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1.98 beta regression: compiler stack overflow #160685

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#161024
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1.98 beta regression: compiler stack overflow#160685
#161024
Labels
A-resolveArea: Name/path resolution done by `rustc_resolve` specificallyA-visibilityArea: Visibility / privacyC-bugCategory: This is a bug.E-needs-bisectionCall for participation: This issue needs bisection: https://github.com/rust-lang/cargo-bisect-rustcI-crashIssue: The compiler crashes (SIGSEGV, SIGABRT, etc). Use I-ICE instead when the compiler panics.P-highHigh priorityS-has-mcveStatus: A Minimal Complete and Verifiable Example has been found for this issueT-compilerRelevant to the compiler team, which will review and decide on the PR/issue.regression-from-stable-to-betaPerformance or correctness regression from stable to beta.
Milestone
1.98.0

Description

@theemathas
theemathas
opened on Aug 7, 2026

This regression was found by the 1.98 --release crater run in #159230

[INFO] [stderr] error: rustc interrupted by SIGSEGV, printing backtrace
[INFO] [stderr] 
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.98.0-beta.6-x86_64-unknown-linux-gnu/lib/librustc_driver-b53851df8ed457aa.so(+0x3ab521c) [0x71125f0b521c]
[INFO] [stderr] /usr/lib/x86_64-linux-gnu/libc.so.6(+0x45cb0) [0x71125b424cb0]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.98.0-beta.6-x86_64-unknown-linux-gnu/lib/librustc_driver-b53851df8ed457aa.so(+0x590d398) [0x711260f0d398]
[INFO] [stderr] 
[INFO] [stderr] ### cycle encountered after 3 frames with period 4
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.98.0-beta.6-x86_64-unknown-linux-gnu/lib/librustc_driver-b53851df8ed457aa.so(+0x590f21f) [0x711260f0f21f]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.98.0-beta.6-x86_64-unknown-linux-gnu/lib/librustc_driver-b53851df8ed457aa.so(+0x590f21f) [0x711260f0f21f]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.98.0-beta.6-x86_64-unknown-linux-gnu/lib/librustc_driver-b53851df8ed457aa.so(+0x590f21f) [0x711260f0f21f]
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.98.0-beta.6-x86_64-unknown-linux-gnu/lib/librustc_driver-b53851df8ed457aa.so(+0x590f21f) [0x711260f0f21f]
[INFO] [stderr] ### recursed 63 times
[INFO] [stderr] 
[INFO] [stderr] /opt/rustwide/rustup-home/toolchains/1.98.0-beta.6-x86_64-unknown-linux-gnu/lib/librustc_driver-b53851df8ed457aa.so(+0x590f21f) [0x711260f0f21f]
[INFO] [stderr] 
[INFO] [stderr] note: rustc unexpectedly overflowed its stack! this is a bug
[INFO] [stderr] note: maximum backtrace depth reached, frames may have been lost
[INFO] [stderr] note: we would appreciate a report at https://github.com/rust-lang/rust
[INFO] [stderr] help: you can increase rustc's stack size by setting RUST_MIN_STACK=16777216
[INFO] [stderr] error: could not compile `reflect_tools` (lib)

Reproducible with cargo +beta --release on a crate with reflect_tools = "0.4.0" as its only dependency.

Activity

  1. theemathas
    added
    I-crashIssue: The compiler crashes (SIGSEGV, SIGABRT, etc). Use I-ICE instead when the compiler panics.
    T-compilerRelevant to the compiler team, which will review and decide on the PR/issue.
    regression-from-stable-to-betaPerformance or correctness regression from stable to beta.
    C-bugCategory: This is a bug.
    E-needs-bisectionCall for participation: This issue needs bisection: https://github.com/rust-lang/cargo-bisect-rustc
    E-needs-mcveCall for participation: This issue has a repro, but needs a Minimal Complete and Verifiable Example
    on Aug 7, 2026
  2. rustbot
    added
    needs-triageThis issue may need triage. Remove when done. See docs forge.rust-lang.org/release/issue-triaging
    I-prioritizeIssue needs a team member to assess the impact. Will be replaced by P-{low,medium,high,critical}
    on Aug 7, 2026
  3. theemathas
    added a parent issue on Aug 7, 2026

  4. theemathas commented on Aug 7, 2026

    @theemathas
    theemathas
    on Aug 7, 2026
    ContributorAuthor

    Oh, it also reproduces with cargo +beta check on a crate with reflect_tools = "0.4.0" as its only dependency.

  5. theemathas
    changed the title [-]1.98 beta regression: compiler stack overflow with `--release`[/-] [+]1.98 beta regression: compiler stack overflow[/+] on Aug 7, 2026

  6. theemathas commented on Aug 7, 2026

    @theemathas
    theemathas
    on Aug 7, 2026
    ContributorAuthor

    Minimized reproducer:

    pub mod axiomatic {
    use super::*; // not pub
    pub use own::*;

    pub mod own {
        pub use super::*;
        pub use orphan::*;
    }

    pub mod orphan {
        pub use super::private::CollectionDescriptor;
    }

    pub mod private {
        pub struct CollectionDescriptor;
    }
}

pub use axiomatic::orphan::*;

    cc @petrochenkov, since this seems like your kind of thing

    (I'm currently having networking issues that's preventing me from doing bisection myself, so I'd appreciate someone else doing it.)

  7. theemathas
    added
    A-resolveArea: Name/path resolution done by `rustc_resolve` specifically
    S-has-mcveStatus: A Minimal Complete and Verifiable Example has been found for this issue
    and removed
    E-needs-mcveCall for participation: This issue has a repro, but needs a Minimal Complete and Verifiable Example
    needs-triageThis issue may need triage. Remove when done. See docs forge.rust-lang.org/release/issue-triaging
    on Aug 7, 2026

  8. theemathas commented on Aug 7, 2026

    @theemathas
    theemathas
    on Aug 7, 2026
    ContributorAuthor

    Note: The author of this crate is the same as the crate previously affected by #157406. This author appears to really like convoluted module setups.

  9. theemathas
    added
    A-visibilityArea: Visibility / privacy
    on Aug 7, 2026

  10. theemathas commented on Aug 7, 2026

    @theemathas
    theemathas
    on Aug 7, 2026
    ContributorAuthor

    Stack trace on MacOS:

    error: rustc interrupted by SIGBUS, printing backtrace

0   librustc_driver-01842c09d75be324.dy 0x00000001065c6fdc _RNvNtCslPNyqe8Oa6D_17rustc_driver_impl14signal_handler17print_stack_trace + 140
1   libsystem_platform.dylib            0x00000001820eb744 _sigtramp + 56
2   librustc_driver-01842c09d75be324.dy 0x0000000107edd88c _RNvMs0_NtCs5QQ3wBA2Bg1_13rustc_resolve22effective_visibilitiesNtB5_28EffectiveVisibilitiesVisitor17update_decl_chain + 3348
3   librustc_driver-01842c09d75be324.dy 0x0000000107edd88c _RNvMs0_NtCs5QQ3wBA2Bg1_13rustc_resolve22effective_visibilitiesNtB5_28EffectiveVisibilitiesVisitor17update_decl_chain + 3348

### cycle encountered after 4 frames with period 5
0   librustc_driver-01842c09d75be324.dy 0x0000000107edd704 _RNvMs0_NtCs5QQ3wBA2Bg1_13rustc_resolve22effective_visibilitiesNtB5_28EffectiveVisibilitiesVisitor17update_decl_chain + 2956
1   librustc_driver-01842c09d75be324.dy 0x0000000107edd704 _RNvMs0_NtCs5QQ3wBA2Bg1_13rustc_resolve22effective_visibilitiesNtB5_28EffectiveVisibilitiesVisitor17update_decl_chain + 2956
2   librustc_driver-01842c09d75be324.dy 0x0000000107edd704 _RNvMs0_NtCs5QQ3wBA2Bg1_13rustc_resolve22effective_visibilitiesNtB5_28EffectiveVisibilitiesVisitor17update_decl_chain + 2956
3   librustc_driver-01842c09d75be324.dy 0x0000000107edd704 _RNvMs0_NtCs5QQ3wBA2Bg1_13rustc_resolve22effective_visibilitiesNtB5_28EffectiveVisibilitiesVisitor17update_decl_chain + 2956
4   librustc_driver-01842c09d75be324.dy 0x0000000107edd704 _RNvMs0_NtCs5QQ3wBA2Bg1_13rustc_resolve22effective_visibilitiesNtB5_28EffectiveVisibilitiesVisitor17update_decl_chain + 2956
### recursed 50 times

0   librustc_driver-01842c09d75be324.dy 0x0000000107edd704 _RNvMs0_NtCs5QQ3wBA2Bg1_13rustc_resolve22effective_visibilitiesNtB5_28EffectiveVisibilitiesVisitor17update_decl_chain + 2956
1   librustc_driver-01842c09d75be324.dy 0x0000000107edd704 _RNvMs0_NtCs5QQ3wBA2Bg1_13rustc_resolve22effective_visibilitiesNtB5_28EffectiveVisibilitiesVisitor17update_decl_chain + 2956

note: maximum backtrace depth reached, frames may have been lost
note: we would appreciate a report at https://github.com/rust-lang/rust
error: could not compile `reflect_tools` (lib)

    Seems like an infinite recursion at

    rust/compiler/rustc_resolve/src/effective_visibilities.rs

    Line 140 in 65bcac4

    fn update_decl_chain(&mut self, mut decl: Decl<'ra>, mut parent_id: ParentId<'ra>) {

    This function was last touched in #159039, so I'm guessing it probably regressed there. cc @calvinrp (author of that PR)

  11. theemathas commented on Aug 7, 2026

    @theemathas
    theemathas
    on Aug 7, 2026
    ContributorAuthor

    Someone else did the bisection of the reflect_tools crate and got this output:

    searched nightlies: from nightly-2026-05-22 to nightly-2026-08-07
    regressed nightly: nightly-2026-07-15
    searched commit range: daf2e5e...da80ed0
    regressed commit: da80ed0

    bisected with cargo-bisect-rustc v0.6.11

    Host triple: x86_64-unknown-linux-gnu
    Reproduce with:

    cargo bisect-rustc --start=1.97.0 -- check

    (Edit: Bisecting the minimal reproducer pointed to the same PR.)

    So, my guess that this regressed in #159039 seems correct. Note that this PR was backported to 1.98.0 in #159384.

  12. rustbot
    removed
    I-prioritizeIssue needs a team member to assess the impact. Will be replaced by P-{low,medium,high,critical}
    on Aug 11, 2026

  13. rustbot commented on Aug 11, 2026

    @rustbot
    rustbot
    on Aug 11, 2026
    Collaborator

    Assigning P-high (discussion on Zulip).

  14. rustbot
    added
    P-highHigh priority
    on Aug 11, 2026

  15. apiraino commented on Aug 12, 2026

    @apiraino
    apiraino
    on Aug 12, 2026
    Contributor

    also cc @calvinrp since author of #159039

  16. calvinrp commented on Aug 12, 2026

    @calvinrp
    calvinrp
    on Aug 12, 2026
    Contributor

    I submitted #159039. I think I might root cause identified. I'll see if I can come up with a solution.

  17. Mark-Simulacrum
    added this to the 1.98.0 milestone on Aug 14, 2026
  18. JonathanBrouwer
    added a commit that references this issue on Aug 18, 2026

    Rollup merge of rust-lang#161024 - calvinrp:fix/pub-visibility, r=pet…

    5868ef5
  19. rust-bors
    closed this as completedin 5868ef5on Aug 18, 2026
  20. rust-bors
    added a commit that references this issue on Aug 18, 2026

    Unrolled build for #161024

    bdc5bbf
  21. RalfJung
    added a commit that references this issue on Aug 19, 2026

    Rollup merge of #161024 - calvinrp:fix/pub-visibility, r=petrochenkov

    7fae79c
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    A-resolveArea: Name/path resolution done by `rustc_resolve` specificallyA-visibilityArea: Visibility / privacyC-bugCategory: This is a bug.E-needs-bisectionCall for participation: This issue needs bisection: https://github.com/rust-lang/cargo-bisect-rustcI-crashIssue: The compiler crashes (SIGSEGV, SIGABRT, etc). Use I-ICE instead when the compiler panics.P-highHigh priorityS-has-mcveStatus: A Minimal Complete and Verifiable Example has been found for this issueT-compilerRelevant to the compiler team, which will review and decide on the PR/issue.regression-from-stable-to-betaPerformance or correctness regression from stable to beta.

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