On Monday, 4 April 2016 at 03:28:01 UTC, Yuxuan Shui wrote:
I have encountered a weird bug.
I defined a Set class, which has a opBinary!"-". And somehow
this:
auto tmp = set_a-set_b;
produces different results as this:
set_a = set_a-set_b;
the latter will produce an empty set.
I tried to reduce the source code to get a test case. But this
problem just goes away after removing some code.
Any ideas what I could have done wrong?
OK, I think I got a test case:
import std.traits;
struct Set {
public:
void insert(ulong v) {
aa[v] = true;
}
size_t size() const {
return aa.length;
}
auto opBinary(string op)(ref Set o) const {
Set ret;
foreach(k; aa.byKey)
if (k !in o.aa)
ret.insert(k);
return ret;
}
@disable this(this);
bool[ulong] aa;
}
struct XX {
Set a, b, tmp;
this(int n) {
a.insert(n);
tmp = a-b;
a = a-b;
}
}
void main(){
import std.stdio;
XX xx = XX(1000);
writeln(xx.a.size);
writeln(xx.tmp.size);
}
This does not happen when 'a' is on stack, that's why I was
having trouble reproducing it.
I don't think this is valid code, because Set has disabled
post-blit, 'a = a-b' should report an error. However, I don't
think current behavior of dmd is correct either.
