The following code apparently heap-allocates a closure even though doNothing() takes a scope delegate. This happens when doNothing() is passed a delegate literal. When it's passed the address of a named inner function, no heap allocation takes place.
import core.memory;
void main() {
GC.disable();
foreach(j; 0..1_000_000_000) {
doIt();
}
}
void doIt() {
int i;
doNothing(() { i++; });
}
void doNothing(scope void delegate() dg) {
dg();
}