Fix `rfl::DefaultVal` with `rfl::Rename`

[cacharle]

I have the following toml file:

foo = true

and cpp code:

struct Config {
    rfl::DefaultVal<rfl::Rename<"foo", bool>> Foo = false;
};

auto config = rfl::toml::load("config.toml").value();
std::println("> {}", config.Foo.get().get());

This prints false.

Am I missing something about how to compose those things or is it just not possible? I haven't tried anything else than TOML so I'm not sure if it's related to the format or not.

[liuzicheng1987]

@cacharle it is possible that wrapping rename in default_var voids the rename. If so, it's certainly not specific to TOML and something we should take a look at.

For the time being, you could use the DefaultIfMissing preprocessor instead of DefaultVar.

[liuzicheng1987]

@cacharle I have taken a look at this and found that it is quite easy to fix.

#589

Basically, after the PR is merged, you will be able to write this:

struct Config {
    rfl::Rename<"foo", rfl::DefaultVal<bool>> Foo = false;
};

This will then work as expected.

[cacharle]

That's nice, thanks a lot