[neonsunset]

Structs in C# or F# are not low-level per se, they simply are a choice and used frequently in gamedev. So is stackalloc because using it is just 'var things = (stackalloc Thing[5])' where the type of `things` is Span<Thing>. The keyword is a bit niche but it's very normal to see it in code that cares about avoiding allocations.

Note that going more hands-on with these is not the same as violating memory safety - C# even has ref and byreflike struct lifetime analysis specifically to ensure this not an issue (https://em-tg.github.io/csborrow/).

[yyyk]

Right, it depends on how far one wants to go to avoid allocations. structs and spans are safe. But one can go even deeper and pin pointers and do Unsafe.AsPointer and get a de-facto (unsafe) union out of it....

>https://em-tg.github.io/csborrow/

Oooh... I didn't know scoped refs existed.

[int_19h]

If you want an unsafe union, that's what StructLayout.Explicit and FieldOffset is for - a struct with all fields placed at offset 0 is exactly the same as a C union.