Function interpret_mir 

pub fn interpret_mir<'db>(
    db: &'db (dyn HirDatabase + 'static),
    body: Arc<MirBody<'db>>,
    assert_placeholder_ty_is_unused: bool,
    trait_env: Option<ParamEnvAndCrate<'db>>,
) -> Result<(Result<Const<'db>, MirEvalError<'db>>, MirOutput), MirEvalError<'db>>