Stack frames larger than 4K should be rejected, but what if I want more

[Dennis]

On Sunday, 27 June 2021 at 20:17:48 UTC, Dennis wrote:
> I think it's only meant to apply to @safe functions, not 
> @system or @trusted ones.

Actually, that's hard to realize, since the check for `@safe` is 
a semantic check in the frontend, while final stack sizes are 
only known by the backend. Making the frontend guess an upper 
bound is hard because of tail calls and/or inlining, e.g:

```D
void f(ubyte[] x) {
     ubyte[4000] bufA = void;
     g(bufA[]);
}

void g(ubyte[] bufA) {
     ubyte[4000] bufB = void;
     h(bufA, bufB);
}

void h(ubyte[] x, ubyte[] y);
```
With ldc -O3, the stack frame of `f` is 8008 bytes because it has 
`g` inlined.