gdc --version = gdc (Debian 8.2.0-21) 8.2.0

Multiple symbols when linking derived class with partial override.

File named a.d:

interface A
{
	bool m1();
	bool m2();
}

class AA : A
{
	override bool m1() { return true; }
	override bool m2()
	{
		return true;
	}
}

File named b.d:

import std.stdio;
import a;


class B : AA
{
	override bool m2()
	{
		return true;
	}
}

void main()
{
	auto b = new B;
	writefln("%s",b.m2);
}

Command line :

gdc -c a.d
gdc -c b.d
gdc a.o b.o

/usr/bin/ld: b.o: in function `_DT16_D1a2AA2m1MFZb':
b.d:(.text+0x122): multiple definition of `_DT16_D1a2AA2m1MFZb'; a.o:a.d:(.text+0x71): first defined here

No error if compiled all at once:

gdc a.d b.d