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hauntsaninja merged 3 commits into from
Sep 2, 2023
Merged

Reword the error message related to void functions #15876

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846701d
Reword the error message related to void functions
atugushev Aug 15, 2023
dceaac1
Address review comment
atugushev Aug 15, 2023
25e0322
wording suggestion
hauntsaninja Sep 2, 2023
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2 changes: 1 addition & 1 deletion docs/source/error_code_list.rst
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Expand Up @@ -741,7 +741,7 @@ returns ``None``:
# OK: we don't do anything with the return value
f()

# Error: "f" does not return a value [func-returns-value]
# Error: "f" does not return a value (or returns None) [func-returns-value]
if f():
print("not false")

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12 changes: 4 additions & 8 deletions mypy/messages.py
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Expand Up @@ -1025,14 +1025,10 @@ def does_not_return_value(self, callee_type: Type | None, context: Context) -> N
callee_type = get_proper_type(callee_type)
if isinstance(callee_type, FunctionLike):
name = callable_name(callee_type)
if name is not None:
self.fail(
f"{capitalize(name)} does not return a value",
context,
code=codes.FUNC_RETURNS_VALUE,
)
else:
self.fail("Function does not return a value", context, code=codes.FUNC_RETURNS_VALUE)
message = "{} does not return a value (or returns None)".format(
"Function" if name is None else capitalize(name)
)
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@ikonst ikonst Aug 15, 2023 •
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Suggested change
message = "{} does not return a value (or returns None)".format(
"Function" if name is None else capitalize(name)
)
name = capitalize(name or "Function")
message = f"{name} does not return a value (or returns None)"

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@atugushev atugushev Aug 15, 2023 •
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Suggested change
message = "{} does not return a value (or returns None)".format(
"Function" if name is None else capitalize(name)
)
name = "Function" if name is None else capitalize(name)
message = f"{name} does not return a value (or returns None)"

Thanks for the suggestion! By using an f-string along with the name variable the code definitely looks better. One note, perhaps we could keep an explicit check for None as in the original code?

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@ikonst ikonst Aug 15, 2023

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Of course. :)

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@ikonst ikonst Aug 15, 2023

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(I "simplified" it because an empty string wouldn't make for a good interpolation either, but it also suggests it's a possibility where currently it's not.)

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@atugushev atugushev Aug 15, 2023

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Considering the implementation of callable_name() it seems to me that we could omit the capitalization:

mypy/mypy/messages.py

Lines 2963 to 2967 in b49be10

def callable_name(type: FunctionLike) -> str | None:
name = type.get_name()
if name is not None and name[0] != "<":
return f'"{name}"'.replace(" of ", '" of "')
return name

It always returns either None, "Foo", or <Foo>, where capitalization does not seem to be applicable. What do you think?

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@atugushev atugushev Aug 15, 2023

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Addressed in dceaac1

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Looks much better!

self.fail(message, context, code=codes.FUNC_RETURNS_VALUE)

def deleted_as_rvalue(self, typ: DeletedType, context: Context) -> None:
"""Report an error about using an deleted type as an rvalue."""
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6 changes: 3 additions & 3 deletions test-data/unit/check-errorcodes.test
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Original file line number Diff line number Diff line change
Expand Up @@ -553,15 +553,15 @@ from typing import Callable

def f() -> None: pass

x = f() # E: "f" does not return a value [func-returns-value]
x = f() # E: "f" does not return a value (or returns None) [func-returns-value]

class A:
def g(self) -> None: pass

y = A().g() # E: "g" of "A" does not return a value [func-returns-value]
y = A().g() # E: "g" of "A" does not return a value (or returns None) [func-returns-value]

c: Callable[[], None]
z = c() # E: Function does not return a value [func-returns-value]
z = c() # E: Function does not return a value (or returns None) [func-returns-value]

[case testErrorCodeInstantiateAbstract]
from abc import abstractmethod
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66 changes: 33 additions & 33 deletions test-data/unit/check-expressions.test
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Expand Up @@ -1062,15 +1062,15 @@ class A:
a: A
o: object
if int():
a = f() # E: "f" does not return a value
a = f() # E: "f" does not return a value (or returns None)
if int():
o = a() # E: Function does not return a value
o = a() # E: Function does not return a value (or returns None)
if int():
o = A().g(a) # E: "g" of "A" does not return a value
o = A().g(a) # E: "g" of "A" does not return a value (or returns None)
if int():
o = A.g(a, a) # E: "g" of "A" does not return a value
A().g(f()) # E: "f" does not return a value
x: A = f() # E: "f" does not return a value
o = A.g(a, a) # E: "g" of "A" does not return a value (or returns None)
A().g(f()) # E: "f" does not return a value (or returns None)
x: A = f() # E: "f" does not return a value (or returns None)
f()
A().g(a)
[builtins fixtures/tuple.pyi]
Expand All @@ -1079,15 +1079,15 @@ A().g(a)
import typing
def f() -> None: pass

if f(): # E: "f" does not return a value
if f(): # E: "f" does not return a value (or returns None)
pass
elif f(): # E: "f" does not return a value
elif f(): # E: "f" does not return a value (or returns None)
pass
while f(): # E: "f" does not return a value
while f(): # E: "f" does not return a value (or returns None)
pass
def g() -> object:
return f() # E: "f" does not return a value
raise f() # E: "f" does not return a value
return f() # E: "f" does not return a value (or returns None)
raise f() # E: "f" does not return a value (or returns None)
[builtins fixtures/exception.pyi]

[case testNoneReturnTypeWithExpressions]
Expand All @@ -1098,13 +1098,13 @@ class A:
def __add__(self, x: 'A') -> 'A': pass

a: A
[f()] # E: "f" does not return a value
f() + a # E: "f" does not return a value
a + f() # E: "f" does not return a value
f() == a # E: "f" does not return a value
a != f() # E: "f" does not return a value
[f()] # E: "f" does not return a value (or returns None)
f() + a # E: "f" does not return a value (or returns None)
a + f() # E: "f" does not return a value (or returns None)
f() == a # E: "f" does not return a value (or returns None)
a != f() # E: "f" does not return a value (or returns None)
cast(A, f())
f().foo # E: "f" does not return a value
f().foo # E: "f" does not return a value (or returns None)
[builtins fixtures/list.pyi]

[case testNoneReturnTypeWithExpressions2]
Expand All @@ -1117,14 +1117,14 @@ class A:

a: A
b: bool
f() in a # E: "f" does not return a value # E: Unsupported right operand type for in ("A")
a < f() # E: "f" does not return a value
f() <= a # E: "f" does not return a value
a in f() # E: "f" does not return a value
-f() # E: "f" does not return a value
not f() # E: "f" does not return a value
f() and b # E: "f" does not return a value
b or f() # E: "f" does not return a value
f() in a # E: "f" does not return a value (or returns None) # E: Unsupported right operand type for in ("A")
a < f() # E: "f" does not return a value (or returns None)
f() <= a # E: "f" does not return a value (or returns None)
a in f() # E: "f" does not return a value (or returns None)
-f() # E: "f" does not return a value (or returns None)
not f() # E: "f" does not return a value (or returns None)
f() and b # E: "f" does not return a value (or returns None)
b or f() # E: "f" does not return a value (or returns None)
[builtins fixtures/bool.pyi]


Expand Down Expand Up @@ -1424,7 +1424,7 @@ if int():
[case testConditionalExpressionWithEmptyCondition]
import typing
def f() -> None: pass
x = 1 if f() else 2 # E: "f" does not return a value
x = 1 if f() else 2 # E: "f" does not return a value (or returns None)

[case testConditionalExpressionWithSubtyping]
import typing
Expand Down Expand Up @@ -1487,7 +1487,7 @@ from typing import List, Union
x = []
y = ""
x.append(y) if bool() else x.append(y)
z = x.append(y) if bool() else x.append(y) # E: "append" of "list" does not return a value
z = x.append(y) if bool() else x.append(y) # E: "append" of "list" does not return a value (or returns None)
[builtins fixtures/list.pyi]

-- Special cases
Expand Down Expand Up @@ -1587,7 +1587,7 @@ def f(x: int) -> None:
[builtins fixtures/for.pyi]
[out]
main:1: error: The return type of a generator function should be "Generator" or one of its supertypes
main:2: error: "f" does not return a value
main:2: error: "f" does not return a value (or returns None)
main:2: error: Argument 1 to "f" has incompatible type "str"; expected "int"

[case testYieldExpressionWithNone]
Expand All @@ -1607,7 +1607,7 @@ from typing import Iterator
def f() -> Iterator[int]:
yield 5
def g() -> Iterator[int]:
a = yield from f() # E: Function does not return a value
a = yield from f() # E: Function does not return a value (or returns None)

[case testYieldFromGeneratorHasValue]
from typing import Iterator, Generator
Expand All @@ -1622,12 +1622,12 @@ def g() -> Iterator[int]:
[case testYieldFromTupleExpression]
from typing import Generator
def g() -> Generator[int, None, None]:
x = yield from () # E: Function does not return a value
x = yield from (0, 1, 2) # E: Function does not return a value
x = yield from () # E: Function does not return a value (or returns None)
x = yield from (0, 1, 2) # E: Function does not return a value (or returns None)
x = yield from (0, "ERROR") # E: Incompatible types in "yield from" (actual type "object", expected type "int") \
# E: Function does not return a value
# E: Function does not return a value (or returns None)
x = yield from ("ERROR",) # E: Incompatible types in "yield from" (actual type "str", expected type "int") \
# E: Function does not return a value
# E: Function does not return a value (or returns None)
[builtins fixtures/tuple.pyi]

-- dict(...)
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2 changes: 1 addition & 1 deletion test-data/unit/check-functions.test
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Expand Up @@ -250,7 +250,7 @@ if int():
if int():
f = o # E: Incompatible types in assignment (expression has type "object", variable has type "Callable[[], None]")
if int():
f = f() # E: Function does not return a value
f = f() # E: Function does not return a value (or returns None)

if int():
f = f
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8 changes: 4 additions & 4 deletions test-data/unit/check-inference.test
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Expand Up @@ -33,8 +33,8 @@ class B: pass
[case testLvarInitializedToVoid]
import typing
def f() -> None:
a = g() # E: "g" does not return a value
#b, c = g() # "g" does not return a value TODO
a = g() # E: "g" does not return a value (or returns None)
#b, c = g() # "g" does not return a value (or returns None) TODO

def g() -> None: pass
[out]
Expand Down Expand Up @@ -1180,7 +1180,7 @@ for e, f in [[]]: # E: Need type annotation for "e" \
[case testForStatementInferenceWithVoid]
def f() -> None: pass

for x in f(): # E: "f" does not return a value
for x in f(): # E: "f" does not return a value (or returns None)
pass
[builtins fixtures/for.pyi]

Expand Down Expand Up @@ -2118,7 +2118,7 @@ arr = []
arr.append(arr.append(1))
[builtins fixtures/list.pyi]
[out]
main:3: error: "append" of "list" does not return a value
main:3: error: "append" of "list" does not return a value (or returns None)

-- Multipass
-- ---------
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6 changes: 3 additions & 3 deletions test-data/unit/check-optional.test
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Expand Up @@ -361,9 +361,9 @@ def f() -> None:
def g(x: Optional[int]) -> int:
pass

x = f() # E: "f" does not return a value
f() + 1 # E: "f" does not return a value
g(f()) # E: "f" does not return a value
x = f() # E: "f" does not return a value (or returns None)
f() + 1 # E: "f" does not return a value (or returns None)
g(f()) # E: "f" does not return a value (or returns None)

[case testEmptyReturn]
def f() -> None:
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4 changes: 2 additions & 2 deletions test-data/unit/check-tuples.test
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Expand Up @@ -169,8 +169,8 @@ class C(B): pass
import typing
def f() -> None: pass

(None, f()) # E: "f" does not return a value
(f(), None) # E: "f" does not return a value
(None, f()) # E: "f" does not return a value (or returns None)
(f(), None) # E: "f" does not return a value (or returns None)
[builtins fixtures/tuple.pyi]


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4 changes: 2 additions & 2 deletions test-data/unit/check-varargs.test
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Expand Up @@ -52,8 +52,8 @@ c: C

f(c) # E: Argument 1 to "f" has incompatible type "C"; expected "A"
f(a, b, c) # E: Argument 3 to "f" has incompatible type "C"; expected "A"
f(g()) # E: "g" does not return a value
f(a, g()) # E: "g" does not return a value
f(g()) # E: "g" does not return a value (or returns None)
f(a, g()) # E: "g" does not return a value (or returns None)
f()
f(a)
f(b)
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2 changes: 1 addition & 1 deletion test-data/unit/pythoneval-asyncio.test
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Expand Up @@ -261,7 +261,7 @@ try:
finally:
loop.close()
[out]
_program.py:11: error: Function does not return a value
_program.py:11: error: Function does not return a value (or returns None)

[case testErrorReturnIsNotTheSameType]
from typing import Any
Expand Down
⚡