Using DMD 0.110, Windows 98SE.

For some strange reason, for a struct to be used as an AA key, the opEquals and opCmp functions have to be defined with a pointer parameter.  However, when this is done, the comparison operators can no longer be used directly.  For both to work, it is necessary to define two versions of each comparison operator:

----------
struct Qwert {
    char yuiop;

    int opEquals(Qwert* nm) {
        return yuiop == nm.yuiop;
    }

    int opEquals(Qwert nm) {
        return opEquals(&nm);
    }

    int opCmp(Qwert* nm) {
        return yuiop - nm.yuiop;
    }

    int opCmp(Qwert nm) {
        return opCmp(&nm);
    }
}


void main() {
    int[Qwert] qaz;

    Qwert asdfg, hjkl, zxcvb;

    asdfg.yuiop = hjkl.yuiop = 42;
    zxcvb.yuiop = 69;

    assert(asdfg == hjkl);
    assert(asdfg != zxcvb);
    assert(hjkl < zxcvb);

    qaz[asdfg] = 20;
    assert (qaz[asdfg] == 20);
}
----------

If I get rid of opEquals(Qwert) and opCmp(Qwert), then needless to say, I get

D:\My Documents\Programming\D\Tests\bugs\struct_equals.d(30): function struct_equals.Qwert.opEquals (Qwert *q) does not match argument types (Qwert )
D:\My Documents\Programming\D\Tests\bugs\struct_equals.d(30): cannot implicitly convert expression hjkl of type Qwert to Qwert *

and similarly with the next two asserts.  OTOH, if I only define opEquals(Qwert) and opCmp(Qwert), then

D:\My Documents\Programming\D\Tests\bugs\struct_equals.d(4): function struct_equals.Qwert.opEquals must be declared as extern (D) int opEquals(Qwert*)
D:\My Documents\Programming\D\Tests\bugs\struct_equals.d(12): function struct_equals.Qwert.opCmp must be declared as extern (D) int opCmp(Qwert*)

Having to define both opEquals(Qwert) and opEquals(Qwert*) (and similarly with opCmp) seems an arbitrary requirement.  Surely you should only have to define one?  And surely someone who designs a struct shouldn't have to explicitly make it usable as an AA key?

Stewart.

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