complex number support

[Walter Bright]

On 2/4/2026 8:58 AM, Iain Buclaw wrote:
> I've mentioned this before.  I might be open to reintroducing complex into the 
> language as `__complex(float)` et al. so that it falls into the specialized 
> category of types that aren't guaranteed to always be supported (whilst at the 
> same time freeing up the old keywords to use as an identifier)
> 
> We already have the means to test whether `__vector(T)` is supported on a given 
> target, the same style hooks can be used for `__complex(T)`.

Complex will always have to be supported because of C.

The vector types have a lot of specific code generator support. I have deferred 
investigating how to implement it for AArch64 until everything else is working.