[ICE]: `cargo doc` fails for the crate `galvyn`

[gammelalf]

Hi,

my crate galvyn does not build on docs.rs due to a compiler error.

I can reproduce it locally with a simple cargo +nightly doc.

The stable rust version seems fine.

Below are the outputs and versions for my local machine. You can also check https://docs.rs/crate/galvyn/latest/builds.

Code

I don't have a small snippet triggering the error.

If I find the time for it, I will search for one.

Meta

rustc --version --verbose:

rustc 1.101.0-nightly (5c543b0b8 2026-09-29)
binary: rustc
commit-hash: 5c543b0b8c73c7b72bc8284ced4fb22ead15734d
commit-date: 2026-09-29
host: x86_64-unknown-linux-gnu
release: 1.101.0-nightly
LLVM version: 23.1.1

Error output

note: no errors encountered even though delayed bugs were created

note: those delayed bugs will now be shown as internal compiler errors

error: internal compiler error: did not expect successful goal when collecting ambiguity errors for `Binder { value: OutlivesClause(Alias(No, Alias { kind: Projection { def_id: DefId(26:11 ~ tower_service[3c8e]::Service::Future) }, args: [axum::Router<()>, axum::http::Request<axum::body::Body>], .. }), 'static), bound_vars: [] }`
  |
  = note: delayed at /rustc-dev/5c543b0b8c73c7b72bc8284ced4fb22ead15734d/compiler/rustc_trait_selection/src/solve/fulfill/derive_errors.rs:140:29 - disabled backtrace

error: internal compiler error: did not expect successful goal when collecting ambiguity errors for `Binder { value: OutlivesClause(Alias(No, Alias { kind: Projection { def_id: DefId(26:11 ~ tower_service[3c8e]::Service::Future) }, args: [axum::routing::RouterAsService<'?0, axum::body::Body, ()>, axum::http::Request<axum::body::Body>], .. }), 'static), bound_vars: [] }`
  |
  = note: delayed at /rustc-dev/5c543b0b8c73c7b72bc8284ced4fb22ead15734d/compiler/rustc_trait_selection/src/solve/fulfill/derive_errors.rs:140:29 - disabled backtrace

error: internal compiler error: did not expect successful goal when collecting ambiguity errors for `Binder { value: OutlivesClause(Alias(No, Alias { kind: Projection { def_id: DefId(26:11 ~ tower_service[3c8e]::Service::Future) }, args: [axum::routing::RouterIntoService<axum::body::Body, ()>, axum::http::Request<axum::body::Body>], .. }), 'static), bound_vars: [] }`
  |
  = note: delayed at /rustc-dev/5c543b0b8c73c7b72bc8284ced4fb22ead15734d/compiler/rustc_trait_selection/src/solve/fulfill/derive_errors.rs:140:29 - disabled backtrace

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

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

note: please attach the file at `/home/user/git/galvyn/rustc-ice-2026-09-30T09_10_04-288396.txt` to your bug report

note: rustc 1.101.0-nightly (5c543b0b8 2026-09-29) running on x86_64-unknown-linux-gnu

note: compiler flags: --crate-type lib

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

query stack during panic:
end of query stack
error: could not document `galvyn`

Backtrace

error: internal compiler error: did not expect successful goal when collecting ambiguity errors for `Binder { value: OutlivesClause(Alias(No, Alias { kind: Projection { def_id: DefId(26:11 ~ tower_service[3c8e]::Service::Future) }, args: [axum::Router<()>, axum::http::Request<axum::body::Body>], .. }), 'static), bound_vars: [] }`
  |
  = note: delayed at /rustc-dev/5c543b0b8c73c7b72bc8284ced4fb22ead15734d/compiler/rustc_trait_selection/src/solve/fulfill/derive_errors.rs:140:29
             0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
             1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
             2: <rustc_errors::diagnostic::Diag>::emit_err
             3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
             4: rustc_trait_selection::solve::fulfill::collect_remaining_errors_impl::<rustc_infer::traits::engine::ScrubbedTraitError>
             5: <rustc_trait_selection::traits::engine::FulfillmentEngine<rustc_infer::traits::engine::ScrubbedTraitError> as rustc_infer::traits::engine::TraitEngine<rustc_infer::traits::engine::ScrubbedTraitError>>::evaluate_obligations_error_on_ambiguity
             6: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation
             7: rustdoc::clean::utils::synthesize_auto_trait_and_blanket_impls
             8: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
             9: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            10: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            11: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            12: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            13: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            14: <rustc_session::session::Session>::time::<rustdoc::clean::types::Crate, rustdoc::passes::run::{closure#0}>
            15: rustdoc::core::run_global_ctxt
            16: rustdoc::main_args::{closure#2}::{closure#0}
            17: rustc_interface::interface::run_compiler::<(), rustdoc::main_args::{closure#2}>::{closure#2}
            18: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustdoc::main_args::{closure#2}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
            19: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustdoc::main_args::{closure#2}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
            20: <std::sys::thread::unix::Thread>::new::thread_start
            21: <unknown>
            22: <unknown>
          

error: internal compiler error: did not expect successful goal when collecting ambiguity errors for `Binder { value: OutlivesClause(Alias(No, Alias { kind: Projection { def_id: DefId(26:11 ~ tower_service[3c8e]::Service::Future) }, args: [axum::routing::RouterAsService<'?0, axum::body::Body, ()>, axum::http::Request<axum::body::Body>], .. }), 'static), bound_vars: [] }`
  |
  = note: delayed at /rustc-dev/5c543b0b8c73c7b72bc8284ced4fb22ead15734d/compiler/rustc_trait_selection/src/solve/fulfill/derive_errors.rs:140:29
             0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
             1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
             2: <rustc_errors::diagnostic::Diag>::emit_err
             3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
             4: rustc_trait_selection::solve::fulfill::collect_remaining_errors_impl::<rustc_infer::traits::engine::ScrubbedTraitError>
             5: <rustc_trait_selection::traits::engine::FulfillmentEngine<rustc_infer::traits::engine::ScrubbedTraitError> as rustc_infer::traits::engine::TraitEngine<rustc_infer::traits::engine::ScrubbedTraitError>>::evaluate_obligations_error_on_ambiguity
             6: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation
             7: rustdoc::clean::utils::synthesize_auto_trait_and_blanket_impls
             8: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
             9: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            10: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            11: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            12: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            13: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            14: <rustc_session::session::Session>::time::<rustdoc::clean::types::Crate, rustdoc::passes::run::{closure#0}>
            15: rustdoc::core::run_global_ctxt
            16: rustdoc::main_args::{closure#2}::{closure#0}
            17: rustc_interface::interface::run_compiler::<(), rustdoc::main_args::{closure#2}>::{closure#2}
            18: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustdoc::main_args::{closure#2}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
            19: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustdoc::main_args::{closure#2}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
            20: <std::sys::thread::unix::Thread>::new::thread_start
            21: <unknown>
            22: <unknown>
          

error: internal compiler error: did not expect successful goal when collecting ambiguity errors for `Binder { value: OutlivesClause(Alias(No, Alias { kind: Projection { def_id: DefId(26:11 ~ tower_service[3c8e]::Service::Future) }, args: [axum::routing::RouterIntoService<axum::body::Body, ()>, axum::http::Request<axum::body::Body>], .. }), 'static), bound_vars: [] }`
  |
  = note: delayed at /rustc-dev/5c543b0b8c73c7b72bc8284ced4fb22ead15734d/compiler/rustc_trait_selection/src/solve/fulfill/derive_errors.rs:140:29
             0: <rustc_errors::DiagCtxtInner>::emit_diagnostic
             1: <rustc_errors::DiagCtxtHandle>::emit_diagnostic
             2: <rustc_errors::diagnostic::Diag>::emit_err
             3: <rustc_errors::DiagCtxtHandle>::span_delayed_bug::<rustc_span::span_encoding::Span, alloc::string::String>
             4: rustc_trait_selection::solve::fulfill::collect_remaining_errors_impl::<rustc_infer::traits::engine::ScrubbedTraitError>
             5: <rustc_trait_selection::traits::engine::FulfillmentEngine<rustc_infer::traits::engine::ScrubbedTraitError> as rustc_infer::traits::engine::TraitEngine<rustc_infer::traits::engine::ScrubbedTraitError>>::evaluate_obligations_error_on_ambiguity
             6: <rustc_infer::infer::InferCtxt as rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt>::evaluate_obligation
             7: rustdoc::clean::utils::synthesize_auto_trait_and_blanket_impls
             8: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
             9: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            10: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            11: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            12: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            13: <rustdoc::passes::collect_trait_impls::SyntheticImplCollector as rustdoc::visit::DocVisitor>::visit_item
            14: <rustc_session::session::Session>::time::<rustdoc::clean::types::Crate, rustdoc::passes::run::{closure#0}>
            15: rustdoc::core::run_global_ctxt
            16: rustdoc::main_args::{closure#2}::{closure#0}
            17: rustc_interface::interface::run_compiler::<(), rustdoc::main_args::{closure#2}>::{closure#2}
            18: std::sys::backtrace::__rust_begin_short_backtrace::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustdoc::main_args::{closure#2}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>
            19: <std::thread::lifecycle::spawn_unchecked<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustdoc::main_args::{closure#2}>::{closure#2}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}, ()>::{closure#1} as core::ops::function::FnOnce<()>>::call_once::{shim:vtable#0}
            20: <std::sys::thread::unix::Thread>::new::thread_start
            21: <unknown>
            22: <unknown>

[apiraino]

just by looking at the error, I think we have already other reports and possibly this could be fixed by #162782

[gammelalf]

Sounds plausible.

I reduced galvyn to the minimal code:

pub mod core {
    pub use galvyn_core::*;
}

galvyn-core contains several definition similar to the example of #162782.

However, galvyn-core on its own works.

[gammelalf]

I reduced it some more:

// galvyn/src/lib.rs
pub mod core {
    pub use galvyn_core::*;
}

// galvyn-core/src/lib.rs

use std::convert::Infallible;

use axum::extract::Request;
use axum::response::IntoResponse;
use tower::Service;

pub mod re_exports {
    pub use axum;
}

/// Trait alias for [`tower::Service`] constraint to be used by axum
pub trait AxumService:
    Service<Request, Error = Infallible, Response: IntoResponse, Future: Send + 'static>
{
}
impl<T> AxumService for T where
    T: Service<Request, Error = Infallible, Response: IntoResponse, Future: Send + 'static>
{
}

I tried inline galvyn-core into galvyn, the error would be gone.
I also tried inlining the tower Service trait, the error would be gone.
And this reduced galvyn-core on its own works fine.

https://github.com/myOmikron/galvyn/tree/ice-example

[gammelalf]

Final minimal example: (produced by claude)

pub trait Tr {
    type A;
}

pub struct S<T>(T);

impl Tr for S<()> {
    type A = ();
}

pub trait Blanket {}

impl<T: Tr<A: 'static>> Blanket for T {}

This is almost exactly the same as in #162782

FYI
(According to claude) The re-exports were necessary in my initial example to cause rustdoc to generate a page for the struct with a blanket implementation for the two traits. This can also be done by declaring everything in a single crate.