BUG: Validate TileImageFilter Layout has no zero before the last axis

[physwkim]

TileImageFilter never validates Layout: a 0 in any axis but the last indexes an empty std::vector and runs a loop of about 2^32 iterations, and the constructor's own all-zero default divides by zero. Addresses B87 of #6575.

Root cause and fix

Only the last axis of Layout may be 0 (meaning "as many tiles as needed"); a 0 anywhere else is meaningless, and the tile-index arithmetic in GenerateData() has no defense against it. Rather than guarding each use site, VerifyPreconditions() now rejects a zero in any non-last axis, so GenerateData() cannot be reached with an unusable layout.

Local validation

Two cases added to itkTileImageFilterGTest.cxx:

• RejectsZeroInNonLastLayoutAxis — fail-before: no exception (then UB). Pass-after: throws.
• RejectsDefaultZeroLayout — same, for the constructor default.

ctest -L ImageGrid: 69/69 pass, unchanged.

AI assistance

• Tool: Claude Code
• Role: implementation and regression-test authoring from the analysis in BUG: Findings collected while porting ~60 filters — reported together in one issue #6575
• All code was reviewed, built, and tested locally before committing

[greptile-apps]

Greptile Summary

This PR adds layout validation to TileImageFilter. The main changes are:

• Adds a VerifyPreconditions() override for the filter.
• Rejects zero layout entries before the last output axis.
• Adds tests for explicit non-last zero layout and default zero layout.

Confidence Score: 5/5

This looks safe to merge.

No blocking issues found in the changed code.

No files need attention.

T-Rex Logs

What T-Rex did

• The tool-detection pass confirmed CMake and CTest are unavailable while g++ and make are available.
• The narrow CMake configure attempt and the cmake-not-found blocker were reviewed from the CMake configure log.
• The PR test file was verified to include RejectsZeroInNonLastLayoutAxis and RejectsDefaultZeroLayout as shown in the test-presence log.
• Before/after runtime evidence was captured from the compiled C++ harnesses.

_{Ran code and verified through T-Rex}

Important Files Changed

Filename	Overview
Modules/Filtering/ImageGrid/include/itkTileImageFilter.h	Declares the new precondition hook for layout validation.
Modules/Filtering/ImageGrid/include/itkTileImageFilter.hxx	Rejects zero layout entries in non-last dimensions before output generation.
Modules/Filtering/ImageGrid/test/itkTileImageFilterGTest.cxx	Adds tests for invalid zero-layout configurations.

_{Reviews (2): Last reviewed commit: "BUG: Validate Layout has no zero before ..." | Re-trigger Greptile}