Skip to content

Failed to build core crate with -C opt-level=0 #789

@thesamesam

Description

@thesamesam

In one environment, I use RUSTFLAGS="-C opt-level=0 -C debuginfo=0". Building rustc with this when using rustc_codegen_gcc, I get a failure to build core:

thread 'rustc' (75759) panicked at /rustc-dev/67c208e9eec6b5add33b94f593fe18b23bf9fa3c/compiler/rustc_codegen_ssa/src/mir/rvalue.rs:1034:5: assertion `left == right` failed left: __int32_t __attribute__((aligned(4))) * __attribute__((aligned(8))) right: void * stack backtrace: 0: __rustc::rust_begin_unwind 1: core::panicking::panic_fmt.localalias 2: core::panicking::assert_failed_inner 3: core::panicking::assert_failed::<gccjit::types::Type, gccjit::types::Type> 4: rustc_codegen_ssa::mir::rvalue::transmute_scalar::<rustc_codegen_gcc::builder::Builder> 5: <rustc_codegen_ssa::mir::FunctionCx<rustc_codegen_gcc::builder::Builder>>::codegen_transmute_operand 6: <rustc_codegen_ssa::mir::FunctionCx<rustc_codegen_gcc::builder::Builder>>::codegen_rvalue_operand 7: <rustc_codegen_ssa::mir::FunctionCx<rustc_codegen_gcc::builder::Builder>>::codegen_statement 8: <rustc_codegen_ssa::mir::FunctionCx<rustc_codegen_gcc::builder::Builder>>::codegen_block.localalias 9: rustc_codegen_ssa::mir::codegen_mir::<rustc_codegen_gcc::builder::Builder> 10: rustc_codegen_ssa::base::codegen_instance::<rustc_codegen_gcc::builder::Builder> 11: <rustc_middle::mir::mono::MonoItem as rustc_codegen_ssa::mono_item::MonoItemExt>::define::<rustc_codegen_gcc::builder::Builder> 12: rustc_codegen_gcc::base::compile_codegen_unit::module_codegen 13: <rustc_query_system::dep_graph::graph::DepGraph<rustc_middle::dep_graph::DepsType>>::with_task::<rustc_middle::ty::context::TyCtxt, (rustc_span::symbol::Symbol, rustc_codegen_gcc::LockedTargetInfo), rustc_codegen_ssa::ModuleCodegen<rustc_codegen_gcc::GccContext>> 14: rustc_codegen_gcc::base::compile_codegen_unit 15: <rustc_codegen_gcc::GccCodegenBackend as rustc_codegen_ssa::traits::backend::ExtraBackendMethods>::compile_codegen_unit 16: rustc_codegen_ssa::base::codegen_crate::<rustc_codegen_gcc::GccCodegenBackend> 17: <rustc_codegen_gcc::GccCodegenBackend as rustc_codegen_ssa::traits::backend::CodegenBackend>::codegen_crate 18: rustc_interface::passes::start_codegen::{closure#0} 19: <rustc_session::session::Session>::time::<alloc::boxed::Box<dyn core::any::Any>, rustc_interface::passes::start_codegen::{closure#0}> 20: rustc_interface::passes::start_codegen 21: <rustc_interface::queries::Linker>::codegen_and_build_linker 22: rustc_driver_impl::run_compiler::{closure#0}::{closure#2} 23: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0} 24: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>::{closure#1} 25: rustc_middle::ty::context::tls::enter_context::<<rustc_middle::ty::context::GlobalCtxt>::enter<rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>::{closure#1}, core::option::Option<rustc_interface::queries::Linker>>::{closure#0} 26: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::try_with::<rustc_middle::ty::context::tls::enter_context<<rustc_middle::ty::context::GlobalCtxt>::enter<rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>::{closure#1}, core::option::Option<rustc_interface::queries::Linker>>::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>.localalias 27: <std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<<rustc_middle::ty::context::GlobalCtxt>::enter<rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>::{closure#1}, core::option::Option<rustc_interface::queries::Linker>>::{closure#0}, core::option::Option<rustc_interface::queries::Linker>> 28: rustc_middle::ty::context::tls::enter_context::<<rustc_middle::ty::context::GlobalCtxt>::enter<rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>::{closure#1}, core::option::Option<rustc_interface::queries::Linker>> 29: <rustc_middle::ty::context::GlobalCtxt>::enter::<rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}, core::option::Option<rustc_interface::queries::Linker>>.localalias 30: <rustc_middle::ty::context::TyCtxt>::create_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2}::{closure#0}> 31: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2} 32: <rustc_interface::passes::create_and_enter_global_ctxt<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}>::{closure#2} as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once::{shim:vtable#0} 33: <alloc::boxed::Box<dyn for<'a> core::ops::function::FnOnce<(&'a rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy>, &'a std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt<'a>>, &'a rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena<'a>>, &'a rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena<'a>>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}), Output = core::option::Option<rustc_interface::queries::Linker>>> as core::ops::function::FnOnce<(&rustc_session::session::Session, rustc_middle::ty::context::CurrentGcx, alloc::sync::Arc<rustc_data_structures::jobserver::Proxy>, &std::sync::once_lock::OnceLock<rustc_middle::ty::context::GlobalCtxt>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_middle::arena::Arena>, &rustc_data_structures::sync::worker_local::WorkerLocal<rustc_hir::Arena>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2})>>::call_once 34: rustc_interface::passes::create_and_enter_global_ctxt::<core::option::Option<rustc_interface::queries::Linker>, rustc_driver_impl::run_compiler::{closure#0}::{closure#2}> 35: rustc_driver_impl::run_compiler::{closure#0} 36: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}::{closure#0}.localalias 37: <core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}::{closure#0}> as core::ops::function::FnOnce<()>>::call_once 38: std::panicking::catch_unwind::do_call::<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}::{closure#0}>, ()> 39: __rust_try 40: std::panic::catch_unwind::<core::panic::unwind_safe::AssertUnwindSafe<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}::{closure#0}>, ()> 41: rustc_interface::interface::run_compiler::<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1} 42: rustc_interface::util::run_in_thread_pool_with_globals::<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}.localalias 43: rustc_interface::util::run_in_thread_with_globals::<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0} 44: <scoped_tls::ScopedKey<rustc_span::SessionGlobals>>::set::<rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}, ()> 45: rustc_span::create_session_globals_then::<(), rustc_interface::util::run_in_thread_with_globals<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0}::{closure#0}> 46: rustc_interface::util::run_in_thread_with_globals::<rustc_interface::util::run_in_thread_pool_with_globals<rustc_interface::interface::run_compiler<(), rustc_driver_impl::run_compiler::{closure#0}>::{closure#1}, ()>::{closure#0}, ()>::{closure#0}::{closure#0} note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace. 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 `/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/rustc-ice-2025-10-27T12_31_28-75726.txt` to your bug report note: compiler flags: --crate-type lib -C opt-level=3 -C embed-bitcode=no -C codegen-units=1 -C linker=x86_64-pc-linux-gnu-gcc -C opt-level=0 -C debuginfo=0 -C symbol-mangling-version=legacy -Z unstable-options -Z macro-backtrace -C split-debuginfo=off -C prefer-dynamic -Z inline-mir -Z inline-mir-preserve-debug -Z mir_strip_debuginfo=locals-in-tiny-functions -C link-args=-Wl,-z,origin -C link-args=-Wl,-rpath,$ORIGIN/../lib -C embed-bitcode=yes -C lto=off -Z unstable-options -C force-frame-pointers=non-leaf -Z crate-attr=doc(html_root_url="https://doc.rust-lang.org/nightly/") -Z binary-dep-depinfo -Z force-unstable-if-unmarked note: some of the compiler flags provided by cargo are hidden query stack during panic: end of query stack Did not run successfully: exit status: 101 LD_LIBRARY_PATH="/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/x86_64-unknown-linux-gnu/stage1/lib:/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/x86_64-unknown-linux-gnu/stage1-std/release/deps" "/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/x86_64-unknown-linux-gnu/stage1/bin/rustc" "--crate-name" "core" "--edition=2024" "library/core/src/lib.rs" "--error-format=json" "--json=diagnostic-rendered-ansi,artifacts,future-incompat" "--crate-type" "lib" "--emit=dep-info,metadata,link" "-C" "opt-level=3" "-C" "embed-bitcode=no" "-C" "codegen-units=1" "--warn=unexpected_cfgs" "--check-cfg" "cfg(no_fp_fmt_parse)" "--check-cfg" "cfg(feature, values(any()))" "--check-cfg" "cfg(target_has_reliable_f16)" "--check-cfg" "cfg(target_has_reliable_f16_math)" "--check-cfg" "cfg(target_has_reliable_f128)" "--check-cfg" "cfg(target_has_reliable_f128_math)" "--check-cfg" "cfg(docsrs,test)" "--check-cfg" "cfg(feature, values(\"debug_refcell\", \"optimize_for_size\", \"panic_immediate_abort\"))" "-C" "metadata=e4c2771f4ac279b7" "-C" "extra-filename=-847cdeb8a8d320b3" "--out-dir" "/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps" "--target" "x86_64-unknown-linux-gnu" "-C" "linker=x86_64-pc-linux-gnu-gcc" "-L" "dependency=/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps" "-L" "dependency=/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/x86_64-unknown-linux-gnu/stage1-std/release/deps" "-C" "opt-level=0" "-C" "debuginfo=0" "-Lnative=/usr/lib/llvm/21/lib64" "-Csymbol-mangling-version=legacy" "--check-cfg=cfg(feature,values(any()))" "-Zunstable-options" "-Zmacro-backtrace" "-Csplit-debuginfo=off" "-Cprefer-dynamic" "-Zinline-mir" "-Zinline-mir-preserve-debug" "-Zmir_strip_debuginfo=locals-in-tiny-functions" "-Clink-args=-Wl,-z,origin" "-Clink-args=-Wl,-rpath,$ORIGIN/../lib" "-Alinker-messages" "-Cembed-bitcode=yes" "-Clto=off" "-Zunstable-options" "-Cforce-frame-pointers=non-leaf" "-Zcrate-attr=doc(html_root_url=\"https://doc.rust-lang.org/nightly/\")" "-Z" "binary-dep-depinfo" "-Wrust_2018_idioms" "-Wunused_lifetimes" "-Dwarnings" "--sysroot" "/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/x86_64-unknown-linux-gnu/stage1" "--remap-path-prefix" "/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src=/rustc/67c208e9eec6b5add33b94f593fe18b23bf9fa3c" "--remap-path-prefix" "/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/vendor=/rust/deps" "-Z" "force-unstable-if-unmarked" ------------- error: could not compile `core` (lib) Caused by: process didn't exit successfully: `CARGO=/usr/lib/rust/1.91.0/bin/cargo CARGO_CRATE_NAME=core CARGO_MANIFEST_DIR=/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/library/core CARGO_MANIFEST_PATH=/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/library/core/Cargo.toml CARGO_PKG_AUTHORS='' CARGO_PKG_DESCRIPTION='The Rust Core Library' CARGO_PKG_HOMEPAGE='' CARGO_PKG_LICENSE='MIT OR Apache-2.0' CARGO_PKG_LICENSE_FILE='' CARGO_PKG_NAME=core CARGO_PKG_README='' CARGO_PKG_REPOSITORY='https://github.com/rust-lang/rust.git' CARGO_PKG_RUST_VERSION='' CARGO_PKG_VERSION=0.0.0 CARGO_PKG_VERSION_MAJOR=0 CARGO_PKG_VERSION_MINOR=0 CARGO_PKG_VERSION_PATCH=0 CARGO_PKG_VERSION_PRE='' LD_LIBRARY_PATH=/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/x86_64-unknown-linux-gnu/stage1-std/release/deps /var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/bootstrap/debug/rustc /var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/bootstrap/debug/rustc --crate-name core --edition=2024 library/core/src/lib.rs --error-format=json --json=diagnostic-rendered-ansi,artifacts,future-incompat --crate-type lib --emit=dep-info,metadata,link -C opt-level=3 -C embed-bitcode=no -C codegen-units=1 --warn=unexpected_cfgs --check-cfg 'cfg(no_fp_fmt_parse)' --check-cfg 'cfg(feature, values(any()))' --check-cfg 'cfg(target_has_reliable_f16)' --check-cfg 'cfg(target_has_reliable_f16_math)' --check-cfg 'cfg(target_has_reliable_f128)' --check-cfg 'cfg(target_has_reliable_f128_math)' --check-cfg 'cfg(docsrs,test)' --check-cfg 'cfg(feature, values("debug_refcell", "optimize_for_size", "panic_immediate_abort"))' -C metadata=e4c2771f4ac279b7 -C extra-filename=-847cdeb8a8d320b3 --out-dir /var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps --target x86_64-unknown-linux-gnu -C linker=x86_64-pc-linux-gnu-gcc -L dependency=/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/x86_64-unknown-linux-gnu/stage1-std/x86_64-unknown-linux-gnu/release/deps -L dependency=/var/tmp/portage/dev-lang/rust-1.91.0_beta20251009/work/rustc-beta-src/build/x86_64-unknown-linux-gnu/stage1-std/release/deps -C opt-level=0 -C debuginfo=0 -Lnative=/usr/lib/llvm/21/lib64 -Csymbol-mangling-version=legacy '--check-cfg=cfg(feature,values(any()))' -Zunstable-options -Zmacro-backtrace -Csplit-debuginfo=off -Cprefer-dynamic -Zinline-mir -Zinline-mir-preserve-debug -Zmir_strip_debuginfo=locals-in-tiny-functions -Clink-args=-Wl,-z,origin '-Clink-args=-Wl,-rpath,$ORIGIN/../lib' -Alinker-messages -Cembed-bitcode=yes -Clto=off -Zunstable-options -Cforce-frame-pointers=non-leaf '-Zcrate-attr=doc(html_root_url="https://doc.rust-lang.org/nightly/")' -Z binary-dep-depinfo` (exit status: 101) 

It works OK with rustc_codegen_llvm.

$ rustc -vV rustc 1.91.0-nightly (067965d6c 2025-10-27) (gentoo) binary: rustc commit-hash: 067965d6cc76bfd49637f46d05ae2111bbd2f121 commit-date: 2025-10-27 host: x86_64-unknown-linux-gnu release: 1.91.0-nightly 

This is with the rust 1.91.0 beta from 20251009 and github.com/rust-lang/rust from b93730ce97c738bdb9209aa973d3fc6fd4ce1d81.

Metadata

Metadata

Assignees

No one assigned

    Labels

    bugSomething isn't working

    Type

    No type

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions