feat: derive * for recursive structures

[dj8yfo]

Resolves #7

[dj8yfo]

serde's FindTyParams code isn't perfect.
In commented example it does the right thing.
In a case, which is synonymous:

struct Parametrized<T, V> where T: TraitName {

    field: <T as TraitName>::Associated,
    another: V,     
}

it produces following expansion

impl<T, V> borsh::ser::BorshSerialize for Parametrized<T, V>
where
    T: TraitName,
    T: borsh::ser::BorshSerialize,
    V: borsh::ser::BorshSerialize,
{
...

which is an error

error[E0277]: the trait bound `<T as TraitName>::Associated: BorshSerialize` is not satisfied
  --> src/main.rs:28:10
   |
28 | #[derive(BorshSerialize)]
   |          ^^^^^^^^^^^^^^ the trait `BorshSerialize` is not implemented for `<T as TraitName>::Associated`
   |
   = note: this error originates in the derive macro `BorshSerialize` (in Nightly builds, run with -Z macro-backtrace for more info)
                                                                                                                                                                                                                                                                            
For more information about this error, try `rustc --explain E0277`.

[frol]

This is sic!

P.S. I feel we should have killed borsh-schema earlier, so you would not need to spend so much effort implementing it...

[frol]

I feel this should be the default configuration for the module of even crate, and explicitly opted-out (allowed) whenever necessary. What do you think?

[dj8yfo]

i think that it's so in selene's code (where i borrowed it from) due to convention to specify exact nightly features that are going to be used
(probably because some combinations of them can interact/bug in weird ways, and it's hard to test all possible combinations in nightly; like there's more or less only one stable compiler for a version, and there're infinite number of nightly compilers ) ).
My suggestion, is when feature(non_exhaustive_omitted_patterns_lint) is stabilized, then all of #[cfg_attr(...)] relevant to it can be removed

[dj8yfo]

If the attribute is removed now, then it becomes less apparent, that the feature is not stable yet.

[dj8yfo]

This is sic!

P.S. I feel we should have killed borsh-schema earlier, so you would not need to spend so much effort implementing it...

Well, at least it has some unique quirks, that are more interesting when tried to be implemented than copy-and-paste of functionality from serde )