeserMaps

mypyc/irbuild/builder.py

@@ -13,7 +13,7 @@
 
 from typing import Callable, Dict, List, Tuple, Optional, Union, Sequence, Set, Any
 from typing_extensions import overload
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 
 from mypy.build import Graph
 from mypy.nodes import (

mypyc/irbuild/main.py

@@ -20,7 +20,7 @@ def f(x: int) -> int:
 below, mypyc.irbuild.builder, and mypyc.irbuild.visitor.
 """
 
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 from typing import List, Dict, Callable, Any, TypeVar, cast
 
 from mypy.nodes import MypyFile, Expression, ClassDef

mypyc/test/test_emitfunc.py

@@ -2,7 +2,7 @@
 
 from typing import List, Optional
 
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 
 from mypy.test.helpers import assert_string_arrays_equal
 

mypyc/test/test_serialization.py

@@ -4,7 +4,7 @@
 # contain its own tests so that pytest will rewrite the asserts...
 
 from typing import Any, Dict, Tuple
-from mypy.ordered_dict import OrderedDict
+from mypy.backports import OrderedDict
 from collections.abc import Iterable
 
 from mypyc.ir.ops import DeserMaps