Drop (empty) unused structs

[franziskuskiefer]

Eurydice shouldn't produce empty structs, especially when they are not actually used.
In Rust we sometimes need structs to attach functions while they don't actually do anything.
While the generated code is correct, the struct in the following example should not be generated (dropped).

struct MyStruct {}

trait Fun {
    fn f() -> u8;
}

impl Fun for MyStruct {
    fn f() -> u8 {
        5
    }
}

fn generic_fun<F: Fun>() -> u8 {
    F::f()
}

The following struct won't compile (in most cases) and is not needed.

typedef struct eurydice_tests_MyStruct_s {  } eurydice_tests_MyStruct;

[msprotz]

What behavior would you like? I can probably rather easily replace the struct with a unit, which would then allow unused parameter elimination, etc.

[franziskuskiefer]

I want compiling C code 😉 So I think it's either a unit as you suggest, or treating them specially to drop them. I actually thought that the phase that removes unused code would also cover structs. But maybe it doesn't?
But a unit sounds reasonable and should work.