https://issues.dlang.org/show_bug.cgi?id=24809
Issue ID: 24809
Summary: In some cases, stable sort assigns to unininitialized
elements
Product: D
Version: D2
Hardware: All
OS: All
Status: NEW
Severity: normal
Priority: P1
Component: phobos
Assignee: [email protected]
Reporter: [email protected]
This is essentially an extension of
https://issues.dlang.org/show_bug.cgi?id=24773
The fix for that one partially fixed the problem, but sort has a lot of
branches depending on the types used and the actual set of elements being
sorted, and there's another branch that's much harder to hit which also uses
uninitializedArray in spite of a type defining opAssign (which it will if the
type has a destructor).
The test case that I came up with is
---
void main()
{
static struct E
{
int value;
int valid = 42;
~this()
{
assert(valid == 42);
}
}
import std.array : array;
import std.range : chain, only, repeat;
auto arr = chain(repeat(E(41), 18),
only(E(39)),
repeat(E(41), 16),
only(E(1)),
repeat(E(42), 33),
only(E(33)),
repeat(E(42), 16),
repeat(E(43), 27),
only(E(33)),
repeat(E(43), 34),
only(E(34)),
only(E(43)),
only(E(63)),
repeat(E(44), 42),
only(E(27)),
repeat(E(44), 11),
repeat(E(45), 64),
repeat(E(46), 3),
only(E(11)),
repeat(E(46), 7),
only(E(4)),
repeat(E(46), 34),
only(E(36)),
repeat(E(46), 17),
repeat(E(47), 36),
only(E(39)),
repeat(E(47), 26),
repeat(E(48), 17),
only(E(21)),
repeat(E(48), 5),
only(E(39)),
repeat(E(48), 14),
only(E(58)),
repeat(E(48), 24),
repeat(E(49), 13),
only(E(40)),
repeat(E(49), 38),
only(E(18)),
repeat(E(49), 11),
repeat(E(50), 6)).array();
import std.algorithm.mutation : SwapStrategy;
import std.algorithm.sorting : sort;
arr.sort!((a, b) => a.value < b.value, SwapStrategy.stable)();
}
---
It's not terribly pretty, and there's probably a shorter list of values which
would trigger the problem, but I found it to be quite difficult to purposefully
hit the branch that has the problem, and this list of values does it.
--
