Fixed bug that results in incorrect inferred type for an instance or …

[erictraut]

…class variable assigned a value as part of a tuple expression target with an unpack operator (e.g. a, *self.b = (1, 2, 3)). This addresses #9841.

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

sympy (https://github.com/sympy/sympy)
+   /tmp/mypy_primer/projects/sympy/sympy/vector/dyadic.py:233:7 - error: Base classes for class "DyadicMul" define method "as_content_primitive" in incompatible way
+     Return type mismatch: base method returns type "tuple[One, Self@Expr]", override returns type "tuple[One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Unknown, Self@Mul]"
+       "tuple[One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Unknown, Self@Mul]" is not assignable to "tuple[One, Self@Expr]"
+         Tuple entry 1 is incorrect type
+           Type "One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Unknown" is not assignable to type "One"
+             "ComplexInfinity" is not assignable to "One" (reportIncompatibleMethodOverride)
-     Return type mismatch: base method returns type "tuple[Expr, Expr]", override returns type "tuple[Self@Mul, Zero] | tuple[Zero, Expr] | tuple[Expr, Expr] | tuple[Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | _NotImplementedType, Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | _NotImplementedType] | tuple[Expr | Any | Unknown, Expr | Any | Unknown] | tuple[Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number, Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number] | None"
+     Return type mismatch: base method returns type "tuple[Expr, Expr]", override returns type "tuple[Self@Mul, Zero] | tuple[Zero, Expr] | tuple[Expr, Expr] | tuple[Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Unknown, Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Unknown] | tuple[Expr | Any | Unknown, Expr | Any | Unknown] | tuple[Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number, Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number] | None"
-       Type "tuple[Self@Mul, Zero] | tuple[Zero, Expr] | tuple[Expr, Expr] | tuple[Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | _NotImplementedType, Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | _NotImplementedType] | tuple[Expr | Any | Unknown, Expr | Any | Unknown] | tuple[Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number, Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number] | None" is not assignable to type "tuple[Expr, Expr]"
+       Type "tuple[Self@Mul, Zero] | tuple[Zero, Expr] | tuple[Expr, Expr] | tuple[Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Unknown, Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Unknown] | tuple[Expr | Any | Unknown, Expr | Any | Unknown] | tuple[Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number, Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number] | None" is not assignable to type "tuple[Expr, Expr]"
+   /tmp/mypy_primer/projects/sympy/sympy/vector/dyadic.py:253:7 - error: Base classes for class "DyadicAdd" define method "as_content_primitive" in incompatible way
+     Return type mismatch: base method returns type "tuple[One, Self@Expr]", override returns type "tuple[One | NegativeOne | Zero | Integer | Expr | ComplexInfinity | Rational | NaN | Half | Unknown, Expr | Unknown | Self@Add]"
+       "tuple[One | NegativeOne | Zero | Integer | Expr | ComplexInfinity | Rational | NaN | Half | Unknown, Expr | Unknown | Self@Add]" is not assignable to "tuple[One, Self@Expr]"
+         Tuple entry 1 is incorrect type
+           Type "One | NegativeOne | Zero | Integer | Expr | ComplexInfinity | Rational | NaN | Half | Unknown" is not assignable to type "One"
+             "Expr" is not assignable to "One" (reportIncompatibleMethodOverride)
-   /tmp/mypy_primer/projects/sympy/sympy/vector/implicitregion.py:114:20 - error: Operator "**" not supported for "None" (reportOptionalOperand)
-   /tmp/mypy_primer/projects/sympy/sympy/vector/implicitregion.py:114:28 - error: Operator "*" not supported for types "Literal[4]" and "One | Zero | Expr | Unknown | Any | None"
-     Operator "*" not supported for types "Literal[4]" and "None" (reportOperatorIssue)
-   /tmp/mypy_primer/projects/sympy/sympy/vector/implicitregion.py:503:30 - error: "coeff" is not a known attribute of "None" (reportOptionalMemberAccess)
-   /tmp/mypy_primer/projects/sympy/sympy/vector/implicitregion.py:504:30 - error: "coeff" is not a known attribute of "None" (reportOptionalMemberAccess)
-   /tmp/mypy_primer/projects/sympy/sympy/vector/implicitregion.py:505:30 - error: "coeff" is not a known attribute of "None" (reportOptionalMemberAccess)
+   /tmp/mypy_primer/projects/sympy/sympy/vector/vector.py:496:7 - error: Base classes for class "VectorAdd" define method "as_content_primitive" in incompatible way
+     Return type mismatch: base method returns type "tuple[One, Self@Expr]", override returns type "tuple[One | NegativeOne | Zero | Integer | Expr | ComplexInfinity | Rational | NaN | Half | Unknown, Expr | Unknown | Self@Add]"
+       "tuple[One | NegativeOne | Zero | Integer | Expr | ComplexInfinity | Rational | NaN | Half | Unknown, Expr | Unknown | Self@Add]" is not assignable to "tuple[One, Self@Expr]"
+         Tuple entry 1 is incorrect type
+           Type "One | NegativeOne | Zero | Integer | Expr | ComplexInfinity | Rational | NaN | Half | Unknown" is not assignable to type "One"
+             "Expr" is not assignable to "One" (reportIncompatibleMethodOverride)
+   /tmp/mypy_primer/projects/sympy/sympy/vector/vector.py:518:7 - error: Base classes for class "VectorMul" define method "as_content_primitive" in incompatible way
+     Return type mismatch: base method returns type "tuple[One, Self@Expr]", override returns type "tuple[One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Unknown, Self@Mul]"
+       "tuple[One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Unknown, Self@Mul]" is not assignable to "tuple[One, Self@Expr]"
+         Tuple entry 1 is incorrect type
+           Type "One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Unknown" is not assignable to type "One"
+             "ComplexInfinity" is not assignable to "One" (reportIncompatibleMethodOverride)
-     Return type mismatch: base method returns type "tuple[Expr, Expr]", override returns type "tuple[Self@Mul, Zero] | tuple[Zero, Expr] | tuple[Expr, Expr] | tuple[Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | _NotImplementedType, Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | _NotImplementedType] | tuple[Expr | Any | Unknown, Expr | Any | Unknown] | tuple[Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number, Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number] | None"
+     Return type mismatch: base method returns type "tuple[Expr, Expr]", override returns type "tuple[Self@Mul, Zero] | tuple[Zero, Expr] | tuple[Expr, Expr] | tuple[Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Unknown, Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Unknown] | tuple[Expr | Any | Unknown, Expr | Any | Unknown] | tuple[Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number, Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number] | None"
-       Type "tuple[Self@Mul, Zero] | tuple[Zero, Expr] | tuple[Expr, Expr] | tuple[Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | _NotImplementedType, Expr | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | _NotImplementedType] | tuple[Expr | Any | Unknown, Expr | Any | Unknown] | tuple[Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number, Expr | Any | Unknown | One | NegativeOne | Zero | Integer | Rational | NaN | ComplexInfinity | Half | Infinity | NegativeInfinity | Float | Number] | None" is not assignable to type "tuple[Expr, Expr]"

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