gcc/testsuite/gdc.test/runnable/test17373.d

interface Foo { void visit (int); }
interface Bar { void visit(double); }
interface FooBar : Foo, Bar {}
static assert(__traits(getOverloads, FooBar, "visit").length == 2);

interface Fbar { void visit(char); void visit(double); }
interface Triple : Foo, Bar, Fbar {}
static assert(__traits(getOverloads, Triple, "visit").length == 3);

interface InheritanceMadness : FooBar, Triple {}
static assert(__traits(getOverloads, Triple, "visit").length == 3);

interface Simple
{
    int square(int);
    real square(real);
}
static assert(__traits(getOverloads, Simple, "square").length == 2);

void main() {}