[ICE]: slice index out of range in ArArchiveBuilder::build when linking large static archive
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C-bug
I-ICE
needs-triage
T-compiler
- Dominant language
- Rust
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Description
(Issue written by GLM5.1)
Code
No minimal repro available — the ICE occurs when compiling the v8 crate (v149.4.0 from crates.io) which links a large static library (librusty_v8.a, ~180 MB). The panic is in the archive building stage, not triggered by any specific source code.
Meta
rustc --version --verbose:
rustc 1.96.0 (ac68faa20 2026-05-25) (Fedora 1.96.0-1.fc44)
binary: rustc
commit-hash: ac68faa20c58cbccd01ee7208bf3b6e93a7d7f96
commit-date: 2026-05-25
host: x86_64-unknown-linux-gnu
release: 1.96.0
LLVM version: 22.1.6
Error output
thread 'rustc' panicked at compiler/rustc_codegen_ssa/src/back/archive.rs:486:29:
range end index 184748900 out of range for slice of length 182790542
error: the compiler unexpectedly panicked. This is a bug
note: rustc 1.96.0 (ac68faa20 2026-05-25) (Fedora 1.96.0-1.fc44) running on x86_64-unknown-linux-gnu
note: compiler flags: --crate-type lib -C opt-level=1 -C embed-bitcode=no -C debuginfo=2 -C debug-assertions=on
Backtrace
thread 'rustc' panicked at compiler/rustc_codegen_ssa/src/back/archive.rs:486:29:
range end index 184748900 out of range for slice of length 182790542
stack backtrace:
0: 0x7f0cc79654eb - <<std as core::fmt::Display>::fmt
1: 0x7f0cc70dfdaa - core::fmt::write
2: 0x7f0cc797f2f6 - <unknown>
3: 0x7f0cc793372c - <unknown>
4: 0x7f0cc795561e - std::panicking::default_hook
5: 0x7f0cc4659502 - <unknown>
6: 0x7f0cc7955852 - std::panicking::panic_with_hook
7: 0x7f0cc79337e8 - <unknown>
8: 0x7f0cc792a779 - <unknown>
9: 0x7f0cc793525d - __rustc::rust_begin_unwind
10: 0x7f0cc3e4a13c - core::panicking::panic_fmt
11: 0x7f0cc3e4a228 - core::slice::index::slice_index_fail
12: 0x7f0cc72b6917 - <unknown>
13: 0x7f0cc72eb29c - <ArArchiveBuilder as ArchiveBuilder>::build
14: 0x7f0cc72c2814 - rustc_codegen_ssa::back::link::link_binary
15: 0x7f0cc729eb62 - <LlvmCodegenBackend as CodegenBackend>::link
16: 0x7f0cc74b3162 - <rustc_interface::queries::Linker>::link
17: 0x7f0cc736fd98 - <unknown>
18: 0x7f0cc736c82b - <unknown>
19: 0x7f0cc7372362 - <unknown>
20: 0x7f0cc7962345 - <unknown>
21: 0x7f0cc3c79d19 - start_thread
22: 0x7f0cc3cfd64c - __clone3
23: 0x0 - <unknown>
query stack during panic:
end of query stack
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with compiler/rustc_codegen_ssa/src/back/archive.rs at line 486 and inspect ArArchiveBuilder::build, using the v8 crate's large librusty_v8.a archive to reproduce the panic. Trace why the requested slice range exceeds the archive length; done means compiling that large static archive without the compiler panic.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- compilers
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Quiet
- Clarity
- Needs clarification
- Newbie friendliness
- 42/100