ICE while bootstrapping: entered unreachable code', src/librustc/middle/cstore.rs:45:5

[matthiaskrgr]

I was switching from a local branch to master and building when the compiler ICE'd.
The compiler was at c839a7b at the time of the build.

Error output

   Compiling rustc-std-workspace-core v1.99.0 (/home/matthias/vcs/github/rust/src/tools/rustc-std-workspace-core)
thread 'rustc' panicked at 'internal error: entered unreachable code', /home/matthias/vcs/github/rust/src/librustc/middle/cstore.rs:45:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

error: internal compiler error: unexpected panic

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

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.43.0-dev running on x86_64-unknown-linux-gnu

note: compiler flags: -Z macro-backtrace -Z save-analysis -Z binary-dep-depinfo -Z force-unstable-if-unmarked -C opt-level=3 -C debuginfo=0 -C target-cpu=native -C link-args=-Wl,-rpath,$ORIGIN/../lib -C prefer-dynamic -C debug-assertions=n --crate-type rlib

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

Backtrace

Updating only changed submodules
Submodules updated in 0.03 seconds
    Finished dev [unoptimized] target(s) in 0.12s
Building stage0 std artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
    Finished release [optimized] target(s) in 0.19s
Copying stage0 std from stage0 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu / x86_64-unknown-linux-gnu)
Building stage0 compiler artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
    Finished release [optimized] target(s) in 0.17s
Installing libLLVM.so to stage 0 (x86_64-unknown-linux-gnu)
Copying stage0 rustc from stage0 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu / x86_64-unknown-linux-gnu)
Assembling stage1 compiler (x86_64-unknown-linux-gnu)
Building stage1 std artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
   Compiling compiler_builtins v0.1.25
   Compiling libc v0.2.66
thread 'rustc' panicked at 'internal error: entered unreachable code', /home/matthias/vcs/github/rust/src/librustc/middle/cstore.rs:45:5
stack backtrace:
   0: <std::sys_common::backtrace::_print::DisplayBacktrace as core::fmt::Display>::fmt
   1: core::fmt::write
   2: std::io::Write::write_fmt
   3: std::panicking::default_hook::{{closure}}
   4: std::panicking::default_hook
   5: rustc_driver::report_ice
   6: std::panicking::rust_panic_with_hook
   7: std::panicking::begin_panic
   8: <rustc_metadata::rmeta::CrateDep as serialize::serialize::Decodable>::decode
   9: <core::iter::adapters::Map<I,F> as core::iter::traits::iterator::Iterator>::fold
  10: <alloc::vec::Vec<T> as alloc::vec::SpecExtend<T,I>>::from_iter
  11: rustc_metadata::creader::CrateLoader::maybe_resolve_crate
  12: rustc_metadata::creader::CrateLoader::process_extern_crate
  13: <rustc_resolve::build_reduced_graph::BuildReducedGraphVisitor as rustc_ast::visit::Visitor>::visit_item
  14: rustc_expand::expand::AstFragment::visit_with
  15: rustc_resolve::macros::<impl rustc_expand::base::Resolver for rustc_resolve::Resolver>::visit_ast_fragment_with_placeholders
  16: rustc_expand::expand::MacroExpander::collect_invocations
  17: rustc_expand::expand::MacroExpander::fully_expand_fragment
  18: rustc_expand::expand::MacroExpander::expand_crate
  19: rustc_session::utils::<impl rustc_session::session::Session>::time
  20: rustc_interface::passes::configure_and_expand_inner
  21: rustc_interface::passes::configure_and_expand::{{closure}}
  22: rustc_data_structures::box_region::PinnedGenerator<I,A,R>::new
  23: rustc_interface::passes::configure_and_expand
  24: rustc_interface::queries::Queries::expansion
  25: rustc_interface::interface::run_compiler_in_existing_thread_pool
  26: rustc_ast::attr::with_globals
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

error: internal compiler error: unexpected panic

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

note: we would appreciate a bug report: https://github.com/rust-lang/rust/blob/master/CONTRIBUTING.md#bug-reports

note: rustc 1.43.0-dev running on x86_64-unknown-linux-gnu

note: compiler flags: -Z macro-backtrace -Z save-analysis -Z binary-dep-depinfo -Z force-unstable-if-unmarked -C opt-level=3 -C debuginfo=0 -C target-cpu=native -C link-args=-Wl,-rpath,$ORIGIN/../lib -C prefer-dynamic -C debug-assertions=n --crate-type rlib

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

query stack during panic:
end of query stack
error: could not compile `libc`.
warning: build failed, waiting for other jobs to finish...
error: build failed
command did not execute successfully: "/home/matthias/vcs/github/rust/build/x86_64-unknown-linux-gnu/stage0/bin/cargo" "build" "-Zconfig-profile" "--target" "x86_64-unknown-linux-gnu" "-Zbinary-dep-depinfo" "-j" "4" "--release" "--features" "panic-unwind backtrace profiler compiler-builtins-c" "--manifest-path" "/home/matthias/vcs/github/rust/src/libtest/Cargo.toml" "--message-format" "json-render-diagnostics"
expected success, got: exit code: 101
failed to run: /home/matthias/vcs/github/rust/build/bootstrap/debug/bootstrap build
Build completed unsuccessfully in 0:00:02

[matthiaskrgr]

Might be another incremental compilation issue, I'm not sure how to produce a reproduction pattern right now :/

[jyn514]

@matthiaskrgr have you run into this issue since? If not, it's probably a duplicate of #76720.

[matthiaskrgr]

I don't remember running into this issue recently.