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Improve error message for partial None with --local-partial-types #12822

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merged 5 commits into from
Sep 2, 2022
Merged

Improve error message for partial None with --local-partial-types #12822

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3d1323e
Improve error message for partial Nones
pranavrajpal May 20, 2022
6c91b91
Fix fine grained tests
pranavrajpal May 20, 2022
c469567
Suggest PEP 604 annotation when on Python 3.10
pranavrajpal May 20, 2022
3a96b8b
Merge remote-tracking branch 'upstream/master' into improve-partial-N…
hauntsaninja Sep 2, 2022
0dff510
blacken, fix nit
hauntsaninja Sep 2, 2022
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33 changes: 20 additions & 13 deletions mypy/messages.py
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Original file line number Diff line number Diff line change
Expand Up @@ -1526,23 +1526,30 @@ def need_annotation_for_var(
) -> None:
hint = ""
has_variable_annotations = not python_version or python_version >= (3, 6)
pep604_supported = not python_version or python_version >= (3, 10)
# type to recommend the user adds
recommended_type = None
# Only gives hint if it's a variable declaration and the partial type is a builtin type
if (
python_version
and isinstance(node, Var)
and isinstance(node.type, PartialType)
and node.type.type
and node.type.type.fullname in reverse_builtin_aliases
):
alias = reverse_builtin_aliases[node.type.type.fullname]
alias = alias.split(".")[-1]
if python_version and isinstance(node, Var) and isinstance(node.type, PartialType):
type_dec = "<type>"
if alias == "Dict":
type_dec = f"{type_dec}, {type_dec}"
if not node.type.type:
# partial None
if pep604_supported:
recommended_type = f"{type_dec} | None"
else:
recommended_type = f"Optional[{type_dec}]"
elif node.type.type.fullname in reverse_builtin_aliases:
# partial types other than partial None
alias = reverse_builtin_aliases[node.type.type.fullname]
alias = alias.split(".")[-1]
if alias == "Dict":
type_dec = f"{type_dec}, {type_dec}"
recommended_type = f"{alias}[{type_dec}]"
if recommended_type is not None:
if has_variable_annotations:
hint = f' (hint: "{node.name}: {alias}[{type_dec}] = ...")'
hint = f' (hint: "{node.name}: {recommended_type} = ...")'
else:
hint = f' (hint: "{node.name} = ... # type: {alias}[{type_dec}]")'
hint = f' (hint: "{node.name} = ... # type: {recommended_type}")'

if has_variable_annotations:
needed = "annotation"
Expand Down
16 changes: 10 additions & 6 deletions test-data/unit/check-inference.test
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Expand Up @@ -2393,7 +2393,7 @@ if bool():

[case testLocalPartialTypesWithGlobalInitializedToNone]
# flags: --local-partial-types
x = None # E: Need type annotation for "x"
x = None # E: Need type annotation for "x" (hint: "x: Optional[<type>] = ...")
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def f() -> None:
global x
Expand All @@ -2404,7 +2404,7 @@ reveal_type(x) # N: Revealed type is "None"

[case testLocalPartialTypesWithGlobalInitializedToNone2]
# flags: --local-partial-types
x = None # E: Need type annotation for "x"
x = None # E: Need type annotation for "x" (hint: "x: Optional[<type>] = ...")

def f():
global x
Expand Down Expand Up @@ -2453,7 +2453,7 @@ reveal_type(a) # N: Revealed type is "builtins.str"
[case testLocalPartialTypesWithClassAttributeInitializedToNone]
# flags: --local-partial-types
class A:
x = None # E: Need type annotation for "x"
x = None # E: Need type annotation for "x" (hint: "x: Optional[<type>] = ...")

def f(self) -> None:
self.x = 1
Expand Down Expand Up @@ -2636,7 +2636,7 @@ from typing import List
def f(x): pass

class A:
x = None # E: Need type annotation for "x"
x = None # E: Need type annotation for "x" (hint: "x: Optional[<type>] = ...")

def f(self, p: List[str]) -> None:
self.x = f(p)
Expand All @@ -2646,15 +2646,15 @@ class A:
[case testLocalPartialTypesAccessPartialNoneAttribute]
# flags: --local-partial-types
class C:
a = None # E: Need type annotation for "a"
a = None # E: Need type annotation for "a" (hint: "a: Optional[<type>] = ...")

def f(self, x) -> None:
C.a.y # E: Item "None" of "Optional[Any]" has no attribute "y"

[case testLocalPartialTypesAccessPartialNoneAttribute2]
# flags: --local-partial-types
class C:
a = None # E: Need type annotation for "a"
a = None # E: Need type annotation for "a" (hint: "a: Optional[<type>] = ...")

def f(self, x) -> None:
self.a.y # E: Item "None" of "Optional[Any]" has no attribute "y"
Expand Down Expand Up @@ -3248,6 +3248,10 @@ if x:
reveal_type(x) # N: Revealed type is "builtins.bytes"
[builtins fixtures/dict.pyi]

[case testSuggestPep604AnnotationForPartialNone]
# flags: --local-partial-types --python-version 3.10
x = None # E: Need type annotation for "x" (hint: "x: <type> | None = ...")

[case testTupleContextFromIterable]
from typing import TypeVar, Iterable, List, Union

Expand Down
12 changes: 6 additions & 6 deletions test-data/unit/fine-grained.test
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Expand Up @@ -4305,9 +4305,9 @@ y = 0
[file a.py.2]
y = ''
[out]
main:4: error: Need type annotation for "x"
main:4: error: Need type annotation for "x" (hint: "x: Optional[<type>] = ...")
==
main:4: error: Need type annotation for "x"
main:4: error: Need type annotation for "x" (hint: "x: Optional[<type>] = ...")

[case testNonePartialType2]
import a
Expand All @@ -4323,9 +4323,9 @@ y = 0
[file a.py.2]
y = ''
[out]
main:4: error: Need type annotation for "x"
main:4: error: Need type annotation for "x" (hint: "x: Optional[<type>] = ...")
==
main:4: error: Need type annotation for "x"
main:4: error: Need type annotation for "x" (hint: "x: Optional[<type>] = ...")

[case testNonePartialType3]
import a
Expand All @@ -4337,7 +4337,7 @@ def f() -> None:
y = ''
[out]
==
a.py:1: error: Need type annotation for "y"
a.py:1: error: Need type annotation for "y" (hint: "y: Optional[<type>] = ...")

[case testNonePartialType4]
import a
Expand All @@ -4353,7 +4353,7 @@ def f() -> None:
global y
y = ''
[out]
a.py:1: error: Need type annotation for "y"
a.py:1: error: Need type annotation for "y" (hint: "y: Optional[<type>] = ...")
==

[case testSkippedClass1]
Expand Down