undefined reference - Derelict2

[sergeiV]

On Sunday, 6 May 2012 at 01:23:48 UTC, sergeiV wrote:
> On Saturday, 5 May 2012 at 23:42:36 UTC, sergeiV wrote:
>> After succesful building of the Derelict libraries using: 'make
>> -flinux.mak DC=dmd', I am unable to compile the provided 
>> example
>> code:
>> http://svn.dsource.org/projects/derelict/branches/Derelict2/doc/index.html
>>
>> They look like linker problems to me.
>>
>> rdmd test.d -Iinclude/Derelict2/import/
>>
>> test.o:(.data+0x10): undefined reference to
>> `_D8derelict6openal2al12__ModuleInfoZ'
>> test.o:(.data+0x18): undefined reference to
>> `_D8derelict6opengl2gl12__ModuleInfoZ'
>> test.o: In function `_Dmain':
>> test.d:(.text._Dmain+0x3d): undefined reference to
>> `_D8derelict6openal2al10DerelictALC8derelict6openal2al16DerelictALLoader'
>> test.d:(.text._Dmain+0x61): undefined reference to
>> `_D8derelict6opengl2gl10DerelictGLC8derelict6opengl2gl16DerelictGLLoader'
>> collect2: ld returned 1 exit status
>> --- errorlevel 1
>>
>> gdc gave an different kind of error:
>> include/Derelict2/import/derelict/util/compat.di:64: Error:
>> identifier 'c_long' is not defined
>>
>> Using a makefile generated errors similar to those for (r)dmd.
>>
>> dmd 2.059
>> derelict2 630
>
> Solved, missed -of:
> rdmd -Iinclude/Derelict2/import/
> -Linclude/Derelict2/lib/libDerelictAL.a
> -Linclude/Derelict2/lib/libDerelictUtil.a -ofderelict_test 
> test.d

This is ofcourse enough:
rdmd -Iinclude/Derelict2/import/ -oftest test.d
(rdmd -Iinclude/Derelict2/import/ test.d FAILS)

Could anybody explain why an output file specification is 
necessary?
Or is this a bug?