isQualifierConvertible

// Mutable and immmutable both convert to const...
static assert( isQualifierConvertible!(char, const(char)));
static assert( isQualifierConvertible!(immutable(char), const(char)));
// ...but const does not convert back to mutable or immutable
static assert(!isQualifierConvertible!(const(char), char));
static assert(!isQualifierConvertible!(const(char), immutable(char)));