Specifying @nogc on structs seems to have no effect

[Mike Parker]

On Tuesday, 19 September 2017 at 14:22:21 UTC, Craig Black wrote:

> Thank you for your response.  The @nogc attribute is good, but 
> in my opinion it is incomplete if all types still require 
> scanning.  The purpose of not employing GC in certain sections 
> of code is performance, and we are sacrificing performance with 
> every allocation unit that is needlessly scanned.
>
> -Craig

As I wrote in my previous post, *no* GC activity will happen 
inside a @nogc function. The only time any scanning or 
collections can take place is when a allocation is requested. If 
none are requested, there's no activity.

Aside from that, there are other options. If you don't want your 
Foo member variable to be scanned, then allocate it outside the 
GC heap (see Mallocator in std.allocator). You can call 
GC.disable whenever you want (but be wary of the impact 
performance when you later call GC.collect). You can allocate 
outside of your hot loops and use stack allocation where possible.

I suggest you take a look at the ongoing GC series on the D Blog. 
The next post (coming later this week) covers heap allocations.

https://dlang.org/blog/the-gc-series/