When in a namespace, function like keywords at start of line is tagged as a constructor.

[matter123]

Example code:

namespace {
	using A = decltype(5);
	decltype(5) B = A();
}

This effects decltype, static_assert, template deduction guides (migh not be incorrect however), some macros.
This is because the namespace pattern includes :constructors before $base.

Removing :constructors seems to have almost no negative side effects. (One exception is test::test(){} is not tagged as a constructor, it is also not tagged outside of a namespace currently as well, so a better solution should be found). I cannot think of why constructors should be treated differently inside/outside a namespace.