Can the D compiler detect final and optimize?

[IGotD-]

On Friday, 13 March 2020 at 15:15:50 UTC, rikki cattermole wrote:
> Why would this be needed?
>
> With ldc -O3 the test function can be completely erased:
>
> import std;
> void main()
> {
>     Foo foo = new Foo;
>     foo.x = 7;
>     test(foo);
> }
>
> void test(Foo foo) {
>     writeln(foo.get);
> }
>
> class Foo {
>     int x;
>
>     int get() { return x; }
> }

The D programming language by Andrei Alexandrescu. Chapter 6.6.

"So final non-override methods are never subjected to indrect 
calls; instead they enjoy the same calling convention, low 
overhead and inlining opportunities as regular functions"

I think I saw a difference between DMD and LDC previously where 
LDC actually could in some cases infer that the method is final.

If the compiler can infer that a method is final (officially by 
language standard), then what would the argument for final as 
default be?