Expand View getSubView host coverage

[psychocoderHPC]

Split from local commit 5de5bfd.

Base branch: dev.

Summary by CodeRabbit

Release Notes

• Bug Fixes

  • MdForwardIter now correctly initializes to end state when any dimension extent is zero, ensuring proper iterator comparison for empty spans.

• New Features

  • Added const overloads for begin()/end() methods in MdSpan and MdSpanArray for improved const-correctness in iteration.

• Tests

  • Expanded iterator and subview test coverage with comprehensive edge-case validation including empty extents, iteration order, and memory layout preservation.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: 4408c360-d557-439f-bd5e-89400dcb75f5

📥 Commits

Reviewing files that changed from the base of the PR and between 5de5bfd and e8639ff.

📒 Files selected for processing (2)

• include/alpaka/mem/MdForwardIter.hpp
• test/unit/mem/subDataStorage.cpp

📝 Walkthrough

Walkthrough

The changes fix iterator behavior for multi-dimensional spans with empty dimensions and enhance const-correctness. MdForwardIter now initializes to end state when any extent is zero. MdSpan and MdSpanArray add explicit const overloads for begin/end methods to ensure const-propagated iteration. Comprehensive tests validate iterator semantics, range iteration edge cases, and subview functionality.

Changes

Cohort / File(s)	Summary
Multi-dimensional iterator and span refinements include/alpaka/mem/MdForwardIter.hpp, include/alpaka/mem/MdSpan.hpp, include/alpaka/mem/MdSpanArray.hpp	Modified MdForwardIter constructor to initialize to end state when any dimension extent is zero. Added explicit const overloads for begin()/end() methods in MdSpan and MdSpanArray to ensure const-propagated span iteration.
Iterator and range behavior tests test/unit/mem/idxRange.cpp, test/unit/mem/mdIterator.cpp, test/unit/mem/subDataStorage.cpp	Added comprehensive host-side tests for IdxRange edge cases, MdSpan/View iterator behavior (including zero-extent, const-correctness, and forward-iterator semantics), and subview offset aliasing with memory layout contract validation.
Regression test update test/unit/mem/concepts.cpp	Updated pitch calculation test to use NonCopyStruct element type, aligning type derivation with non-copyable element scenarios.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

🐰 When spans lie empty, iterators once would stray,
But now they find the end without delay—
With const-correctness blooming everywhere,
These bouncing changes show the utmost care! ✨🎉

🚥 Pre-merge checks | ✅ 2 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (2 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The PR title 'Expand View getSubView host coverage' directly aligns with the main changes, which add comprehensive unit-test coverage for alpaka::View::getSubView across 1D and 3D cases with host-side testing.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch pr-expand-view-getsubview-host-coverage

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[psychocoderHPC]

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[psychocoderHPC]

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