Unable to serialize or deserialize

[lightclient]

I'm trying to deserialize params that look like this:

["0x0000000000000000000000000000000000000000"]

using the following struct:

#[derive(Deserialize_tuple)]
 struct BalanceParams {
     address: Address,
}

but I get these errors:

error[E0658]: The attribute `serde` is currently unknown to the compiler and may have meaning added to it in the future (see issue #29642)
  --> src/lib.rs:20:10
   |
20 | #[derive(Deserialize_tuple)]
   |          ^^^^^^^^^^^^^^^^^

error[E0433]: failed to resolve: use of undeclared type or module `serde_derive`
  --> src/lib.rs:20:10
   |
20 | #[derive(Deserialize_tuple)]
   |          ^^^^^^^^^^^^^^^^^ use of undeclared type or module `serde_derive`

error[E0277]: the trait bound `<BalanceParams as serde::de::Deserialize<'de>>::deserialize::Inner: serde::de::Deserialize<'_>` is not satisfied
  --> src/lib.rs:20:10
   |
20 | #[derive(Deserialize_tuple)]
   |          ^^^^^^^^^^^^^^^^^ the trait `serde::de::Deserialize<'_>` is not implemented for `<BalanceParams as serde::de::Deserialize<'de>>::deserialize::Inner`
   |

Even if I use serde (which I don't think I should need to?), the issues remain.

[lightclient]

If I swap the Address type for i32, I still see the same issue.

[kardeiz]

@c-o-l-o-r thanks for the issue. I have released a new version 0.2.3 that should resolve the issue.

Previously, this crate did not depend on serde or serde_derive since it doesn't really depend on those crates; it just expands to code in your program, with the assumption that you would bring your own serde and serde_derive.

However, I don't think there is any downside for this crate to depend on serde/serde_derive directly, so I have now done so.

I'm closing this, but please let me know if 0.2.3 doesn't resolve your issue.

[lightclient]

Thanks for the quick response! I've updated 0.2.3, but now I'm seeing the following error:

thread 'rustc' has overflowed its stack
fatal runtime error: stack overflow

Maybe 128 is too low?

serde_tuple/src/lib.rs

Line 20 in 5c91851

#![recursion_limit = "128"]

[kardeiz]

@c-o-l-o-r can you confirm that it is this proc-macro that is causing the stack overflow?

For example, if you put:

#![recursion_limit = "4096"] 

At the top of your main.rs/lib.rs, does it still crash?

If so, I will increate the recursion limit here to 4096 and cut a new version.

[lightclient]

@kardeiz, yes if I put #![recursion_limit = "4096"] in my lib.rs it still crashes. 😢

[kardeiz]

Okay, 0.2.4 has it increased to 4096.

If that doesn't work, I'll need to do some research into the implications of very large recursion limits, or see if there is anything I can do here to avoid running into this...

[lightclient]

Hmm, it looks like the issue persists. I even cloned this repo and raised the limit to a crazy number. I've been compiling this using the stable channel, but I gave it a shot using nightly and got this:

error: suffixes on a tuple index are invalid
  --> src/lib.rs:20:10
   |
20 | #[derive(Deserialize_tuple)]
   |          ^^^^^^^^^^^^^^^^^ invalid suffix `usize`

error: proc-macro derive produced unparseable tokens
  --> src/lib.rs:20:10
   |
20 | #[derive(Deserialize_tuple)]
   |          ^^^^^^^^^^^^^^^^^

[kardeiz]

@c-o-l-o-r Your issue on nightly is related to this: rust-lang/rust#59418. It looks like the error is going to be rolled back to a warning tonight (or was last night?; rust-lang/rust#60210). I went ahead and fixed this in 0.2.5.

Can you share your code for Address (and any related de/serialized structs) so I can test the recursion issue?

[lightclient]

It doesn't seem like the issue is related to the Address type (although you can find its definition here). I've put together a minimal repo demonstrating my issue. Honestly, it may just be "user error". 😅

https://github.com/c-o-l-o-r/serde_tuple_issue

[kardeiz]

Aha! I encountered this exact issue a couple months ago: serde-rs/serde#1467.

According to dtolnay, this is a compiler bug: rust-lang/rust#55779.

I don't really understand all the issues around the bug report, but for a quick fix you can put:

#[derive(serde_derive::Deserialize)]
struct Empty {}

somewhere in your code to make the SO go away. Or if you have any other structs that #[derive(Deserialize), that should work as well.

[lightclient]

Fascinating! Thank you @kardeiz!