From a480e644cc2f4a943ed372281e52f345cc32250e Mon Sep 17 00:00:00 2001
From: Denis Gantsev <gantsevdenis@gmail.com>
Date: Sun, 3 Nov 2019 23:56:32 +0100
Subject: [PATCH 1/7] custom type narrower
---
mypy/checker.py | 28 ++++++++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)
diff --git a/mypy/checker.py b/mypy/checker.py
index 7cc1b04b5d91..d8640799e8f4 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -162,7 +162,12 @@ class TypeChecker(NodeVisitor[None], CheckerPluginInterface):
binder = None # type: ConditionalTypeBinder
# Helper for type checking expressions
expr_checker = None # type: mypy.checkexpr.ExpressionChecker
-
+ # temporary container for ctn
+ ctns_queue = None # type:List[str]
+ # uniqueness check for ctn
+ ctns_keys = None # type:Set[str]
+ # custom type narrowers
+ ctns = None # type:List[Tuple[str, Expression]]
tscope = None # type: Scope
scope = None # type: CheckerScope
# Stack of function return types
@@ -231,6 +236,9 @@ def __init__(self, errors: Errors, modules: Dict[str, MypyFile], options: Option
self.type_map = {}
self.module_refs = set()
self.pass_num = 0
+ self.ctns_queue = []
+ self.ctns_keys = set()
+ self.ctns = []
self.current_node_deferred = False
self.is_stub = tree.is_stub
self.is_typeshed_stub = errors.is_typeshed_file(path)
@@ -3379,6 +3387,11 @@ def visit_decorator(self, e: Decorator) -> None:
e.var.type = AnyType(TypeOfAny.special_form)
e.var.is_ready = True
return
+ elif isinstance(d, CallExpr):
+ assert isinstance(d.callee, RefExpr)
+ if d.callee.fullname == 'mypy.extern.narrow_cast':
+ # this function is a CTN
+ self.ctns_queue.append(e.func.fullname()) # type will be added later
if self.recurse_into_functions:
with self.tscope.function_scope(e.func):
@@ -3702,6 +3715,16 @@ def find_isinstance_check(self, node: Expression
elif is_false_literal(node):
return None, {}
elif isinstance(node, CallExpr):
+ expr = None
+ vartype = None
+ type = None
+ for name, expr_ in self.ctns:
+ if refers_to_fullname(node.callee, name):
+ expr = node.args[0]
+ if literal(expr_) == LITERAL_TYPE:
+ vartype = type_map[node.args[0]]
+ type = get_isinstance_type(expr_, type_map)
+ break # name is unique
if refers_to_fullname(node.callee, 'builtins.isinstance'):
if len(node.args) != 2: # the error will be reported elsewhere
return {}, {}
@@ -3709,7 +3732,8 @@ def find_isinstance_check(self, node: Expression
if literal(expr) == LITERAL_TYPE:
vartype = type_map[expr]
type = get_isinstance_type(node.args[1], type_map)
- return conditional_type_map(expr, vartype, type)
+ if expr and vartype and type:
+ return conditional_type_map(expr, vartype, type)
elif refers_to_fullname(node.callee, 'builtins.issubclass'):
if len(node.args) != 2: # the error will be reported elsewhere
return {}, {}
From 4c66b10e5c74bb4212259d2f87d724fbf9131630 Mon Sep 17 00:00:00 2001
From: Denis Gantsev <gantsevdenis@gmail.com>
Date: Mon, 4 Nov 2019 01:40:59 +0100
Subject: [PATCH 2/7] custom narrower
---
mypy/checkexpr.py | 14 +++++++++++---
mypy/extern.py | 10 ++++++++++
2 files changed, 21 insertions(+), 3 deletions(-)
create mode 100644 mypy/extern.py
diff --git a/mypy/checkexpr.py b/mypy/checkexpr.py
index 27f462b7d00f..f8abfcc1e515 100644
--- a/mypy/checkexpr.py
+++ b/mypy/checkexpr.py
@@ -270,9 +270,12 @@ def visit_call_expr_inner(self, e: CallExpr, allow_none_return: bool = False) ->
typeddict_type = e.callee.node.typeddict_type.copy_modified(
fallback=Instance(e.callee.node, []))
return self.check_typeddict_call(typeddict_type, e.arg_kinds, e.arg_names, e.args, e)
- if (isinstance(e.callee, NameExpr) and e.callee.name in ('isinstance', 'issubclass')
- and len(e.args) == 2):
- for typ in mypy.checker.flatten(e.args[1]):
+ if (isinstance(e.callee, NameExpr)
+ and ((e.callee.name in ('isinstance', 'issubclass') and len(e.args) == 2)
+ or e.callee.name == 'narrow_cast' and len(e.args) == 1)):
+ is_narrow_cast = e.callee.name == 'narrow_cast'
+ arg = e.args[1] if not is_narrow_cast else e.args[0]
+ for typ in mypy.checker.flatten(arg):
node = None
if isinstance(typ, NameExpr):
try:
@@ -297,6 +300,11 @@ def visit_call_expr_inner(self, e: CallExpr, allow_none_return: bool = False) ->
self.msg.cannot_use_function_with_type(e.callee.name, "TypedDict", e)
elif typ.node.is_newtype:
self.msg.cannot_use_function_with_type(e.callee.name, "NewType", e)
+ if is_narrow_cast:
+ ctn_name = self.chk.ctns_queue.pop()
+ if ctn_name not in self.chk.ctns_keys:
+ self.chk.ctns.append((ctn_name, arg))
+ self.chk.ctns_keys.add(ctn_name)
self.try_infer_partial_type(e)
type_context = None
if isinstance(e.callee, LambdaExpr):
diff --git a/mypy/extern.py b/mypy/extern.py
new file mode 100644
index 000000000000..973c42a9fd23
--- /dev/null
+++ b/mypy/extern.py
@@ -0,0 +1,10 @@
+from typing import Union, Tuple, Any, Callable
+
+
+# copy pasted from typeshed
+def narrow_cast(T: Union[type, Tuple[Union[type, Tuple[Any, ...]], ...]]) \
+ -> Callable[..., Callable[..., bool]]:
+ def narrow_cast_inner(f: Callable[..., bool]) -> Callable[..., bool]:
+ return f # binds first argument of f to T
+
+ return narrow_cast_inner
From 1e4e15750919ab4a6846cac62a56c2aa43e8329a Mon Sep 17 00:00:00 2001
From: Denis Gantsev <gantsevdenis@gmail.com>
Date: Mon, 4 Nov 2019 02:01:01 +0100
Subject: [PATCH 3/7] typo
---
mypy/checker.py | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mypy/checker.py b/mypy/checker.py
index d8640799e8f4..ffb76b6fc424 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -3721,7 +3721,7 @@ def find_isinstance_check(self, node: Expression
for name, expr_ in self.ctns:
if refers_to_fullname(node.callee, name):
expr = node.args[0]
- if literal(expr_) == LITERAL_TYPE:
+ if literal(expr) == LITERAL_TYPE:
vartype = type_map[node.args[0]]
type = get_isinstance_type(expr_, type_map)
break # name is unique
From 28e3ea7488272423182b2a0e1275a7811d94cbe3 Mon Sep 17 00:00:00 2001
From: Denis Gantsev <gantsevdenis@gmail.com>
Date: Mon, 4 Nov 2019 20:43:22 +0100
Subject: [PATCH 4/7] add tests
---
test-data/unit/check-isinstance.test | 49 ++++++++++++++++++++++++++++
1 file changed, 49 insertions(+)
diff --git a/test-data/unit/check-isinstance.test b/test-data/unit/check-isinstance.test
index 2b62699b5166..ac7161dca94a 100644
--- a/test-data/unit/check-isinstance.test
+++ b/test-data/unit/check-isinstance.test
@@ -2279,3 +2279,52 @@ var = 'some string'
if isinstance(var, *(str, int)): # E: Too many arguments for "isinstance"
pass
[builtins fixtures/isinstancelist.pyi]
+
+[case testCustomTypeNarrower]
+from typing import Union, List, Tuple, Any, Callable
+from mypy.extern import narrow_cast
+@narrow_cast(int)
+def isint(x: Union[str, int], *args) -> bool:
+ return isinstance(x, int)
+
+@narrow_cast(str)
+def isstr(x, name) -> bool:
+ return name == 'STRING'
+
+u: Union[str, int] = 5
+x: Union[str, float]
+if isint(u):
+ reveal_type(u) # N: Revealed type is 'builtins.int'
+if isinstance(u, int):
+ reveal_type(u) # N: Revealed type is 'builtins.int'
+if isstr(x, 'STRING'):
+ x + ""
+
+@narrow_cast(str)
+def is_fizz_buzz(foo):
+ return foo in ['fizz', 'buzz']
+
+def foobar(foo: Union[str, float]):
+ if foo in ['fizz', 'buzz']:
+ reveal_type(foo) # N: Revealed type is 'Union[builtins.str, builtins.float]'
+ if is_fizz_buzz(foo):
+ reveal_type(foo) # N: Revealed type is 'builtins.str'
+
+@narrow_cast((str, (int,)))
+def is_str_or_int(x):
+ return isinstance(x, (str, (int,)))
+
+@narrow_cast((str, (list,)))
+def is_str_or_list(x):
+ return isinstance(x, (str, (list,)))
+
+def f(x: Union[int, str, List]) -> None:
+ if isinstance(x, (str, (int,))):
+ reveal_type(x) # N: Revealed type is 'Union[builtins.int, builtins.str]'
+ if is_str_or_int(x):
+ reveal_type(x) # N: Revealed type is 'Union[builtins.int, builtins.str]'
+ if isinstance(x, (str, (list,))):
+ reveal_type(x) # N: Revealed type is 'Union[builtins.str, builtins.list[Any]]'
+ if is_str_or_list(x):
+ reveal_type(x) # N: Revealed type is 'Union[builtins.str, builtins.list[Any]]'
+[builtins fixtures/isinstancelist.pyi]
From 6ca754216a1a38db208e1a48d6a42c9f40e7ac0c Mon Sep 17 00:00:00 2001
From: Denis Gantsev <gantsevdenis@gmail.com>
Date: Mon, 4 Nov 2019 20:44:51 +0100
Subject: [PATCH 5/7] import && stub
---
mypy/checkexpr.py | 7 ++++---
test-data/unit/lib-stub/mypy/__init__.py | 0
test-data/unit/lib-stub/mypy/extern.py | 10 ++++++++++
3 files changed, 14 insertions(+), 3 deletions(-)
create mode 100644 test-data/unit/lib-stub/mypy/__init__.py
create mode 100644 test-data/unit/lib-stub/mypy/extern.py
diff --git a/mypy/checkexpr.py b/mypy/checkexpr.py
index f8abfcc1e515..096e147a3fb6 100644
--- a/mypy/checkexpr.py
+++ b/mypy/checkexpr.py
@@ -61,6 +61,7 @@
tuple_fallback, make_simplified_union, true_only, false_only, erase_to_union_or_bound,
function_type, callable_type, try_getting_str_literals
)
+from mypy.semanal import refers_to_fullname
import mypy.errorcodes as codes
# Type of callback user for checking individual function arguments. See
@@ -272,8 +273,8 @@ def visit_call_expr_inner(self, e: CallExpr, allow_none_return: bool = False) ->
return self.check_typeddict_call(typeddict_type, e.arg_kinds, e.arg_names, e.args, e)
if (isinstance(e.callee, NameExpr)
and ((e.callee.name in ('isinstance', 'issubclass') and len(e.args) == 2)
- or e.callee.name == 'narrow_cast' and len(e.args) == 1)):
- is_narrow_cast = e.callee.name == 'narrow_cast'
+ or refers_to_fullname(e.callee, 'mypy.extern.narrow_cast') and len(e.args) == 1)):
+ is_narrow_cast = refers_to_fullname(e.callee, 'mypy.extern.narrow_cast')
arg = e.args[1] if not is_narrow_cast else e.args[0]
for typ in mypy.checker.flatten(arg):
node = None
@@ -3316,7 +3317,7 @@ def visit_super_expr(self, e: SuperExpr) -> Type:
self.chk.fail(message_registry.SUPER_ARG_2_NOT_INSTANCE_OF_ARG_1, e)
return AnyType(TypeOfAny.from_error)
- for base in mro[index+1:]:
+ for base in mro[index + 1:]:
if e.name in base.names or base == mro[-1]:
if e.info and e.info.fallback_to_any and base == mro[-1]:
# There's an undefined base class, and we're at the end of the
diff --git a/test-data/unit/lib-stub/mypy/__init__.py b/test-data/unit/lib-stub/mypy/__init__.py
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/test-data/unit/lib-stub/mypy/extern.py b/test-data/unit/lib-stub/mypy/extern.py
new file mode 100644
index 000000000000..973c42a9fd23
--- /dev/null
+++ b/test-data/unit/lib-stub/mypy/extern.py
@@ -0,0 +1,10 @@
+from typing import Union, Tuple, Any, Callable
+
+
+# copy pasted from typeshed
+def narrow_cast(T: Union[type, Tuple[Union[type, Tuple[Any, ...]], ...]]) \
+ -> Callable[..., Callable[..., bool]]:
+ def narrow_cast_inner(f: Callable[..., bool]) -> Callable[..., bool]:
+ return f # binds first argument of f to T
+
+ return narrow_cast_inner
From ee48fb436c60702e802294e6ab03d68e1137e71d Mon Sep 17 00:00:00 2001
From: Denis Gantsev <gantsevdenis@gmail.com>
Date: Mon, 4 Nov 2019 20:48:32 +0100
Subject: [PATCH 6/7] comment
---
mypy/extern.py | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mypy/extern.py b/mypy/extern.py
index 973c42a9fd23..d796dd15a1d6 100644
--- a/mypy/extern.py
+++ b/mypy/extern.py
@@ -1,7 +1,7 @@
from typing import Union, Tuple, Any, Callable
-# copy pasted from typeshed
+# signature is partially copy pasted from typeshed isinstance
def narrow_cast(T: Union[type, Tuple[Union[type, Tuple[Any, ...]], ...]]) \
-> Callable[..., Callable[..., bool]]:
def narrow_cast_inner(f: Callable[..., bool]) -> Callable[..., bool]:
From e4574eee1a44643d7917f4c3f48705b5759a252d Mon Sep 17 00:00:00 2001
From: Denis Gantsev <gantsevdenis@gmail.com>
Date: Mon, 4 Nov 2019 21:31:38 +0100
Subject: [PATCH 7/7] flake8
---
mypy/checker.py | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mypy/checker.py b/mypy/checker.py
index ffb76b6fc424..63ae070a6eb0 100644
--- a/mypy/checker.py
+++ b/mypy/checker.py
@@ -165,9 +165,9 @@ class TypeChecker(NodeVisitor[None], CheckerPluginInterface):
# temporary container for ctn
ctns_queue = None # type:List[str]
# uniqueness check for ctn
- ctns_keys = None # type:Set[str]
+ ctns_keys = None # type: Set[str]
# custom type narrowers
- ctns = None # type:List[Tuple[str, Expression]]
+ ctns = None # type: List[Tuple[str, Expression]]
tscope = None # type: Scope
scope = None # type: CheckerScope
# Stack of function return types