The bug is similar to
https://issues.dlang.org/show_bug.cgi?id=6998. Specifically, here
is the code that can be used to demonstrate it. I'm using GDC
4.9.1 (according to gdc --version).
module badbh;
import std.container, std.string, std.stdio;
class Node {
size_t val;
Node next;
this (size_t val) {
this.val = val;
}
override string toString() {
if (next is null) {
return format("%s", val);
} else {
return format("%s, %s", val, next.toString());
}
}
}
void main () {
//sets up the demo structure
auto n = new Node(40);
n.next = new Node(30);
n.next.next = new Node(10);
n.next.next.next = new Node(20);
writeln(n); //should yield "40, 30, 10, 20"
auto t2 = top2(n);
writeln(n); //watch the segfaults
}
Node[] top2 (Node n) {
auto heap = BinaryHeap!(Array!Node, function bool (Node a, Node
b){return a.val > b.val;})();
Node[] nodes;
auto ptr = n;
while (ptr !is null) {
heap.insert(ptr);
ptr = ptr.next;
}
for (auto i = 0; i < 2; i++) {
nodes ~= heap.front;
heap.removeFront;
}
assert(nodes.length == 2);
//some sanity checks to show my code isn't logically FUBAR
assert(nodes[0] !is null);
assert(nodes[1] !is null);
assert(nodes[0].val == 10);
assert(nodes[1].val == 20);
return nodes;
}
The comments are self-explanatory. This destructive behaviour
occurs *only* when the heap is in a different scope to the
structure - if you were to copy all the code in top2 into main,
the segfault wouldn't happen.
I know that this is definitely a GDC thing - the same code under
DMD works correctly (i.e. prints the whole linked structure and
doesn't segfault).
