8000 Fixed a bug that led to a false positive error when calling a constru… · sourcegraph/scip-python@8f401e3 · GitHub
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Fixed a bug that led to a false positive error when calling a constructor using bidirectional type inference on a generic class that defines a __new__ method but no __init__ method. This addresses microsoft/pyright#4890.
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3 files changed

+59
-5
lines changed

3 files changed

+59
-5
lines changed

‎packages/pyright-internal/src/analyzer/typeEvaluator.ts

Lines changed: 7 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -8625,7 +8625,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
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initMethodType
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);
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8628-
if (expectedCallResult) {
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if (expectedCallResult && !expectedCallResult.argumentErrors) {
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returnType = expectedCallResult.returnType;
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if (expectedCallResult.isTypeIncomplete) {
@@ -8725,6 +8725,7 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
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if (constructorMethodInfo && !skipConstructorCheck(constructorMethodInfo.type)) {
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const constructorMethodType = constructorMethodInfo.type;
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let newReturnType: Type | undefined;
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// If there is an expected type that was not applied above when
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// handling the __init__ method, try to apply it with the __new__ method.
@@ -8738,8 +8739,9 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
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constructorMethodType
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);
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8741-
if (expectedCallResult) {
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returnType = expectedCallResult.returnType;
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if (expectedCallResult && !expectedCallResult.argumentErrors) {
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newReturnType = expectedCallResult.returnType;
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returnType = newReturnType;
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if (expectedCallResult.isTypeIncomplete) {
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isTypeIncomplete = true;
@@ -8786,8 +8788,8 @@ export function createTypeEvaluator(importLookup: ImportLookup, evaluatorOptions
87868788

87878789
if (callResult.argumentErrors) {
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reportedErrors = true;
8789-
} else {
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let newReturnType = callResult.returnType;
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} else if (!newReturnType) {
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newReturnType = callResult.returnType;
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// If the constructor returned an object whose type matches the class of
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// the original type being constructed, use the return type in case it was

‎packages/pyright-internal/src/tests/samples/constructor15.py

Lines changed: 46 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,46 @@
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# This sample tests the case where a constructor for a generic
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# class is called with an inference context (i.e. using bidirectional
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# type inference) and literals are used as type arguments.
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from typing import Any, Generic, Literal, Self, TypeVar
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_N = TypeVar("_N")
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_M = TypeVar("_M")
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class A(Generic[_M, _N]):
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def __new__(cls, m: _M, n: _N) -> "A[_M, _N]":
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...
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a: A[Literal[3], Literal[4]] = A(3, 4)
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class B(Generic[_M, _N]):
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def __new__(cls, m: _M, n: _N) -> A[_M, _N]:
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...
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def __init__(self, *args: Any, **kwargs: Any) -> None:
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...
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b: B[Literal[3], Literal[4]] = B(3, 4)
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class C(Generic[_M, _N]):
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def __new__(cls, m: _M, n: _N) -> A[_M, _N]:
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...
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def __init__(self, m: _M, n: _N) -> None:
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...
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c: C[Literal[3], Literal[4]] = C(3, 4)
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class D(Generic[_M, _N]):
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def __new__(cls, m: _M, n: _N) -> Self:
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...
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d: D[Literal[3], Literal[4]] = D(3, 4)

‎packages/pyright-internal/src/tests/typeEvaluator3.test.ts

Lines changed: 6 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -1358,6 +1358,12 @@ test('Constructor14', () => {
13581358
TestUtils.validateResults(analysisResults, 0);
13591359
});
13601360

1361+
test('Constructor15', () => {
1362+
const analysisResults = TestUtils.typeAnalyzeSampleFiles(['constructor15.py']);
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1364+
TestUtils.validateResults(analysisResults, 0);
1365+
});
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13611367
test('InconsistentConstructor1', () => {
13621368
const configOptions = new ConfigOptions('.');
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