Fix property access for function types

[daleselaji-dev]

Problem

Mypy treats a property returning types.FunctionType as a bound method when the value is accessed from an instance. A valid isinstance(..., FunctionType) assertion is therefore reported as an impossible intersection with MethodType when --warn-unreachable is enabled.

Root Cause

After resolving a property getter, member analysis applies descriptor access again to the getter's returned value. That second descriptor pass binds the returned FunctionType as if it were the class attribute itself.

Solution

Skip the post-property descriptor pass. Descriptor handling has already been applied to the property getter; the value returned by a property must be treated as the value, even when that value implements the descriptor protocol.

Changes

• Avoided second descriptor binding for property results in analyze_var.
• Added a focused type-check test and a minimal types.FunctionType/MethodType fixture.

Testing

• Reproduction before fix: current main revealed wrapped.__func__ as types.MethodType and emitted two [unreachable] errors.
• Focused regression: pytest -n0 mypy/test/testcheck.py -k testPropertyReturningFunctionType — 1 passed.
• Full check-classes.test: 610 passed, 1 existing xfailed.
• Self typecheck: python -m mypy --config-file mypy_self_check.ini -p mypy — 196 source files, no issues.
• Black formatted the changed Python source; git diff --check passed.
• Repository pre-commit was attempted but its first-run hook environments were still bootstrapping in this Windows environment; it is not claimed as passed.

Compatibility/Risk

Only property access is changed. Methods, ordinary descriptors, and direct class-attribute descriptor access retain their existing analysis. The fix prevents a false-positive narrowing error without changing runtime semantics.

Notes for Reviewer

The test specifically models the reported FunctionType/MethodType final-class intersection and verifies that the property result remains FunctionType.

Linked Issue

Fixes #21879

[github-actions]

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

colour (https://github.com/colour-science/colour)
- colour/continuous/signal.py:1207: error: Argument 1 to "as_float_array" has incompatible type "ndarray[tuple[int], dtype[Any]] | ExtensionArray"; expected "Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | complex | bytes | str | _NestedSequence[complex | bytes | str]"  [arg-type]
+ colour/continuous/signal.py:1207: error: Argument 1 to "as_float_array" has incompatible type "ndarray[tuple[int], dtype[Any]] | ExtensionArray | Categorical[object]"; expected "Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | complex | bytes | str | _NestedSequence[complex | bytes | str]"  [arg-type]

freqtrade (https://github.com/freqtrade/freqtrade)
+ freqtrade/freqai/freqai_interface.py:950: error: Argument 1 to "to_datetime" has incompatible type "Any | object"; expected "float | str | datetime | datetime64[Any] | date"  [arg-type]