STYLE: Replace Fill calls with auto var = itk::MakeFilled<T> in tests

[N-Dekker]

Replaced code of the form

T var;
var.Fill(x);

with auto var = itk::MakeFilled<T>(x);

Following C++ Core Guidelines, Oct 3, 2024, "Always initialize an object", https://isocpp.github.io/CppCoreGuidelines/CppCoreGuidelines#Res-always

Using Notepad++, Replace in Files, doing:

Find what: ^( [ ]+)([^ ].*)[ ]+(\w+);[\r\n]+\1\3\.Fill\(
Replace with: $1auto $3 = itk::MakeFilled<$2>\(
Filters: itk*Test*.cxx
[v] Match case
(*) Regular expression

Follow-up to

• pull request STYLE: Replace Fill(0) with {} initializer for local variables in tests #4881
• pull request STYLE: Replace Fill(0.) and Fill(0u) with {} initializer for local variables in tests #4884
• pull request Replace Fill(T{}) with {} initialization, replace T var; var.Fill with auto var = T::Filled in tests #4887

[dzenanz]

Looks good on a glance.

[N-Dekker]

Honestly I find the syntax auto var = itk::MakeFilled<T>(x) a bit verbose. For zero-filling I would certainly prefer the syntax T var{}. But I still think auto var = itk::MakeFilled<T>(x) is very much preferable to declaring the variable uninitialized and calling Fill afterwards.

As a follow-up, the variable might in some cases be declared constexpr:

    // Assuming that the fill value x is also a compile-time constant:
    constexpr auto var = itk::MakeFilled<T>(x); 

😃

[N-Dekker]

Hmmm, compilers don't like itk::MakeFilled for an itk::Matrix. 🤔 To be continued...

---

Let's postpone this pull request until after the following two have been processed:

• pull request STYLE: Replace Fill(static_cast<RealType>(0.0)) with {} in test #4893
• pull request ENH: Add STL-style iterators and size() member function to itk::Matrix #4894