Weird behaviour when adding jwt-simple to my project

[l1x]

❯ cargo lambda build --release --arm64
   Compiling radmin v0.1.0 (/Users/l1x/code/datadeft/datadeft/backend/radmin)
    Finished release [optimized] target(s) in 8.68s

❯ git diff Cargo.toml
diff --git a/backend/radmin/Cargo.toml b/backend/radmin/Cargo.toml
index f1b5c84..400457c 100644
--- a/backend/radmin/Cargo.toml
+++ b/backend/radmin/Cargo.toml
@@ -8,6 +8,7 @@ async_once = "0.2.6"
 aws-config = "0.51.0"
 aws-sdk-s3 = "0.21.0"
 chrono = "0.4.23"
+jwt-simple = "0.11.2"
 lambda_http = {version = "0.7.1", optional = true}
 lambda_runtime = {version = "0.7.1", optional = true}
 lazy_static = "1.4.0"

❯ cargo lambda build --release --arm64
   Compiling radmin v0.1.0 (/Users/l1x/code/datadeft/datadeft/backend/radmin)
error[E0277]: `*const aws_sdk_s3::Client` cannot be sent between threads safely
  --> src/radmin.rs:23:1
   |
23 | / lazy_static! {
24 | |     static ref S3_CLIENT: AsyncOnce<S3Client> = AsyncOnce::new(async {
25 | |         let region_provider = RegionProviderChain::default_provider().or_else("eu-west-1");
26 | |         let config = aws_config::from_env().region(region_provider).load().await;
...  |
52 | |     };
53 | | }
   | |_^ `*const aws_sdk_s3::Client` cannot be sent between threads safely
   |
   = help: the trait `Send` is not implemented for `*const aws_sdk_s3::Client`
   = note: required for `Cell<*const aws_sdk_s3::Client>` to implement `Send`
   = note: required because it appears within the type `AsyncOnce<aws_sdk_s3::Client>`
   = note: required for `spin::once::Once<AsyncOnce<aws_sdk_s3::Client>>` to implement `Sync`
   = note: required because it appears within the type `Lazy<AsyncOnce<aws_sdk_s3::Client>>`
   = note: shared static variables must have a type that implements `Sync`
   = note: this error originates in the macro `__lazy_static_create` which comes from the expansion of the macro `lazy_static` (in Nightly builds, run with -Z macro-backtrace for more info)

[jedisct1]

That seems off-topic.

But usually, in order to work around this error, you need to wrap everything in std::sync::Arc<>, and if that doesn't work, try std::sync::Arc<std::sync::Mutex<>>. If that still doesn't work, make all your structures Clone-able.

[nickpresta]

For what it's worth, I'm seeing something similar. The act of simply including jwt-simple to my Cargo.toml causes my build to fail (in this case, another crate is failing):

187 | /     lazy_static!{
188 | |         static ref _shared_context_cache: Arc<PredictionContextCache> = Arc::new(PredictionContextCache::new());
189 | |         static ref VOCABULARY: Box<dyn Vocabulary> = Box::new(VocabularyImpl::new(_LITERAL_NAMES.iter(), _SYMBOLIC_NAMES.iter(), None));
190 | |     }
    | |_____^ `(dyn Vocabulary + 'static)` cannot be sent between threads safely
    |
    = help: the trait `Send` is not implemented for `(dyn Vocabulary + 'static)`
    = note: required for `Unique<(dyn Vocabulary + 'static)>` to implement `Send`
    = note: required because it appears within the type `Box<(dyn Vocabulary + 'static)>`
    = note: required for `spin::once::Once<Box<(dyn Vocabulary + 'static)>>` to implement `Sync`
    = note: required because it appears within the type `Lazy<Box<(dyn Vocabulary + 'static)>>`
    = note: shared static variables must have a type that implements `Sync`
    = note: this error originates in the macro `__lazy_static_create` which comes from the expansion of the macro `lazy_static` (in Nightly builds, run with -Z macro-backtrace for more info)

After doing some digging, this actually looks to be an issue with lazy_static:

rust-lang-nursery/lazy-static.rs#204

Specifically, the rsa crate that's included by jwt-simple depends on num-bigint-dig, which depends on lazy_static with the spin_no_std feature, and once that feature is enabled everyone gets it. Here's a related issue: rust-lang-nursery/lazy-static.rs#150

At the end of the day, I ended up forking num-bigint-dig and then patching it in my Cargo.toml:

[patch.crates-io]
num-bigint-dig = { git = "https://github.com/nickpresta/num-bigint.git", branch = "master" }

This now gets the cargo build working again.