Handle Format!()

[muhammad-hassnain]

This is just a dump of my notes to handle this function, so I know where to look at if we decide to support this later.

calling Format!() actually

calls these three

• core::fmt::rt::Argument::<'a>::new_display -> get's called one time for each arg with {} in format
• std::fmt::Arguments::<'a>::new_v1 -> once upper one is done with all, this gets called
• std::fmt::format -> finally, this gets called to actually format the string

I have spent 2 days trying to handle all possible cases here, but I think, there is something else wrong in our assign_constant_value (it's ignoring unrecognized types) it will probably be better to either have a heuristic or a default fall back in those cases. Similarly, in parse_assignment , Rvalue::Aggregate is incomplete, it only caters for the case if operands len is 1, but a slice also ends up here, and a struct can also have multiple arguments, need to look both of these cases.

I have pushed placeholder handler functions for above three, with some notes on what each function is supposed to do in handlers.rs and added an example in examples/crates/safe/io_read1 , this should be classified safe, if we handle this correctly. For now that test case fails.