Link error with template struct on 2.042

[Frank Fischer]

Hi,

after some time I started again playing with D. The following example
gives an error I don't understand (I'm trying dmd 2.042):

==== main.d ====
import MyMod;

void main()
{
    MyStruct!(int) s;
}

==== MyMod.d ===
module MyMod;

struct MyStruct(T) {
    this(this) {}
}
================

If I compile the above example with

dmd main.d

I get the following error:

main.o: In function
`_D5MyMod15__T8MyStructTiZ8MyStruct10__postblitMFZv':
main.d:(.text._D5MyMod15__T8MyStructTiZ8MyStruct10__postblitMFZv+0x12):
undefined reference to `_D5MyMod8__assertFiZv'
main.o: In function
`_D5MyMod15__T8MyStructTiZ8MyStruct8opAssignMFNcS5MyMod15__T8MyStructTiZ8MyStructZS5MyMod15__T8MyStructTiZ8MyStruct':
main.d:(.text._D5MyMod15__T8MyStructTiZ8MyStruct8opAssignMFNcS5MyMod15__T8MyStructTiZ8MyStructZS5MyMod15__T8MyStructTiZ8MyStruct+0x12):
undefined reference to `_D5MyMod8__assertFiZv'
collect2: ld returned 1 exit status
--- errorlevel 1

What does this mean? Note that everything works fine if MyStruct is
not a template, if there's no function this(this) or if I compile the
example with assertions disabled like this:

dmd -release main.d

It seems as I'm missing to implement some function, but I don't know
which.

Thanks in advance
Frank