On Wednesday, 17 February 2021 at 19:42:00 UTC, tsbockman wrote:
On Wednesday, 17 February 2021 at 17:45:01 UTC, H. S. Teoh
wrote:
I.e., the following is NOT a good idea:
struct S {
void delegate() member;
this() {
member = &this.impl;
}
private void impl();
}
because a pointer to S is stored inside S itself, so as soon
as S gets copied or moved, the delegate context pointer is no
longer valid (or else points to a different copy of the struct
than the one it will be called from).
A copy constructor and opAssign can be used to update pointers
that are relative to &this:
https://dlang.org/spec/struct.html#struct-copy-constructor
Unfortunately this is not enough, because the compiler is free to
implicitly move struct instances in memory any time it wants to.
See the bug report below for more details:
https://issues.dlang.org/show_bug.cgi?id=17448
Until D gets move constructors, structs with interior pointers
should be avoided.
