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On Sunday, 14 January 2024 at 15:40:22 UTC, Richard (Rikki) Andrew Cattermole wrote:
>I think that you might have this slightly backwards, but please do clarify.
Sorry, I've reread entire thread, and it seems my suggestion is not related to what you've proposed with @localnogc, it is related to another problem with delegate callbacks, where you need to mark them @nogc to be called in @nogc function.
So to make things clear about what I suggested:
void perform() {
acceptDelegateWithGc(() {
Object obj = new Object();
return obj;
});
acceptNoGcDelegatesOnly(() {
Object obj = new Object();
return obj;
}); // This fails since only nogc delegates are allowed
acceptNoGcDelegatesOnly(() @trustedgc {
Object obj = new Object();
return obj;
}); // This will work since delegate is marked with trustedgc, and therefore user knows whats he's doing when a nogc function calls a method that uses gc.
}
void acceptDelegateWithGc(Object delegate() @trustedgc create) @nogc {
create();
}
void acceptNoGcDelegatesOnly(Object delegate() @nogc create) @nogc {
create();
}
In your hot path case, @trustedgc functionality might be used, if it was possible to put it on statement level like this:
void hot(float[] a, float b) @nogc {
size_t last;
float delegate() dg = () { // error: will allocate closure context with GC
if (last > a.length)
return float.init;
return a[last++] + b;
};
@trustedgc accept(dg); // ok, accept uses GC, this call is not checked.
}
This example is similar to a topic that was ongoing about @trusted statement blocks, which I hope would be revisited in future and implemented.
Best regards,
Alexandru.
