SerdeAnyMap: add unsafe_stable_anymap feature that uses type_name instead of TypeId::of

[domenukk]

While technically unsound, this just might give us a build-agnostic anymap which would pre pretty nice to have to store and load state.

/edit: fixes #1374

[domenukk]

@addisoncrump just how stupid of an idea is this?

[addisoncrump]

Since we already require 'static, it's actually safe afaik. That said, it will be significantly more expensive to compute since we end up hashing what could be a very long name to enter the item into the hashmap.

[addisoncrump]

Ah, actually, it theoretically could be problematic if the type names (not including the crate path) are exactly the same, but I'm quite certain this won't happen in practice.

[domenukk]

If they are all 'static we could also &'static str directly? That sounds faster to compare in the best case?

[domenukk]

Sad, doesn't seem to work:

error: lifetime may not live long enough
   --> libafl_bolts/src/serdeany.rs:143:21
    |
132 |     impl<'de> serde::de::Visitor<'de> for BoxDynVisitor {
    |          --- lifetime `'de` defined here
...
143 |             let id: TypeRepr = visitor.next_element()?.unwrap();
    |                     ^^^^^^^^ type annotation requires that `'de` must outlive `'static`

error: lifetime may not live long enough
   --> libafl_bolts/src/serdeany.rs:227:9
    |
225 |     #[derive(Debug, Serialize, Deserialize)]
    |                                ----------- lifetime `'de` defined here
226 |     pub struct SerdeAnyMap {
227 |         map: HashMap<TypeRepr, Box<dyn SerdeAny>>,
    |         ^^^ requires that `'de` must outlive `'static`

error: lifetime may not live long enough
   --> libafl_bolts/src/serdeany.rs:424:9
    |
422 |     #[derive(Debug, Serialize, Deserialize)]
    |                                ----------- lifetime `'de` defined here
423 |     pub struct NamedSerdeAnyMap {
424 |         map: HashMap<TypeRepr, HashMap<u64, Box<dyn crate::serdeany::SerdeAny>>>,
    |         ^^^ requires that `'de` must outlive `'static`

[addisoncrump]

We can manually impl Deserialize here.

[addisoncrump]

If they are all 'static we could also &'static str directly? That sounds faster to compare in the best case?

Static lifetime means that, if I own the value, it will live for as long as I hold it. It doesn't guarantee that these values will be in the same place between executions, so we can't serialize them as &'static str. Instead, we'll need to manually deserialise to match the entries in the local registry.

[addisoncrump]

Actually, we can do a sneaky and impl Deserialize for a wrapper type around the TypeRepr to simplify this.

[domenukk]

Do you want to give it a shot?

[addisoncrump]

Sure, I'll take a crack at it now.

[addisoncrump]

Can you commit the non-working code? I'll fix it from there.

[domenukk]

I just replaced String with &'static str as TypeRepr

[domenukk]

@addisoncrump I'm not 100% sure if this type annotation is correct (or should be borrowed or something?)

[domenukk]

@addisoncrump just open a new PR if you manage to do it with 'static str somehow