Remove "builtins." from output for overloads and builtins.None (#5073)

Part of #5072.

Overloads are probably the most common user-facing feature that still outputs "builtins" in error messages; this diff fixes them to use standard type formatting.

I also change builtins.None to None, since builtins.None is a syntax error. A comment claimed that we use builtins.None to distinguish the type from the value, but I don't think there are a lot of contexts where that confusion is likely.

Author: JelleZijlstra

mypy/messages.py

@@ -748,10 +748,20 @@ def no_variant_matches_arguments(self, overload: Overloaded, arg_types: List[Typ
                                      context: Context) -> None:
         name = callable_name(overload)
         if name:
-            self.fail('No overload variant of {} matches argument types {}'
-                      .format(name, arg_types), context)
+            name_str = ' of {}'.format(name)
         else:
-            self.fail('No overload variant matches argument types {}'.format(arg_types), context)
+            name_str = ''
+        arg_types_str = ', '.join(self.format(arg) for arg in arg_types)
+        num_args = len(arg_types)
+        if num_args == 0:
+            self.fail('All overload variants{} require at least one argument'.format(name_str),
+                      context)
+        elif num_args == 1:
+            self.fail('No overload variant{} matches argument type {}'
+                      .format(name_str, arg_types_str), context)
+        else:
+            self.fail('No overload variant{} matches argument types {}'
+                      .format(name_str, arg_types_str), context)
 
     def wrong_number_values_to_unpack(self, provided: int, expected: int,
                                       context: Context) -> None:

mypy/types.py

@@ -1680,8 +1680,7 @@ def visit_any(self, t: AnyType) -> str:
         return 'Any'
 
     def visit_none_type(self, t: NoneTyp) -> str:
-        # Fully qualify to make this distinct from the None value.
-        return "builtins.None"
+        return "None"
 
     def visit_uninhabited_type(self, t: UninhabitedType) -> str:
         return "<nothing>"

test-data/unit/check-abstract.test

@@ -525,7 +525,7 @@ B().f(1)
 a = B() # type: A
 a.f(1)
 a.f('')
-a.f(B()) # E: No overload variant of "f" of "A" matches argument types [foo.B]
+a.f(B()) # E: No overload variant of "f" of "A" matches argument type "B"
 
 [case testOverloadedAbstractMethodWithAlternativeDecoratorOrder]
 from foo import *
@@ -552,7 +552,7 @@ B().f(1)
 a = B() # type: A
 a.f(1)
 a.f('')
-a.f(B()) # E: No overload variant of "f" of "A" matches argument types [foo.B]
+a.f(B()) # E: No overload variant of "f" of "A" matches argument type "B"
 
 [case testOverloadedAbstractMethodVariantMissingDecorator1]
 from foo import *

test-data/unit/check-async-await.test

@@ -441,8 +441,8 @@ async def g() -> AsyncGenerator[int, None]:
     yield 'not an int'  # E: Incompatible types in "yield" (actual type "str", expected type "int")
     # return without a value is fine
     return
-reveal_type(g)  # E: Revealed type is 'def () -> typing.AsyncGenerator[builtins.int, builtins.None]'
-reveal_type(g())  # E: Revealed type is 'typing.AsyncGenerator[builtins.int, builtins.None]'
+reveal_type(g)  # E: Revealed type is 'def () -> typing.AsyncGenerator[builtins.int, None]'
+reveal_type(g())  # E: Revealed type is 'typing.AsyncGenerator[builtins.int, None]'
 
 async def h() -> None:
     async for item in g():
@@ -481,7 +481,7 @@ async def genfunc() -> AsyncGenerator[int, None]:
 async def user() -> None:
     gen = genfunc()
 
-    reveal_type(gen.__aiter__())  # E: Revealed type is 'typing.AsyncGenerator[builtins.int*, builtins.None]'
+    reveal_type(gen.__aiter__())  # E: Revealed type is 'typing.AsyncGenerator[builtins.int*, None]'
 
     reveal_type(await gen.__anext__())  # E: Revealed type is 'builtins.int*'
 

test-data/unit/check-class-namedtuple.test

@@ -408,7 +408,7 @@ class HasNone(NamedTuple):
     x: int
     y: Optional[int] = None
 
-reveal_type(HasNone(1))  # E: Revealed type is 'Tuple[builtins.int, Union[builtins.int, builtins.None], fallback=__main__.HasNone]'
+reveal_type(HasNone(1))  # E: Revealed type is 'Tuple[builtins.int, Union[builtins.int, None], fallback=__main__.HasNone]'
 
 class Parameterized(NamedTuple):
     x: int
@@ -438,7 +438,7 @@ class HasNone(NamedTuple):
     x: int
     y: Optional[int] = None
 
-reveal_type(HasNone(1))  # E: Revealed type is 'Tuple[builtins.int, Union[builtins.int, builtins.None], fallback=__main__.HasNone]'
+reveal_type(HasNone(1))  # E: Revealed type is 'Tuple[builtins.int, Union[builtins.int, None], fallback=__main__.HasNone]'
 HasNone(None)  # E: Argument 1 to "HasNone" has incompatible type "None"; expected "int"
 HasNone(1, y=None)
 HasNone(1, y=2)
@@ -523,7 +523,7 @@ class Overloader(NamedTuple):
 
 reveal_type(Overloader(1).method('string'))  # E: Revealed type is 'builtins.str'
 reveal_type(Overloader(1).method(1))  # E: Revealed type is 'builtins.int'
-Overloader(1).method(('tuple',))  # E: No overload variant of "method" of "Overloader" matches argument types [Tuple[builtins.str]]
+Overloader(1).method(('tuple',))  # E: No overload variant of "method" of "Overloader" matches argument type "Tuple[str]"
 
 [case testNewNamedTupleMethodInheritance]
 from typing import NamedTuple, TypeVar

test-data/unit/check-classes.test

@@ -1224,9 +1224,9 @@ class D:
 [builtins fixtures/bool.pyi]
 [out]
 main:5: error: Revealed type is 'Any'
-main:5: error: No overload variant of "__get__" of "D" matches argument types [builtins.None, Type[__main__.A]]
+main:5: error: No overload variant of "__get__" of "D" matches argument types "None", "Type[A]"
 main:6: error: Revealed type is 'Any'
-main:6: error: No overload variant of "__get__" of "D" matches argument types [__main__.A, Type[__main__.A]]
+main:6: error: No overload variant of "__get__" of "D" matches argument types "A", "Type[A]"
 
 
 [case testAccessingGenericNonDataDescriptor]
@@ -1324,7 +1324,7 @@ class D(Generic[T, V]):
 [builtins fixtures/bool.pyi]
 [out]
 main:5: error: Revealed type is 'Any'
-main:5: error: No overload variant of "__get__" of "D" matches argument types [builtins.None, Type[__main__.A]]
+main:5: error: No overload variant of "__get__" of "D" matches argument types "None", "Type[A]"
 
 [case testAccessingNonDataDescriptorSubclass]
 from typing import Any
@@ -2094,7 +2094,7 @@ class C:
 c = C(1)
 c.a # E: "C" has no attribute "a"
 C('', '')
-C('') # E: No overload variant of "C" matches argument types [builtins.str]
+C('') # E: No overload variant of "C" matches argument type "str"
 [builtins fixtures/__new__.pyi]
 
 
@@ -2516,7 +2516,7 @@ def new(uc: Type[U]) -> U:
 u = new(User)
 [builtins fixtures/classmethod.pyi]
 [out]
-tmp/foo.pyi:16: error: No overload variant of "User" matches argument types [builtins.str]
+tmp/foo.pyi:16: error: No overload variant of "User" matches argument type "str"
 tmp/foo.pyi:17: error: Too many arguments for "foo" of "User"
 
 [case testTypeUsingTypeCInUpperBound]
@@ -2712,7 +2712,7 @@ def f(a: int) -> None: pass
 def mock() -> type: return User
 
 f(User)
-f(mock())  # E: No overload variant of "f" matches argument types [builtins.type]
+f(mock())  # E: No overload variant of "f" matches argument type "type"
 [builtins fixtures/classmethod.pyi]
 [out]
 
@@ -2728,7 +2728,7 @@ def f(a: Type[User]) -> None: pass
 @overload
 def f(a: type) -> None: pass
 
-f(3)  # E: No overload variant of "f" matches argument types [builtins.int]
+f(3)  # E: No overload variant of "f" matches argument type "int"
 [builtins fixtures/classmethod.pyi]
 [out]
 
@@ -2745,7 +2745,7 @@ def f(a: Type[User]) -> None: pass
 def f(a: int) -> None: pass
 
 f(User)
-f(User())  # E: No overload variant of "f" matches argument types [foo.User]
+f(User())  # E: No overload variant of "f" matches argument type "User"
 [builtins fixtures/classmethod.pyi]
 [out]
 
@@ -2766,10 +2766,10 @@ def f(a: Type[B]) -> None: pass
 @overload
 def f(a: int) -> None: pass
 
-f(A)  # E: No overload variant of "f" matches argument types [def () -> foo.A]
+f(A)  # E: No overload variant of "f" matches argument type "Type[A]"
 f(B)
 f(C)
-f(AType)  # E: No overload variant of "f" matches argument types [Type[foo.A]]
+f(AType)  # E: No overload variant of "f" matches argument type "Type[A]"
 f(BType)
 f(CType)
 [builtins fixtures/classmethod.pyi]

test-data/unit/check-expressions.test

@@ -866,7 +866,7 @@ from typing import overload
 a, b, c = None, None, None  # type: (A, B, C)
 a[b]
 a[c]
-a[1]  # E: No overload variant of "__getitem__" of "A" matches argument types [builtins.int]
+a[1]  # E: No overload variant of "__getitem__" of "A" matches argument type "int"
 
 i, s = None, None  # type: (int, str)
 i = a[b]

test-data/unit/check-fastparse.test

@@ -130,9 +130,9 @@ def f(a,        # type: A
       **kwargs  # type: F
       ):
     reveal_type(a)      # E: Revealed type is '__main__.A'
-    reveal_type(b)      # E: Revealed type is 'Union[__main__.B, builtins.None]'
+    reveal_type(b)      # E: Revealed type is 'Union[__main__.B, None]'
     reveal_type(args)   # E: Revealed type is 'builtins.tuple[__main__.C]'
-    reveal_type(d)      # E: Revealed type is 'Union[__main__.D, builtins.None]'
+    reveal_type(d)      # E: Revealed type is 'Union[__main__.D, None]'
     reveal_type(e)      # E: Revealed type is '__main__.E'
     reveal_type(kwargs) # E: Revealed type is 'builtins.dict[builtins.str, __main__.F]'
 [builtins fixtures/dict.pyi]
@@ -155,9 +155,9 @@ def f(a,        # type: A
       ):
       # type: (...) -> int
     reveal_type(a)      # E: Revealed type is '__main__.A'
-    reveal_type(b)      # E: Revealed type is 'Union[__main__.B, builtins.None]'
+    reveal_type(b)      # E: Revealed type is 'Union[__main__.B, None]'
     reveal_type(args)   # E: Revealed type is 'builtins.tuple[__main__.C]'
-    reveal_type(d)      # E: Revealed type is 'Union[__main__.D, builtins.None]'
+    reveal_type(d)      # E: Revealed type is 'Union[__main__.D, None]'
     reveal_type(e)      # E: Revealed type is '__main__.E'
     reveal_type(kwargs) # E: Revealed type is 'builtins.dict[builtins.str, __main__.F]'
     return "not an int"  # E: Incompatible return value type (got "str", expected "int")
@@ -197,7 +197,7 @@ def f(a,        # type: A
       # kwargs not tested due to lack of 2.7 dict fixtures
       ):
     reveal_type(a)      # E: Revealed type is '__main__.A'
-    reveal_type(b)      # E: Revealed type is 'Union[__main__.B, builtins.None]'
+    reveal_type(b)      # E: Revealed type is 'Union[__main__.B, None]'
     reveal_type(args)   # E: Revealed type is 'builtins.tuple[__main__.C]'
 [builtins fixtures/dict.pyi]
 [out]
@@ -215,7 +215,7 @@ def f(a,        # type: A
       ):
       # type: (...) -> int
     reveal_type(a)      # E: Revealed type is '__main__.A'
-    reveal_type(b)      # E: Revealed type is 'Union[__main__.B, builtins.None]'
+    reveal_type(b)      # E: Revealed type is 'Union[__main__.B, None]'
     reveal_type(args)   # E: Revealed type is 'builtins.tuple[__main__.C]'
     return "not an int"  # E: Incompatible return value type (got "str", expected "int")
 [builtins fixtures/dict.pyi]

test-data/unit/check-functions.test

@@ -534,7 +534,7 @@ class A:
 a = None # type: A
 a.g()
 a.g(B())
-a.g(a) # E: No overload variant matches argument types [foo.A]
+a.g(a) # E: No overload variant matches argument type "A"
 
 [case testMethodAsDataAttributeInferredFromDynamicallyTypedMethod]
 

test-data/unit/check-generics.test

@@ -960,7 +960,7 @@ U = Union[int]
 x: O
 y: U
 
-reveal_type(x)  # E: Revealed type is 'Union[builtins.int, builtins.None]'
+reveal_type(x)  # E: Revealed type is 'Union[builtins.int, None]'
 reveal_type(y)  # E: Revealed type is 'builtins.int'
 
 U[int]  # E: Bad number of arguments for type alias, expected: 0, given: 1

test-data/unit/check-incremental.test

@@ -3798,9 +3798,9 @@ class A:
 
 [builtins fixtures/list.pyi]
 [out1]
-main:2: error: Revealed type is 'def (x: Union[builtins.int, builtins.None]) -> a.a.A'
+main:2: error: Revealed type is 'def (x: Union[builtins.int, None]) -> a.a.A'
 [out2]
-main:2: error: Revealed type is 'def (x: Union[builtins.int, builtins.None]) -> a.a.A'
+main:2: error: Revealed type is 'def (x: Union[builtins.int, None]) -> a.a.A'
 
 [case testAttrsIncrementalConverterManyStyles]
 import a

test-data/unit/check-inference-context.test

@@ -867,7 +867,7 @@ T = TypeVar('T')
 def f(x: Union[T, List[int]]) -> Union[T, List[int]]: pass
 reveal_type(f(1)) # E: Revealed type is 'Union[builtins.int*, builtins.list[builtins.int]]'
 reveal_type(f([])) # E: Revealed type is 'builtins.list[builtins.int]'
-reveal_type(f(None)) # E: Revealed type is 'Union[builtins.None, builtins.list[builtins.int]]'
+reveal_type(f(None)) # E: Revealed type is 'Union[None, builtins.list[builtins.int]]'
 [builtins fixtures/list.pyi]
 
 [case testUnionWithGenericTypeItemContextInMethod]

test-data/unit/check-inference.test

@@ -1470,7 +1470,7 @@ def f(blocks: Any): # E: Name 'Any' is not defined
 [case testSpecialCaseEmptyListInitialization2]
 def f(blocks: object):
     to_process = [] # E: Need type annotation for 'to_process'
-    to_process = list(blocks) # E: No overload variant of "list" matches argument types [builtins.object]
+    to_process = list(blocks) # E: No overload variant of "list" matches argument type "object"
 [builtins fixtures/list.pyi]
 [out]
 
@@ -1551,7 +1551,7 @@ if object():
 [case testPartiallyInitializedVariableDoesNotEscapeScope1]
 def f() -> None:
     x = None
-    reveal_type(x)  # E: Revealed type is 'builtins.None'
+    reveal_type(x)  # E: Revealed type is 'None'
 x = 1
 [out]
 
@@ -2088,7 +2088,7 @@ def f() -> None:
     x = 1
 
 # TODO: "Any" could be a better type here to avoid multiple error messages
-reveal_type(x) # E: Revealed type is 'builtins.None'
+reveal_type(x) # E: Revealed type is 'None'
 
 [case testLocalPartialTypesWithGlobalInitializedToNone2]
 # flags: --local-partial-types
@@ -2099,7 +2099,7 @@ def f():
     x = 1
 
 # TODO: "Any" could be a better type here to avoid multiple error messages
-reveal_type(x) # E: Revealed type is 'builtins.None'
+reveal_type(x) # E: Revealed type is 'None'
 
 [case testLocalPartialTypesWithGlobalInitializedToNone3]
 # flags: --local-partial-types --no-strict-optional
@@ -2122,7 +2122,7 @@ def f() -> None:
 
 x = ''
 def g() -> None:
-    reveal_type(x) # E: Revealed type is 'Union[builtins.str, builtins.None]'
+    reveal_type(x) # E: Revealed type is 'Union[builtins.str, None]'
 
 [case testLocalPartialTypesWithGlobalInitializedToNone4]
 # flags: --local-partial-types --no-strict-optional
@@ -2133,7 +2133,7 @@ def f() -> None:
 
 # TODO: This should probably be 'builtins.str', since there could be a
 #     call that causes a non-None value to be assigned
-reveal_type(a)  # E: Revealed type is 'builtins.None'
+reveal_type(a)  # E: Revealed type is 'None'
 a = ''
 reveal_type(a)  # E: Revealed type is 'builtins.str'
 [builtins fixtures/list.pyi]
@@ -2262,7 +2262,7 @@ class A:
 class B(A):
     x = None
 
-reveal_type(B.x) # E: Revealed type is 'builtins.None'
+reveal_type(B.x) # E: Revealed type is 'None'
 
 [case testLocalPartialTypesWithInheritance2]
 # flags: --local-partial-types --strict-optional
@@ -2298,8 +2298,8 @@ class C(B):
     x = None
 
 # TODO: Inferring None below is unsafe (https://github.com/python/mypy/issues/3208)
-reveal_type(B.x)  # E: Revealed type is 'builtins.None'
-reveal_type(C.x)  # E: Revealed type is 'builtins.None'
+reveal_type(B.x)  # E: Revealed type is 'None'
+reveal_type(C.x)  # E: Revealed type is 'None'
 
 [case testLocalPartialTypesWithInheritance2-skip]
 # flags: --local-partial-types
@@ -2316,7 +2316,7 @@ class B(A):
     x = None
     x = Y()
 
-reveal_type(B.x) # E: revealed type is 'Union[__main__.Y, builtins.None]'
+reveal_type(B.x) # E: revealed type is 'Union[__main__.Y, None]'
 
 [case testLocalPartialTypesBinderSpecialCase]
 # flags: --local-partial-types