Given the following module:

------------------
module tos;

import std.string : to;
import std.stdio : writeln;

void dotos()
{
	const char* str = "Foo";
	writeln(to!string(str));
}
------------------

Compile with:
dmd -lib tos.d

Then take this module:

------------------
module tosmain;

import tos;

void main()
{
	dotos();
}
------------------

And compile with:
dmd tos.lib tosmain.d

The output is the following:

OPTLINK (R) for Win32  Release 8.00.2
Copyright (C) Digital Mars 1989-2009  All rights reserved.
http://www.digitalmars.com/ctg/optlink.html
tos.lib
 Warning 140: Library probably needs FIXLIB

However, in my Derelict libraries, I have a utility function that wraps to!string to convert from a C string to a D string, but this warning is not given when linking with that lib. I've been unable to reproduce it in a small test case for comparison, as I keep getting this warning no matter what I do. Regardless, the output of the program is unaffected.