NSDimension -measurementByConvertingToUnit does not work

[ashalkhakov]

I have this code that works on OSX:

    NSMeasurement *measurement = [[NSMeasurement alloc] initWithDoubleValue:value unit:fromUnit];
    if ([measurement canBeConvertedToUnit:toUnit]) {
        return [measurement measurementByConvertingToUnit:toUnit].doubleValue;
    }

but for GNUstep I have to do instead:

    if ([fromUnit isKindOfClass:[NSDimension class]] && [toUnit isKindOfClass:[NSDimension class]]) {
        NSUnitConverter *fromConv = [(NSDimension *)fromUnit converter];
        NSUnitConverter *toConv   = [(NSDimension *)toUnit converter];
        double baseValue = [fromConv baseUnitValueFromValue:value];
        return [toConv valueFromBaseUnitValue:baseValue];
    }

The code is here. You can comment out the GNUSTEP segment and run XCTest and you'll find that UDUnitConverter fails without the workaround.

I'll probably submit a PR for this, if you think it's worth fixing.