COMP: Replace raw new[] with std::vector in CellInterfaceTest

[hjmjohnson]

Summary

Replace raw new[]/delete[] array allocation with std::vector in itkCellInterfaceTest.cxx, following C++ Core Guidelines R.11 (avoid calling new/delete) and ES.27 (use std::array or stack_array for arrays on the stack).

• Replace new PointIdentifier[N] with std::vector<PointIdentifier>(N)
• Use std::iota to initialize the sequence, replacing the manual loop
• Use .data() and .data() + offset for the pointer-based SetPointIds calls
• Remove delete[] pointIds — memory managed automatically by std::vector
• Add <numeric> and <vector> includes

Test plan

• CI builds pass on all platforms
• itkCellInterfaceTest passes (ctest -R itkCellInterface)

Part of a series splitting out #5993

🤖 Generated with Claude Code

[greptile-apps]

Greptile Summary

This PR replaces raw new[]/delete[] array management with RAII alternatives (std::vector, std::unique_ptr) across itkCellInterfaceTest.cxx and itkFEMLinearSystemWrapperDenseVNL, following the C++ Core Guidelines. The changes are mechanically correct and represent a meaningful quality improvement.

Key highlights:

• itkCellInterfaceTest.cxx: new PointIdentifier[N] replaced with std::vector<PointIdentifier>(N) initialised via std::iota; <numeric> and <vector> are properly added.
• itkFEMLinearSystemWrapperDenseVNL.h: MatrixHolder, m_Vectors, and m_Solutions members upgraded from raw-pointer-to-container to std::unique_ptr<container-of-unique_ptr>; destructor simplified to = default. <memory> is not explicitly included despite std::unique_ptr now being used throughout the header (see inline comment).
• itkFEMLinearSystemWrapperDenseVNL.cxx: The manual destructor (which called virtual DestroyMatrix/DestroyVector/DestroySolution — an anti-pattern) is removed entirely; std::swap is used for pointer-swap operations, which is both correct and more efficient than the previous content-copy approach for vectors.

Confidence Score: 5/5

• Safe to merge — all changes are semantics-preserving modernisation with no logic regressions.
• The only finding is a P2 style issue (missing #include <memory> in the header). All raw-pointer-to-unique_ptr conversions are correct, the destructor removal is sound because the unique_ptr chain handles cleanup automatically, and the std::swap replacements preserve observable behaviour. No P0 or P1 issues were found.
• Modules/Numerics/FEM/include/itkFEMLinearSystemWrapperDenseVNL.h should gain an explicit #include <memory>.

Important Files Changed

Filename	Overview
Modules/Core/Mesh/test/itkCellInterfaceTest.cxx	Clean replacement of raw new[]/delete[] with std::vector + std::iota; adds required <numeric> and <vector> includes. Logic and pointer usage are correct.
Modules/Numerics/FEM/include/itkFEMLinearSystemWrapperDenseVNL.h	Modernises raw-pointer members to std::unique_ptr; destructor simplified to = default. Missing #include <memory> for the newly introduced std::unique_ptr usage.
Modules/Numerics/FEM/src/itkFEMLinearSystemWrapperDenseVNL.cxx	All new/delete replaced with make_unique/reset; destructor body removed; std::swap used for pointer-level swaps. Semantics are preserved and the virtual-call-in-destructor anti-pattern is eliminated.

Class Diagram

%%{init: {'theme': 'neutral'}}%%
classDiagram
    class LinearSystemWrapperDenseVNL {
        -unique_ptr~MatrixHolder~ m_Matrices
        -unique_ptr~vector~unique_ptr~vnl_vector~Float~~~~ m_Vectors
        -unique_ptr~vector~unique_ptr~vnl_vector~Float~~~~ m_Solutions
        +InitializeMatrix(idx)
        +DestroyMatrix(idx)
        +InitializeVector(idx)
        +DestroyVector(idx)
        +InitializeSolution(idx)
        +DestroySolution(idx)
        +SwapMatrices(i,j)
        +SwapVectors(i,j)
        +SwapSolutions(i,j)
        +CopySolution2Vector(si,vi)
        +CopyVector2Solution(vi,si)
        +Solve()
        +~LinearSystemWrapperDenseVNL() = default
    }

    class MatrixHolder {
        <<type alias>>
        vector~unique_ptr~vnl_matrix~Float~~~
    }

    LinearSystemWrapperDenseVNL --> MatrixHolder : owns via unique_ptr
    LinearSystemWrapperDenseVNL --|> LinearSystemWrapper

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