Debug prints in @nogc

[Nordlöw via Digitalmars-d-learn]

I'm struggling with debug printing in my @nogc-containers.
The alternatives:

    assert(false, "Fixed message with no parameters");

is not enough for my needs

    debug writeln("Fixed");

doesn't bypass @nogc checking. Why?

And temporary commenting out @nogc is cumbersome.

I'm aware of C-style printf but that is not as flexible as 
writeln.

Any advice?