Cargo panics when using `-Z rustdoc-scrape-examples=examples`

[AaronErhardt]

Problem

Cargo (nightly) panics when I use -Z rustdoc-scrape-examples=examples. This issue first appeared yesterday in the documentation workflow of Relm4 without any changes to the CI configuration, so this must be related to a recent change in cargo or rustc.

Steps

1. Clone Relm4
2. Run cargo +nightly doc -Z rustdoc-scrape-examples=examples (you might need to have gtk4 installed)

Possible Solution(s)

No response

Notes

Backtrace

thread 'main' panicked at 'activated_features for invalid package: features did not find PackageId { name: "relm4-examples", version: "0.4.0", source: "/.../relm4/relm4-examples" } HostDep

Stack backtrace:
   0: <anyhow::Error>::msg::<alloc::string::String>
   1: <cargo::core::resolver::features::ResolvedFeatures>::activated_features_int
   2: cargo::core::compiler::unit_dependencies::new_unit_dep_with_profile
   3: cargo::core::compiler::unit_dependencies::compute_deps
   4: cargo::core::compiler::unit_dependencies::deps_of
   5: cargo::core::compiler::unit_dependencies::deps_of
   6: cargo::core::compiler::unit_dependencies::deps_of
   7: cargo::core::compiler::unit_dependencies::deps_of_roots
   8: cargo::core::compiler::unit_dependencies::build_unit_dependencies
   9: cargo::ops::cargo_compile::create_bcx
  10: cargo::ops::cargo_compile::compile_ws
  11: cargo::ops::cargo_compile::compile
  12: cargo::ops::cargo_doc::doc
  13: cargo::commands::doc::exec
  14: cargo::cli::main
  15: cargo::main
  16: std::sys_common::backtrace::__rust_begin_short_backtrace::<fn(), ()>
  17: std::rt::lang_start::<()>::{closure#0}
  18: core::ops::function::impls::<impl core::ops::function::FnOnce<A> for &F>::call_once
             at /rustc/8f36334ca939a67cce3f37f24953ff6f2d3f3d33/library/core/src/ops/function.rs:280:13
  19: std::panicking::try::do_call
             at /rustc/8f36334ca939a67cce3f37f24953ff6f2d3f3d33/library/std/src/panicking.rs:492:40
  20: std::panicking::try
             at /rustc/8f36334ca939a67cce3f37f24953ff6f2d3f3d33/library/std/src/panicking.rs:456:19
  21: std::panic::catch_unwind
             at /rustc/8f36334ca939a67cce3f37f24953ff6f2d3f3d33/library/std/src/panic.rs:137:14
  22: std::rt::lang_start_internal::{{closure}}
             at /rustc/8f36334ca939a67cce3f37f24953ff6f2d3f3d33/library/std/src/rt.rs:128:48
  23: std::panicking::try::do_call
             at /rustc/8f36334ca939a67cce3f37f24953ff6f2d3f3d33/library/std/src/panicking.rs:492:40
  24: std::panicking::try
             at /rustc/8f36334ca939a67cce3f37f24953ff6f2d3f3d33/library/std/src/panicking.rs:456:19
  25: std::panic::catch_unwind
             at /rustc/8f36334ca939a67cce3f37f24953ff6f2d3f3d33/library/std/src/panic.rs:137:14
  26: std::rt::lang_start_internal
             at /rustc/8f36334ca939a67cce3f37f24953ff6f2d3f3d33/library/std/src/rt.rs:128:20
  27: main
  28: __libc_start_call_main
  29: __libc_start_main_impl
  30: <unknown>', src/tools/cargo/src/cargo/core/resolver/features.rs:318:14
stack backtrace:
   0: rust_begin_unwind
             at /rustc/8f36334ca939a67cce3f37f24953ff6f2d3f3d33/library/std/src/panicking.rs:584:5
   1: core::panicking::panic_fmt
             at /rustc/8f36334ca939a67cce3f37f24953ff6f2d3f3d33/library/core/src/panicking.rs:143:14
   2: core::result::unwrap_failed
             at /rustc/8f36334ca939a67cce3f37f24953ff6f2d3f3d33/library/core/src/result.rs:1785:5
   3: cargo::core::compiler::unit_dependencies::new_unit_dep_with_profile
   4: cargo::core::compiler::unit_dependencies::compute_deps
   5: cargo::core::compiler::unit_dependencies::deps_of
   6: cargo::core::compiler::unit_dependencies::deps_of
   7: cargo::core::compiler::unit_dependencies::deps_of
   8: cargo::core::compiler::unit_dependencies::deps_of_roots
   9: cargo::core::compiler::unit_dependencies::build_unit_dependencies
  10: cargo::ops::cargo_compile::create_bcx
  11: cargo::ops::cargo_compile::compile_ws
  12: cargo::ops::cargo_compile::compile
  13: cargo::ops::cargo_doc::doc
  14: cargo::commands::doc::exec
  15: cargo::cli::main
  16: cargo::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Version

cargo 1.62.0-nightly (e2e2ddd 2022-04-05)

[ehuss]

cc @willcrichton

[willcrichton]

I will take a look, thanks for the report @AaronErhardt.