Why does calling a struct constructor generate linker errors when using Better C?

[Stijn]

https://dlang.org/spec/betterc.html doesn't mention struct 
constructors not working, but I'm getting linker errors when 
trying to call a struct constructor.

Consider the following program betterc.d

     struct foo
     {
     }

     extern(C) void main()
     {
         auto bar = new foo();
     }

Compile with: dmd -c -m32 betterc.d -betterC
Link with: gcc -m32 betterc.o -Wl,--build-id=none -nostdlib -o 
"betterc.bin"

Linker output:

     betterc.o: In function `main':
     betterc.d:(.text.main[main]+0xa): undefined reference to 
`_d_newitemT'
     betterc.o:(.data._D22TypeInfo_S7betterc3foo6__initZ+0x0): 
undefined reference to `_D15TypeInfo_Struct6__vtblZ'
     collect2: error: ld returned 1 exit status

Is there a mistake in my code, or is the documentation lacking?