Trying to construct a variant with a constant value type (i.e. the value is copied so the const doesn't matter) fails with a compiler error.

Example:

	import std.variant;

	alias Value = Algebraic!(long, double);

	void main() {
		const long foo = 123L;
		long bar = foo;
		Value baz = Value(foo);
	}

> rdmd ~/test.d
/usr/include/dmd/phobos/std/variant.d(544): Error: static assert  "Cannot store a const(long) in a VariantN!(8LU, long, double)"
/home/col/test.d(9):        instantiated from here: __ctor!(const(long))
Failed: ["dmd", "-v", "-o-", "/home/col/test.d", "-I/home/col"]

The same issue occurs if `foo` is immutable, or a double or boolean.

However, it does work with structs or slices:

	import std.variant;

	struct MyStruct { int a, b; }

	alias Value = Algebraic!(MyStruct, string);

	void main() {
		const MyStruct foo = MyStruct(1, 2);
		MyStruct bar = foo;
		Value baz = Value(foo);
		
		const string foo2 = "asdf";
		string bar2 = foo2;
		Value baz2 = Value(foo2);
	}