Regular Templates May Be `mixin`d?

[Paul Backus]

On Sunday, 3 October 2021 at 02:52:20 UTC, surlymoor wrote:
> This compiles and works. I checked the spec, and I don't see 
> anything; probably missed it, however; mentioning the fact that 
> regular templates may be used with `mixin`. Is this expected?

Yes, this is intentional and expected. From the spec:

> A TemplateMixin takes an arbitrary set of declarations from the 
> body of a TemplateDeclaration and inserts them into the current 
> context.

Source: https://dlang.org/spec/template-mixin.html

Notice that it is specified to work with any template 
declaration, not just one declared as a `mixin template`.