C++20 upgrade

[xezon]

Regarding C++20...

We have a situation. C++20 requires to make dependent names in templates explicit. Like so

Before

template<class T>
bool DynamicVectorClass<T>::Add(T const & object)
{
	if (ActiveCount >= Length()) {
		if ((IsAllocated || !VectorMax) && GrowthStep > 0) {
			if (!Resize(Length() + GrowthStep)) {
...

After

template<class T>
bool DynamicVectorClass<T>::Add(T const & object)
{
	if (This::ActiveCount >= This::Length()) {
		if ((This::IsAllocated || !This::VectorMax) && This::GrowthStep > 0) {
			if (!This::Resize(This::Length() + This::GrowthStep)) {
...

"This" is an alias:

template<class T>
class DynamicVectorClass : public VectorClass<T>
{
	typedef DynamicVectorClass<T> This;
...

Consequence

This will be

1. a lot of work
2. create a big diff, making merges to us more difficult when involving templates.

The good news is that this is compatible with VS6 as well.

Perhaps we should stick with c++17 for now? That would requires no further changes and make the transition easier.

On the other hand, if we update later, then we still need to retroactively apply this to all original and new code.

What do we do?

[DevGeniusCode]

What are the special advantages of C20 that make it recommended to upgrade to it rather than staying long-term on C17?

[OmniBlade]

Fairly sure this is required from C++17 as well is it not? You can solve it by changing the use of the variables to this->VarName, or by placing using statements in the class as done for Thyme https://github.com/TheAssemblyArmada/Thyme/blob/ccef1e11c1355c6db577a057c06e7d790f1a0333/src/w3d/lib/vector.h#L213

[xezon]

It is not required for C++17.

I used the typedef approach which works fine on VS6 too.

We need to decide if we want to do that. Technically it is ok, but complexity wise it is a problem.

[OmniBlade]

The "using" solution should also work with VC6 and results in a much smaller diff as the code itself doesn't need to be altered?

[xezon]

I will test that.

[xezon]

using approach works well.

[cfehunter]

I've been doing this for Renegade, in tandem with getting us working properly on x64, and it hasn't been too bad (check my github).
The closed source W3D version of Renegade also uses the using approach.

template
class Child : public Parent
{
using Parent::Bar;
}

[xezon]

This is solved.