BUG: SWIG typechecks reject foreign wrapped types

[dzenanz]

Based on code provided on the forum: https://discourse.itk.org/t/improper-wrapping-of-imagefunction-isinsidebuffer/7495

PR Checklist

• No API changes were made (or the changes have been approved)
• No major design changes were made (or the changes have been approved)
• Added test (or behavior not changed)
• Added Python wrapping to new files (if any) as described in ITK Software Guide Section 9.5

[Copilot]

Pull Request Overview

This pull request adds a new Python test file to verify the behavior of LinearImageFunction’s various IsInsideBuffer overloads as wrapped by ITK.

• Introduces a test script that exercises list, continuous index, and point-based inputs to IsInsideBuffer.
• Ensures that the Python wrapping for LinearImageFunction works as intended.

Files not reviewed (1)

• Modules/Core/ImageFunction/wrapping/test/CMakeLists.txt: Language not supported

[dzenanz]

On the CI, the test fails with a different error message:

Traceback (most recent call last):
  File "/Users/runner/work/ITK/ITK/Modules/Core/ImageFunction/wrapping/test/itkLinearImageFunctionWrappingTest.py", line 23, in <module>
    interp = itk.LinearInterpolateImageFunction.New(image)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/Users/runner/work/ITK/ITK/build/Wrapping/Generators/Python/itk/support/template_class.py", line 751, in New
    raise itk.TemplateTypeError(self, input_type)
itk.support.extras.TemplateTypeError: itk.LinearInterpolateImageFunction is not wrapped for input type `None`.

To limit the size of the package, only a limited number of
types are available in ITK Python. To print the supported
types, run the following command in your python environment:

    itk.LinearInterpolateImageFunction.GetTypes()

Possible solutions:
* If you are an application user:
** Convert your input image into a supported format (see below).
** Contact developer to report the issue.
* If you are an application developer, force input images to be
loaded in a supported pixel type.

    e.g.: instance = itk.LinearInterpolateImageFunction[itk.Image[itk.SS,2], itk.D].New(my_input)

* (Advanced) If you are an application developer, build ITK Python yourself and
turned to `ON` the corresponding CMake option to wrap the pixel type or image
dimension you need. When configuring ITK with CMake, you can set
`ITK_WRAP_${type}` (replace ${type} with appropriate pixel type such as
`double`). If you need to support images with 4 or 5 dimensions, you can add
these dimensions to the list of dimensions in the CMake variable
`ITK_WRAP_IMAGE_DIMS`.

Supported input types:

itk.Image[itk.SS,2]
itk.Image[itk.UC,2]
itk.Image[itk.F,2]
itk.Image[itk.Vector[itk.F,2],2]
itk.Image[itk.CovariantVector[itk.F,2],2]
itk.Image[itk.RGBPixel[itk.UC],2]
itk.Image[itk.RGBAPixel[itk.UC],2]
itk.Image[itk.SS,3]
itk.Image[itk.UC,3]
itk.Image[itk.F,3]
itk.Image[itk.Vector[itk.F,3],3]
itk.Image[itk.CovariantVector[itk.F,3],3]
itk.Image[itk.RGBPixel[itk.UC],3]
itk.Image[itk.RGBAPixel[itk.UC],3]
itk.PhasedArray3DSpecialCoordinatesImage[itk.F]
itk.PhasedArray3DSpecialCoordinatesImage[itk.UC]

itkTestDriver: Process exited with return value: 1

[hjmjohnson]

Found the root cause and pushed a fix to this branch (bdbe9ae6c3).

The bug isn't specific to IsInsideBuffer — it's in the SWIG typecheck typemaps in Wrapping/Generators/Python/PyBase/pyBase.i. All wrapped fixed-length ITK classes (Index, ContinuousIndex, Point, Vector, FixedArray, ...) expose __getitem__ / __len__ for ergonomic indexing. The typecheck typemaps for those types treated any object satisfying PySequence_Check and the right length as a viable match — so a wrapped ContinuousIndex looked like a valid Index argument, and SWIG's overload dispatcher always committed to the first overload (Index) before ever evaluating ContinuousIndex or Point.

The fix tightens those typechecks so they (a) accept native pointer matches, (b) reject SWIG wrappers of unrelated types via SWIG_Python_GetSwigThis, and (c) for the int-only Index/Size/Offset typemap, peek at element 0 to reject float-element sequences. Your test (now adapted to use assert) passes for all four documented call patterns.

[greptile-apps]

Greptile Summary

This PR fixes a long-standing SWIG overload-dispatch bug (IsInsideBuffer and similar methods always selected the Index overload regardless of input type) by tightening the typecheck typemaps in pyBase.i. The fix explicitly rejects SWIG-wrapped objects of unrelated types (which previously satisfied PySequence_Check via their __getitem__/__len__) and adds an element-type peek for integer-only (Index) typemaps to reject float sequences. A new Python regression test covering all three overload paths (Index, ContinuousIndex, Point) is added and wired into CMake.

Confidence Score: 4/5

Safe to merge; the typecheck fix is logically sound and the regression test validates all key overload paths.

No P0 or P1 issues found. The SWIG typemap changes correctly handle the four affected macros consistently, and PyErr_Clear usage around the element-peek is appropriate. Only minor style-level observations remain.

Wrapping/Generators/Python/PyBase/pyBase.i — broad impact on all Python-wrapped types using these typemap macros, worth a careful build + test run.

Important Files Changed

Filename	Overview
Wrapping/Generators/Python/PyBase/pyBase.i	Fixes SWIG typecheck typemaps in four macros to reject unrelated wrapped types via SWIG_Python_GetSwigThis and adds element-type peeking for integer-only (Index) typechecks; logic is correct and consistent across all four affected macros.
Modules/Core/ImageFunction/wrapping/test/itkLinearImageFunctionWrappingTest.py	New regression test covering all four IsInsideBuffer overload paths (raw int list, ContinuousIndex, Point, raw float list) plus out-of-buffer False cases; follows established ITK Python test patterns.
Modules/Core/ImageFunction/wrapping/test/CMakeLists.txt	Adds itk_python_add_test registration for the new test script; follows existing patterns in this file.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Python calls IsInsideBuffer with any input] --> B{SWIG_ConvertPtr\nsucceeds for this type?}
    B -- yes --> C[_v = 1\nOverload candidate]
    B -- no --> D[PyErr_Clear]
    D --> E{SWIG_Python_GetSwigThis\nnot NULL?\nUnrelated wrapped type}
    E -- yes --> F[_v = 0\nReject candidate]
    E -- no --> G{For VEC typemap:\nPyInt/Float_Check?}
    G -- yes --> H[_v = 1\nOverload candidate]
    G -- no --> I{PySequence_Check\nAND length == dim?}
    I -- no --> F2[_v = 0\nReject candidate]
    I -- yes --> J{INT_INDEX typemap only:\nPeek element 0\nPyInt or PyLong?}
    J -- yes --> K[_v = 1\nOverload candidate]
    J -- no --> F3[_v = 0\nReject candidate]

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_{Reviews (1): Last reviewed commit: "BUG: SWIG typechecks reject foreign wrap..." | Re-trigger Greptile}

[dzenanz]

Looks good on a glance. I can't approve my own PR.

[hjmjohnson]

I'm addressing the greptile with a minor test addition.