COMP: Make VariableLengthVector::AllocateElements ITK_FUTURE_DEPRECATED

[N-Dekker]

This member function is only marked ITK_FUTURE_LEGACY_REMOVE, so using this member function should only trigger a warning when legacy support is removed and ITK_LEGACY_SILENT is off.

Aims to fix warnings like:

itkVariableLengthVectorPython.cpp(5150): warning C4996: 'itk::VariableLengthVector::AllocateElements': Please consider calling `std::make_unique<TValue[]>(size)` instead.

At Windows_NT-Build4935-main-Python

• As reported by Matt McCormick (@thewtex) at pull request COMP: Suppress deprecated VariableLengthVector::AllocateElements warnings in MSVC wrapping builds #5863

[dzenanz]

When was this deprecated? If it made its way into a released version, we should probably not walk back its "full" deprecation.

[N-Dekker]

When was this deprecated? If it made its way into a released version, we should probably not walk back its "full" deprecation.

• It hasn't made its way into a released version. It was deprecated by pull request Remove AllocateElements from VariableLengthVector #5710 commit f080d4f, Dec 23, 2025 😇

[dzenanz]

But we have to eventually do a "full" deprecation. Will these warning not appear then?

[blowekamp]

But we have to eventually do a "full" deprecation. Will these warning not appear then?

I believe the expectation of ITK_LEGACY_SILENT is to suppress all deprecation warnings. This is useful for dashboard builds.

[N-Dekker]

But we have to eventually do a "full" deprecation. Will these warning not appear then?

There are 3 phases, right?

1. ITK_FUTURE_LEGACY_REMOVE: intended to become legacy-only with the next major release.
2. ITK_LEGACY_REMOVE: legacy-only (intended to be removed with the next major release)
3. Completely removed from ITK, unconditionally!

I think the warning should only appear for users who choose to make one step forward, by setting ITK_LEGACY_REMOVE = ON.

Once the functionality has become "legacy-only" (ITK_LEGACY_REMOVE), it becomes fully deprecated.

Right?

[dzenanz]

I am fine with the change, just making sure you though about these considerations.