[Feature Request] Allow non-literal constants in attributes

[devshgraphicsprogramming]

Is your feature request related to a problem? Please describe.

I've tried numerous times to make the [[]vk::]] attributes depend on a template parameter or some other const expression, each time I thought its a general C++/Clang limitation.

#6541

#6584

Theres a few other issues I can't find right now which also showcased attempts at putting constant expressions into attributes.

But turns out its not: https://godbolt.org/z/he94bcGfr

Describe the solution you'd like

Being able to specify attribute arguments/parameters from constexpr (static const) variables and enums.

Describe alternatives you've considered

Nothing

Additional context

None

[pow2clk]

I'm not sure this is the link you intended to use as it demonstrates it working correctly in a C++ example. Given that there is some variability in this support, it would be useful to see which attributes are failing in the cases of interest.

[devshgraphicsprogramming]

Here's an example of what I'd like to be able to do:
https://godbolt.org/z/cMc1rdqn9