lifetimes aren't fully supported

[1xX69]

#[axum_codec::apply(encode, decode)]
pub struct HelpLink<'a> {
    pub description: &'a str,
}

#[axum_codec::apply(encode, decode)]
pub enum ErrorDetail<'a> {
    Help { links: Vec<HelpLink<'a>> },
}

fn main() {}

➜  monorepo git:(master) ✗ cargo build -p sample
   Compiling serde v1.0.217
   Compiling axum-core v0.5.0
   Compiling thiserror v1.0.69
   Compiling serde_json v1.0.138
   Compiling axum v0.8.1
   Compiling axum-codec v0.0.19
   Compiling sample v0.1.0 (/home/user/workspace/monorepo/sample)
error: lifetime may not live long enough
 --> sample/src/main.rs:8:12
  |
6 | #[axum_codec::apply(encode, decode)]
  | ------------------------------------ lifetime `'de` defined here
7 | pub enum ErrorDetail<'a> {
  |                      -- lifetime `'a` defined here
8 |     Help { links: Vec<HelpLink<'a>> },
  |            ^^^^^^^^^^^^^^^^^^^^^^^^ requires that `'de` must outlive `'a`
  |
  = help: consider adding the following bound: `'de: 'a`

error: could not compile `sample` (bin "sample") due to 2 previous errors

[1xX69]

Whoops, my bad! It actually works, you just need to add #[serde(borrow)]

like this:

#[axum_codec::apply(encode, decode)]
pub struct HelpLink<'a> {
    pub description: &'a str,
}

#[axum_codec::apply(encode, decode)]
pub enum ErrorDetail<'a> {
    Help {
        #[serde(borrow)]
        links: Vec<HelpLink<'a>>,
    },
}

[1xX69]

But if I try to add more variants:

#[axum_codec::apply(encode, decode)]
pub struct HelpLink<'a> {
    pub description: &'a str,
}

/// Enum representing different types of error details.
#[axum_codec::apply(encode, decode)]
pub enum ErrorDetail<'a> {
    Help {
        #[serde(borrow)]
        links: Vec<HelpLink<'a>>,
    },

    LocalizedMessage {
        message: &'a str,
    },
}

I get an internal compiler error:

$ cargo build -p sample
   Compiling sample v0.1.0 (/home/user/workspace/monorepo/sample)
error: internal compiler error: encountered incremental compilation error with evaluate_obligation(f504fce775bc4b43-bf7636c59bb396fa)
  |
  = help: This is a known issue with the compiler. Run `cargo clean -p sample` or `cargo clean` to allow your project to compile
  = note: Please follow the instructions below to create a bug report with the provided information
  = note: See <https://github.com/rust-lang/rust/issues/84970> for more information


thread 'rustc' panicked at /rustc/f280acf4c743806abbbbcfe65050ac52ec4bdec0/compiler/rustc_query_system/src/query/plumbing.rs:731:9:
Found unstable fingerprints for evaluate_obligation(f504fce775bc4b43-bf7636c59bb396fa): Ok(EvaluatedToOk)
stack backtrace:
   0:     0x7ef031998c64 - <std::sys::backtrace::BacktraceLock::print::DisplayBacktrace as core::fmt::Display>::fmt::h8d9b2abef2510cd1
   1:     0x7ef03221a2ac - core::fmt::write::heb9cf6889f45a11e
   2:     0x7ef033184ed1 - std::io::Write::write_fmt::h6360a21e44de67e4
   3:     0x7ef031998ac2 - std::sys::backtrace::BacktraceLock::print::h9319588d0d6e4878
   4:     0x7ef03199b2ce - std::panicking::default_hook::{{closure}}::h4c968bafc99c0b41
   5:     0x7ef03199aea4 - std::panicking::default_hook::hafb4ab1b4e12432b
   6:     0x7ef030ae86e7 - std[54256809445ede48]::panicking::update_hook::<alloc[4946864fce885641]::boxed::Box<rustc_driver_impl[f8acc18714ba66d9]::install_ice_hook::{closure#1}>>::{closure#0}
   7:     0x7ef03199bb43 - std::panicking::rust_panic_with_hook::h5b5ba4a5cbdd9043
   8:     0x7ef03199b83a - std::panicking::begin_panic_handler::{{closure}}::h761c7933b6bd63bc
   9:     0x7ef031999139 - std::sys::backtrace::__rust_end_short_backtrace::hf28ea39c64a8ec49
  10:     0x7ef03199b4fd - rust_begin_unwind
  11:     0x7ef02e646e60 - core::panicking::panic_fmt::hbb352f67f9fc2f03
  12:     0x7ef0310832d3 - rustc_query_system[63b8370bb4899dc2]::query::plumbing::incremental_verify_ich_failed::<rustc_middle[fa8070f18412b0da]::ty::context::TyCtxt>
  13:     0x7ef0326ffc58 - rustc_query_system[63b8370bb4899dc2]::query::plumbing::try_execute_query::<rustc_query_impl[1e0edd06af9652a1]::DynamicConfig<rustc_query_system[63b8370bb4899dc2]::query::caches::DefaultCache<rustc_type_ir[f32108c434f59f4e]::canonical::CanonicalQueryInput<rustc_middle[fa8070f18412b0da]::ty::context::TyCtxt, rustc_middle[fa8070f18412b0da]::ty::ParamEnvAnd<rustc_middle[fa8070f18412b0da]::ty::predicate::Predicate>>, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 2usize]>>, false, false, false>, rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt, true>
  14:     0x7ef03270fd85 - rustc_query_impl[1e0edd06af9652a1]::query_impl::evaluate_obligation::get_query_incr::__rust_end_short_backtrace
  15:     0x7ef032baaeae - <rustc_trait_selection[d035bd7351711dff]::traits::fulfill::FulfillProcessor as rustc_data_structures[30a19619986f318]::obligation_forest::ObligationProcessor>::process_obligation
  16:     0x7ef03220f17f - <rustc_data_structures[30a19619986f318]::obligation_forest::ObligationForest<rustc_trait_selection[d035bd7351711dff]::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection[d035bd7351711dff]::traits::fulfill::FulfillProcessor>
  17:     0x7ef032650347 - <rustc_trait_selection[d035bd7351711dff]::traits::fulfill::FulfillmentContext<rustc_trait_selection[d035bd7351711dff]::traits::FulfillmentError> as rustc_infer[1161895a0fa9626d]::traits::engine::TraitEngine<rustc_trait_selection[d035bd7351711dff]::traits::FulfillmentError>>::select_all_or_error
  18:     0x7ef032ad2bce - rustc_hir_analysis[200ebf77cfece739]::check::compare_impl_item::check_type_bounds
  19:     0x7ef032ac82bc - rustc_hir_analysis[200ebf77cfece739]::check::compare_impl_item::compare_impl_item
  20:     0x7ef032ac64b7 - rustc_query_impl[1e0edd06af9652a1]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[1e0edd06af9652a1]::query_impl::compare_impl_item::dynamic_query::{closure#2}::{closure#0}, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 1usize]>>
  21:     0x7ef03270d2aa - rustc_query_system[63b8370bb4899dc2]::query::plumbing::try_execute_query::<rustc_query_impl[1e0edd06af9652a1]::DynamicConfig<rustc_data_structures[30a19619986f318]::vec_cache::VecCache<rustc_span[a6bcc981ad5e83db]::def_id::LocalDefId, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[63b8370bb4899dc2]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt, true>
  22:     0x7ef03270f4f6 - rustc_query_impl[1e0edd06af9652a1]::query_impl::compare_impl_item::get_query_incr::__rust_end_short_backtrace
  23:     0x7ef02f991f83 - rustc_hir_analysis[200ebf77cfece739]::check::check::check_item_type
  24:     0x7ef02f9684fb - rustc_hir_analysis[200ebf77cfece739]::check::wfcheck::check_well_formed
  25:     0x7ef032c762b7 - rustc_query_impl[1e0edd06af9652a1]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[1e0edd06af9652a1]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 1usize]>>
  26:     0x7ef03270d661 - rustc_query_system[63b8370bb4899dc2]::query::plumbing::try_execute_query::<rustc_query_impl[1e0edd06af9652a1]::DynamicConfig<rustc_data_structures[30a19619986f318]::vec_cache::VecCache<rustc_span[a6bcc981ad5e83db]::def_id::LocalDefId, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[63b8370bb4899dc2]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt, true>
  27:     0x7ef0331f1954 - rustc_query_impl[1e0edd06af9652a1]::plumbing::force_from_dep_node::<rustc_query_impl[1e0edd06af9652a1]::DynamicConfig<rustc_data_structures[30a19619986f318]::vec_cache::VecCache<rustc_span[a6bcc981ad5e83db]::def_id::LocalDefId, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[63b8370bb4899dc2]::dep_graph::graph::DepNodeIndex>, false, false, false>>
  28:     0x7ef0331f17ad - <rustc_query_impl[1e0edd06af9652a1]::plumbing::query_callback<rustc_query_impl[1e0edd06af9652a1]::query_impl::check_well_formed::QueryType>::{closure#0} as core[c7a133740aa39aee]::ops::function::FnOnce<(rustc_middle[fa8070f18412b0da]::ty::context::TyCtxt, rustc_query_system[63b8370bb4899dc2]::dep_graph::dep_node::DepNode)>>::call_once
  29:     0x7ef03221fa7f - <rustc_query_system[63b8370bb4899dc2]::dep_graph::graph::DepGraphData<rustc_middle[fa8070f18412b0da]::dep_graph::DepsType>>::try_mark_previous_green::<rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt>
  30:     0x7ef03221f1ae - <rustc_query_system[63b8370bb4899dc2]::dep_graph::graph::DepGraphData<rustc_middle[fa8070f18412b0da]::dep_graph::DepsType>>::try_mark_green::<rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt>
  31:     0x7ef032cf317d - rustc_query_system[63b8370bb4899dc2]::query::plumbing::ensure_must_run::<rustc_query_impl[1e0edd06af9652a1]::DynamicConfig<rustc_query_system[63b8370bb4899dc2]::query::caches::DefaultCache<rustc_span[a6bcc981ad5e83db]::def_id::LocalModDefId, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt>
  32:     0x7ef03312c993 - rustc_query_impl[1e0edd06af9652a1]::query_impl::check_mod_type_wf::get_query_incr::__rust_end_short_backtrace
  33:     0x7ef0325c5b4d - rustc_hir_analysis[200ebf77cfece739]::check_crate
  34:     0x7ef0325cfc5c - rustc_interface[3b74b9441e612cca]::passes::run_required_analyses
  35:     0x7ef033180e7a - rustc_interface[3b74b9441e612cca]::passes::analysis
  36:     0x7ef033180e59 - rustc_query_impl[1e0edd06af9652a1]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[1e0edd06af9652a1]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 0usize]>>
  37:     0x7ef03317c759 - rustc_query_system[63b8370bb4899dc2]::query::plumbing::try_execute_query::<rustc_query_impl[1e0edd06af9652a1]::DynamicConfig<rustc_query_system[63b8370bb4899dc2]::query::caches::SingleCache<rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt, true>
  38:     0x7ef03317c162 - rustc_query_impl[1e0edd06af9652a1]::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
  39:     0x7ef03328923c - rustc_interface[3b74b9441e612cca]::passes::create_and_enter_global_ctxt::<core[c7a133740aa39aee]::option::Option<rustc_interface[3b74b9441e612cca]::queries::Linker>, rustc_driver_impl[f8acc18714ba66d9]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  40:     0x7ef03327caeb - rustc_interface[3b74b9441e612cca]::interface::run_compiler::<(), rustc_driver_impl[f8acc18714ba66d9]::run_compiler::{closure#0}>::{closure#1}
  41:     0x7ef033107550 - std[54256809445ede48]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[3b74b9441e612cca]::util::run_in_thread_with_globals<rustc_interface[3b74b9441e612cca]::util::run_in_thread_pool_with_globals<rustc_interface[3b74b9441e612cca]::interface::run_compiler<(), rustc_driver_impl[f8acc18714ba66d9]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  42:     0x7ef033107974 - <<std[54256809445ede48]::thread::Builder>::spawn_unchecked_<rustc_interface[3b74b9441e612cca]::util::run_in_thread_with_globals<rustc_interface[3b74b9441e612cca]::util::run_in_thread_pool_with_globals<rustc_interface[3b74b9441e612cca]::interface::run_compiler<(), rustc_driver_impl[f8acc18714ba66d9]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[c7a133740aa39aee]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  43:     0x7ef03310832f - std::sys::pal::unix::thread::Thread::new::thread_start::h208202f9d25af663
  44:     0x7ef02d297d02 - start_thread
  45:     0x7ef02d3173ac - __GI___clone3
  46:                0x0 - <unknown>

error: the compiler unexpectedly panicked. this is a bug.

note: we would appreciate a bug report: https://github.com/rust-lang/rust/issues/new?labels=C-bug%2C+I-ICE%2C+T-compiler&template=ice.md

note: please make sure that you have updated to the latest nightly

note: please attach the file at `/home/user/workspace/monorepo/rustc-ice-2025-02-28T08_39_15-206461.txt` to your bug report

note: compiler flags: --crate-type lib -C embed-bitcode=no -C debuginfo=2 -C incremental=[REDACTED]

note: some of the compiler flags provided by cargo are hidden

query stack during panic:
#0 [evaluate_obligation] evaluating trait selection obligation `_::HelpLinkEncoder: core::marker::Sync`  |  = note: this failure-note originates in the derive macro `axum_codec::__private::bitcode::Encode` (in Nightly builds, run with -Z macro-backtrace for more info)

#1 [compare_impl_item] checking assoc item `_::<impl at sample/src/lib.rs:7:1: 7:37>::Encoder` is compatible with trait definition
... and 2 other queries... use `env RUST_BACKTRACE=1` to see the full query stack
there was a panic while trying to force a dep node
try_mark_green dep node stack:
#0 check_mod_type_wf(sample[d599])
end of try_mark_green dep node stack
error: could not compile `sample` (lib) due to 1 previous error

$ cat /home/user/workspace/monorepo/rustc-ice-2025-02-28T08_39_15-206461.txt
thread 'rustc' panicked at /rustc/f280acf4c743806abbbbcfe65050ac52ec4bdec0/compiler/rustc_query_system/src/query/plumbing.rs:731:9:
Found unstable fingerprints for evaluate_obligation(f504fce775bc4b43-bf7636c59bb396fa): Ok(EvaluatedToOk)
stack backtrace:
   0:     0x7ef0335b0771 - std::backtrace::Backtrace::create::h0975e4261c850498
   1:     0x7ef0319834d5 - std::backtrace::Backtrace::force_capture::hdd554246d802e7f4
   2:     0x7ef030ae8e31 - std[54256809445ede48]::panicking::update_hook::<alloc[4946864fce885641]::boxed::Box<rustc_driver_impl[f8acc18714ba66d9]::install_ice_hook::{closure#1}>>::{closure#0}
   3:     0x7ef03199bb43 - std::panicking::rust_panic_with_hook::h5b5ba4a5cbdd9043
   4:     0x7ef03199b83a - std::panicking::begin_panic_handler::{{closure}}::h761c7933b6bd63bc
   5:     0x7ef031999139 - std::sys::backtrace::__rust_end_short_backtrace::hf28ea39c64a8ec49
   6:     0x7ef03199b4fd - rust_begin_unwind
   7:     0x7ef02e646e60 - core::panicking::panic_fmt::hbb352f67f9fc2f03
   8:     0x7ef0310832d3 - rustc_query_system[63b8370bb4899dc2]::query::plumbing::incremental_verify_ich_failed::<rustc_middle[fa8070f18412b0da]::ty::context::TyCtxt>
   9:     0x7ef0326ffc58 - rustc_query_system[63b8370bb4899dc2]::query::plumbing::try_execute_query::<rustc_query_impl[1e0edd06af9652a1]::DynamicConfig<rustc_query_system[63b8370bb4899dc2]::query::caches::DefaultCache<rustc_type_ir[f32108c434f59f4e]::canonical::CanonicalQueryInput<rustc_middle[fa8070f18412b0da]::ty::context::TyCtxt, rustc_middle[fa8070f18412b0da]::ty::ParamEnvAnd<rustc_middle[fa8070f18412b0da]::ty::predicate::Predicate>>, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 2usize]>>, false, false, false>, rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt, true>
  10:     0x7ef03270fd85 - rustc_query_impl[1e0edd06af9652a1]::query_impl::evaluate_obligation::get_query_incr::__rust_end_short_backtrace
  11:     0x7ef032baaeae - <rustc_trait_selection[d035bd7351711dff]::traits::fulfill::FulfillProcessor as rustc_data_structures[30a19619986f318]::obligation_forest::ObligationProcessor>::process_obligation
  12:     0x7ef03220f17f - <rustc_data_structures[30a19619986f318]::obligation_forest::ObligationForest<rustc_trait_selection[d035bd7351711dff]::traits::fulfill::PendingPredicateObligation>>::process_obligations::<rustc_trait_selection[d035bd7351711dff]::traits::fulfill::FulfillProcessor>
  13:     0x7ef032650347 - <rustc_trait_selection[d035bd7351711dff]::traits::fulfill::FulfillmentContext<rustc_trait_selection[d035bd7351711dff]::traits::FulfillmentError> as rustc_infer[1161895a0fa9626d]::traits::engine::TraitEngine<rustc_trait_selection[d035bd7351711dff]::traits::FulfillmentError>>::select_all_or_error
  14:     0x7ef032ad2bce - rustc_hir_analysis[200ebf77cfece739]::check::compare_impl_item::check_type_bounds
  15:     0x7ef032ac82bc - rustc_hir_analysis[200ebf77cfece739]::check::compare_impl_item::compare_impl_item
  16:     0x7ef032ac64b7 - rustc_query_impl[1e0edd06af9652a1]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[1e0edd06af9652a1]::query_impl::compare_impl_item::dynamic_query::{closure#2}::{closure#0}, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 1usize]>>
  17:     0x7ef03270d2aa - rustc_query_system[63b8370bb4899dc2]::query::plumbing::try_execute_query::<rustc_query_impl[1e0edd06af9652a1]::DynamicConfig<rustc_data_structures[30a19619986f318]::vec_cache::VecCache<rustc_span[a6bcc981ad5e83db]::def_id::LocalDefId, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[63b8370bb4899dc2]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt, true>
  18:     0x7ef03270f4f6 - rustc_query_impl[1e0edd06af9652a1]::query_impl::compare_impl_item::get_query_incr::__rust_end_short_backtrace
  19:     0x7ef02f991f83 - rustc_hir_analysis[200ebf77cfece739]::check::check::check_item_type
  20:     0x7ef02f9684fb - rustc_hir_analysis[200ebf77cfece739]::check::wfcheck::check_well_formed
  21:     0x7ef032c762b7 - rustc_query_impl[1e0edd06af9652a1]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[1e0edd06af9652a1]::query_impl::check_well_formed::dynamic_query::{closure#2}::{closure#0}, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 1usize]>>
  22:     0x7ef03270d661 - rustc_query_system[63b8370bb4899dc2]::query::plumbing::try_execute_query::<rustc_query_impl[1e0edd06af9652a1]::DynamicConfig<rustc_data_structures[30a19619986f318]::vec_cache::VecCache<rustc_span[a6bcc981ad5e83db]::def_id::LocalDefId, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[63b8370bb4899dc2]::dep_graph::graph::DepNodeIndex>, false, false, false>, rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt, true>
  23:     0x7ef0331f1954 - rustc_query_impl[1e0edd06af9652a1]::plumbing::force_from_dep_node::<rustc_query_impl[1e0edd06af9652a1]::DynamicConfig<rustc_data_structures[30a19619986f318]::vec_cache::VecCache<rustc_span[a6bcc981ad5e83db]::def_id::LocalDefId, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 1usize]>, rustc_query_system[63b8370bb4899dc2]::dep_graph::graph::DepNodeIndex>, false, false, false>>
  24:     0x7ef0331f17ad - <rustc_query_impl[1e0edd06af9652a1]::plumbing::query_callback<rustc_query_impl[1e0edd06af9652a1]::query_impl::check_well_formed::QueryType>::{closure#0} as core[c7a133740aa39aee]::ops::function::FnOnce<(rustc_middle[fa8070f18412b0da]::ty::context::TyCtxt, rustc_query_system[63b8370bb4899dc2]::dep_graph::dep_node::DepNode)>>::call_once
  25:     0x7ef03221fa7f - <rustc_query_system[63b8370bb4899dc2]::dep_graph::graph::DepGraphData<rustc_middle[fa8070f18412b0da]::dep_graph::DepsType>>::try_mark_previous_green::<rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt>
  26:     0x7ef03221f1ae - <rustc_query_system[63b8370bb4899dc2]::dep_graph::graph::DepGraphData<rustc_middle[fa8070f18412b0da]::dep_graph::DepsType>>::try_mark_green::<rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt>
  27:     0x7ef032cf317d - rustc_query_system[63b8370bb4899dc2]::query::plumbing::ensure_must_run::<rustc_query_impl[1e0edd06af9652a1]::DynamicConfig<rustc_query_system[63b8370bb4899dc2]::query::caches::DefaultCache<rustc_span[a6bcc981ad5e83db]::def_id::LocalModDefId, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt>
  28:     0x7ef03312c993 - rustc_query_impl[1e0edd06af9652a1]::query_impl::check_mod_type_wf::get_query_incr::__rust_end_short_backtrace
  29:     0x7ef0325c5b4d - rustc_hir_analysis[200ebf77cfece739]::check_crate
  30:     0x7ef0325cfc5c - rustc_interface[3b74b9441e612cca]::passes::run_required_analyses
  31:     0x7ef033180e7a - rustc_interface[3b74b9441e612cca]::passes::analysis
  32:     0x7ef033180e59 - rustc_query_impl[1e0edd06af9652a1]::plumbing::__rust_begin_short_backtrace::<rustc_query_impl[1e0edd06af9652a1]::query_impl::analysis::dynamic_query::{closure#2}::{closure#0}, rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 0usize]>>
  33:     0x7ef03317c759 - rustc_query_system[63b8370bb4899dc2]::query::plumbing::try_execute_query::<rustc_query_impl[1e0edd06af9652a1]::DynamicConfig<rustc_query_system[63b8370bb4899dc2]::query::caches::SingleCache<rustc_middle[fa8070f18412b0da]::query::erase::Erased<[u8; 0usize]>>, false, false, false>, rustc_query_impl[1e0edd06af9652a1]::plumbing::QueryCtxt, true>
  34:     0x7ef03317c162 - rustc_query_impl[1e0edd06af9652a1]::query_impl::analysis::get_query_incr::__rust_end_short_backtrace
  35:     0x7ef03328923c - rustc_interface[3b74b9441e612cca]::passes::create_and_enter_global_ctxt::<core[c7a133740aa39aee]::option::Option<rustc_interface[3b74b9441e612cca]::queries::Linker>, rustc_driver_impl[f8acc18714ba66d9]::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}
  36:     0x7ef03327caeb - rustc_interface[3b74b9441e612cca]::interface::run_compiler::<(), rustc_driver_impl[f8acc18714ba66d9]::run_compiler::{closure#0}>::{closure#1}
  37:     0x7ef033107550 - std[54256809445ede48]::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface[3b74b9441e612cca]::util::run_in_thread_with_globals<rustc_interface[3b74b9441e612cca]::util::run_in_thread_pool_with_globals<rustc_interface[3b74b9441e612cca]::interface::run_compiler<(), rustc_driver_impl[f8acc18714ba66d9]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
  38:     0x7ef033107974 - <<std[54256809445ede48]::thread::Builder>::spawn_unchecked_<rustc_interface[3b74b9441e612cca]::util::run_in_thread_with_globals<rustc_interface[3b74b9441e612cca]::util::run_in_thread_pool_with_globals<rustc_interface[3b74b9441e612cca]::interface::run_compiler<(), rustc_driver_impl[f8acc18714ba66d9]::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core[c7a133740aa39aee]::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
  39:     0x7ef03310832f - std::sys::pal::unix::thread::Thread::new::thread_start::h208202f9d25af663
  40:     0x7ef02d297d02 - start_thread
  41:     0x7ef02d3173ac - __GI___clone3
  42:                0x0 - <unknown>


rustc version: 1.87.0-nightly (f280acf4c 2025-02-19)
platform: x86_64-unknown-linux-gnu

query stack during panic:
#0 [evaluate_obligation] evaluating trait selection obligation `_::HelpLinkEncoder: core::marker::Sync`
#1 [compare_impl_item] checking assoc item `_::<impl at sample/src/lib.rs:7:1: 7:37>::Encoder` is compatible with trait definition
#2 [check_well_formed] checking that `_::<impl at sample/src/lib.rs:7:1: 7:37>` is well-formed
#3 [analysis] running analysis passes on this crate
end of query stack

[matteopolak]

Unfortunately the best I can do automatically with the macro is to derive the enabled traits - users will need to add whichever attributes are required for each enabled derive macro (like #[serde(borrow)]).

That ICE is a compiler bug though, I would recommend reporting it if it hasn't been done already :)

I'm not sure which features you have enabled for the second one, but a few of the formats do not support borrowing from input - you will likely want to use Cow<'a, str> instead of str (which is also needed with e.g. serde_json if the input has escaped characters).