resolve: fix effective visibilities for items in ambiguous glob sets#159039

calvinrp · 2026-07-09T21:22:09Z

Fixes #159038 (1.96.1 → 1.97.0 regression; details there).

When an item is glob-imported twice at different visibilities, effective visibility was computed from whichever declaration arrived first, not the most visible one. An exported item could then get no MIR encoded, and downstream crates fail with missing optimized MIR.

Fix: also walk the most visible declaration's re-export chain (update_decl_chain, recursing into ambiguity_vis_max). Lint behavior unchanged. Two regression tests added; tests/ui/{imports,privacy,resolve} pass with every #154149 / #156284 test unmodified.

@rustbot label +A-resolve +A-visibility +T-compiler +regression-from-stable-to-stable

rustbot · 2026-07-09T21:22:15Z

Thanks for the pull request, and welcome! The Rust Project is excited to review your changes, and you should hear from @petrochenkov (or someone else) some time within the next two weeks.

Please see the contribution instructions for more information. Namely, in order to ensure the minimum review times lag, PR authors and assigned reviewers should ensure that the review label (S-waiting-on-review and S-waiting-on-author) stays updated, invoking these commands when appropriate:

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Since PR 154149, when one item is glob-imported into a module twice with different visibilities, the first-arrived declaration stays in the resolution slot and the most visible declaration of the ambiguous glob set is only recorded in `ambiguity_vis_max`. `DeclData::vis()` returns the max, so name resolution, metadata reexports and `cross_crate_inlinable` export the item at the maximum visibility, but `set_bindings_effective_visibilities` walked only the slot-resident declaration's reexport chain. When the restricted route arrives first, the definition's effective visibility caps at the restricted visibility while the item is still exported: spurious dead_code, the item missing from reachable_set, should_encode_mir returning false, and downstream crates failing with "missing optimized MIR" (a 1.96.1 -> 1.97.0 stable-to-stable regression). Generalize the one-level `ambiguity_vis_max` update that PR 154149 added in `update_import` (to keep the most visible import from being reported as unused) into a walk of that declaration's whole reexport chain: extract the chain walk into `update_decl_chain` and recurse into `ambiguity_vis_max` at every hop, so the most visible declaration drives the effective visibility of everything on its route, including the final definition. Updates are monotone, so the dual walk is order-independent. The `ambiguous_import_visibilities` lint and the PR 156284 diagnostic suppression are untouched.

petrochenkov · 2026-07-10T12:02:36Z

We can do this, because effective visibilities are not precise and can be conservative.
As it's seen from the diff we previously updated a single ambiguity_vis_max import to "exported", but we need to do it with the whole import chain, and that is what this PR does.
@bors r+

rust-bors · 2026-07-10T12:02:40Z

📌 Commit 299a71d has been approved by petrochenkov

It is now in the queue for this repository.

@rustbot

…biguity, r=petrochenkov resolve: fix effective visibilities for items in ambiguous glob sets Fixes rust-lang#159038 (1.96.1 → 1.97.0 regression; details there). When an item is glob-imported twice at different visibilities, effective visibility was computed from whichever declaration arrived first, not the most visible one. An exported item could then get no MIR encoded, and downstream crates fail with ``missing optimized MIR``. Fix: also walk the most visible declaration's re-export chain (`update_decl_chain`, recursing into `ambiguity_vis_max`). Lint behavior unchanged. Two regression tests added; `tests/ui/{imports,privacy,resolve}` pass with every rust-lang#154149 / rust-lang#156284 test unmodified. @rustbot label +A-resolve +A-visibility +T-compiler +regression-from-stable-to-stable

@rustbot

…biguity, r=petrochenkov resolve: fix effective visibilities for items in ambiguous glob sets Fixes rust-lang#159038 (1.96.1 → 1.97.0 regression; details there). When an item is glob-imported twice at different visibilities, effective visibility was computed from whichever declaration arrived first, not the most visible one. An exported item could then get no MIR encoded, and downstream crates fail with ``missing optimized MIR``. Fix: also walk the most visible declaration's re-export chain (`update_decl_chain`, recursing into `ambiguity_vis_max`). Lint behavior unchanged. Two regression tests added; `tests/ui/{imports,privacy,resolve}` pass with every rust-lang#154149 / rust-lang#156284 test unmodified. @rustbot label +A-resolve +A-visibility +T-compiler +regression-from-stable-to-stable

…uwer Rollup of 10 pull requests Successful merges: - #157690 (codegen_ssa: pack small const aggregates into immediate stores) - #157706 (Deny `todo!()` in tidy) - #159005 (Use `as_lang_item` instead of repeatedly matching) - #156735 (Move NativeLib::filename to the rmeta-link archive member) - #159039 (resolve: fix effective visibilities for items in ambiguous glob sets) - #158930 (Reorganize `tests/ui/issues` [20/N]) - #158965 (Add codegen test for Result is_ok unwrap) - #158979 (Reorganize `tests/ui/issues` [21/N]) - #159050 (assert only opaques with sub unified hidden infer are non-rigid) - #159062 (Remove unused WEAK_ONLY_LANG_ITEMS static) Failed merges: - #158732 (Apply MCP 1003 and move diagnostics.rs into its own module)

@rustbot

…biguity, r=petrochenkov resolve: fix effective visibilities for items in ambiguous glob sets Fixes rust-lang#159038 (1.96.1 → 1.97.0 regression; details there). When an item is glob-imported twice at different visibilities, effective visibility was computed from whichever declaration arrived first, not the most visible one. An exported item could then get no MIR encoded, and downstream crates fail with ``missing optimized MIR``. Fix: also walk the most visible declaration's re-export chain (`update_decl_chain`, recursing into `ambiguity_vis_max`). Lint behavior unchanged. Two regression tests added; `tests/ui/{imports,privacy,resolve}` pass with every rust-lang#154149 / rust-lang#156284 test unmodified. @rustbot label +A-resolve +A-visibility +T-compiler +regression-from-stable-to-stable

rust-bors · 2026-07-13T18:28:06Z

💔 Test for 9cdbad9 failed: CI. Failed job:

auto - x86_64-gnu-llvm-21-3 (web logs, enhanced plaintext logs)

rust-log-analyzer · 2026-07-13T18:42:39Z

The job x86_64-gnu-llvm-21-3 failed! Check out the build log: (web) (plain enhanced) (plain)

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running 468 tests
##[error]The runner has received a shutdown signal. This can happen when the runner service is stopped, or a manually started runner is canceled.
..
Session terminated, killing shell......::group::Clock drift check
  local time: ..Mon Jul 13 18:27:20 UTC 2026
  network time: ...................................................Mon, 13 Jul 2026 18:27:20 GMT
.::endgroup::
............................ 87/468
.................................................. ...killed.
##[error]The operation was canceled.
Cleaning up orphan processes

JonathanBrouwer · 2026-07-13T18:54:37Z

@bors try jobs=x86_64-gnu-llvm-21-3
@bors retry

…<try> resolve: fix effective visibilities for items in ambiguous glob sets try-job: x86_64-gnu-llvm-21-3

rust-bors · 2026-07-13T20:53:49Z

☀️ Try build successful (CI)
Build commit: 1554fd0 (1554fd0a2c5b0b87b39fb5e249754632728f16ba)
Base parent: 225e91c (225e91c03da22cd4b9792b83c1cfc97967101614)

@rustbot

…biguity, r=petrochenkov resolve: fix effective visibilities for items in ambiguous glob sets Fixes rust-lang#159038 (1.96.1 → 1.97.0 regression; details there). When an item is glob-imported twice at different visibilities, effective visibility was computed from whichever declaration arrived first, not the most visible one. An exported item could then get no MIR encoded, and downstream crates fail with ``missing optimized MIR``. Fix: also walk the most visible declaration's re-export chain (`update_decl_chain`, recursing into `ambiguity_vis_max`). Lint behavior unchanged. Two regression tests added; `tests/ui/{imports,privacy,resolve}` pass with every rust-lang#154149 / rust-lang#156284 test unmodified. @rustbot label +A-resolve +A-visibility +T-compiler +regression-from-stable-to-stable

Rollup of 6 pull requests Successful merges: - #159039 (resolve: fix effective visibilities for items in ambiguous glob sets) - #156047 (Fix trait method resolution on an adjusted never type) - #159061 (Skip trivial cast lint for trait object upcasts) - #159241 (Update books) - #159248 (compiler: Remove `-Zmutable-noalias`) - #159250 (Rename `errors.rs` file to `diagnostics.rs` (13/N))

rust-bors · 2026-07-14T04:01:49Z

⌛ Testing commit 159b9a0 with merge efe31f2...

Workflow: https://github.com/rust-lang/rust/actions/runs/29304935407

@rustbot

…petrochenkov resolve: fix effective visibilities for items in ambiguous glob sets Fixes #159038 (1.96.1 → 1.97.0 regression; details there). When an item is glob-imported twice at different visibilities, effective visibility was computed from whichever declaration arrived first, not the most visible one. An exported item could then get no MIR encoded, and downstream crates fail with ``missing optimized MIR``. Fix: also walk the most visible declaration's re-export chain (`update_decl_chain`, recursing into `ambiguity_vis_max`). Lint behavior unchanged. Two regression tests added; `tests/ui/{imports,privacy,resolve}` pass with every #154149 / #156284 test unmodified. @rustbot label +A-resolve +A-visibility +T-compiler +regression-from-stable-to-stable

@rustbot

…biguity, r=petrochenkov resolve: fix effective visibilities for items in ambiguous glob sets Fixes rust-lang#159038 (1.96.1 → 1.97.0 regression; details there). When an item is glob-imported twice at different visibilities, effective visibility was computed from whichever declaration arrived first, not the most visible one. An exported item could then get no MIR encoded, and downstream crates fail with ``missing optimized MIR``. Fix: also walk the most visible declaration's re-export chain (`update_decl_chain`, recursing into `ambiguity_vis_max`). Lint behavior unchanged. Two regression tests added; `tests/ui/{imports,privacy,resolve}` pass with every rust-lang#154149 / rust-lang#156284 test unmodified. @rustbot label +A-resolve +A-visibility +T-compiler +regression-from-stable-to-stable

jhpratt · 2026-07-14T04:02:16Z

@bors yield

Yielding to encompassing rollup

rust-bors · 2026-07-14T04:02:20Z

Auto build was cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/29304935407

The next pull request likely to be tested is #159262.

Rollup of 6 pull requests Successful merges: - #159039 (resolve: fix effective visibilities for items in ambiguous glob sets) - #156047 (Fix trait method resolution on an adjusted never type) - #158981 (Fix where-bound suggestion with legacy const generics) - #159061 (Skip trivial cast lint for trait object upcasts) - #159248 (compiler: Remove `-Zmutable-noalias`) - #159250 (Rename `errors.rs` file to `diagnostics.rs` (13/N))

rust-bors · 2026-07-14T04:15:34Z

⌛ Testing commit 159b9a0 with merge 2354c2d...

Workflow: https://github.com/rust-lang/rust/actions/runs/29305537191

@rustbot

…petrochenkov resolve: fix effective visibilities for items in ambiguous glob sets Fixes #159038 (1.96.1 → 1.97.0 regression; details there). When an item is glob-imported twice at different visibilities, effective visibility was computed from whichever declaration arrived first, not the most visible one. An exported item could then get no MIR encoded, and downstream crates fail with ``missing optimized MIR``. Fix: also walk the most visible declaration's re-export chain (`update_decl_chain`, recursing into `ambiguity_vis_max`). Lint behavior unchanged. Two regression tests added; `tests/ui/{imports,privacy,resolve}` pass with every #154149 / #156284 test unmodified. @rustbot label +A-resolve +A-visibility +T-compiler +regression-from-stable-to-stable

jhpratt · 2026-07-14T04:15:56Z

again

@bors yield

rust-bors · 2026-07-14T04:15:59Z

Auto build was cancelled. Cancelled workflows:

https://github.com/rust-lang/rust/actions/runs/29305537191

The next pull request likely to be tested is #159263.

Rollup of 6 pull requests Successful merges: - #159039 (resolve: fix effective visibilities for items in ambiguous glob sets) - #158981 (Fix where-bound suggestion with legacy const generics) - #159061 (Skip trivial cast lint for trait object upcasts) - #159241 (Update books) - #159248 (compiler: Remove `-Zmutable-noalias`) - #159250 (Rename `errors.rs` file to `diagnostics.rs` (13/N))

@rustbot

Rollup merge of #159039 - calvinrp:fix/effective-vis-glob-ambiguity, r=petrochenkov resolve: fix effective visibilities for items in ambiguous glob sets Fixes #159038 (1.96.1 → 1.97.0 regression; details there). When an item is glob-imported twice at different visibilities, effective visibility was computed from whichever declaration arrived first, not the most visible one. An exported item could then get no MIR encoded, and downstream crates fail with ``missing optimized MIR``. Fix: also walk the most visible declaration's re-export chain (`update_decl_chain`, recursing into `ambiguity_vis_max`). Lint behavior unchanged. Two regression tests added; `tests/ui/{imports,privacy,resolve}` pass with every #154149 / #156284 test unmodified. @rustbot label +A-resolve +A-visibility +T-compiler +regression-from-stable-to-stable

[stable] 1.97.1 release This backports: * #159106 * #159047 Currently not approved: * #159039 - thread is trending towards a decline of backport

rustbot added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jul 9, 2026

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rustbot added A-resolve Area: Name/path resolution done by `rustc_resolve` specifically A-visibility Area: Visibility / privacy regression-from-stable-to-stable Performance or correctness regression from one stable version to another. labels Jul 9, 2026

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Regression 1.96.1 → 1.97.0: "missing optimized MIR" for pub fn glob-reexported alongside a restricted glob duplicate #159038

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calvinrp force-pushed the fix/effective-vis-glob-ambiguity branch from e84a2ff to 299a71d Compare July 9, 2026 21:24

theemathas removed regression-from-stable-to-stable Performance or correctness regression from one stable version to another. I-prioritize Issue needs a team member to assess the impact. Will be replaced by P-{low,medium,high,critical} labels Jul 9, 2026

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Rollup of 10 pull requests #159077

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Rollup of 10 pull requests #159080

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Rollup of 12 pull requests #159095

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rust-bors Bot pushed a commit that referenced this pull request Jul 13, 2026

Auto merge of #159039 - calvinrp:fix/effective-vis-glob-ambiguity, r=…

1554fd0

…<try> resolve: fix effective visibilities for items in ambiguous glob sets try-job: x86_64-gnu-llvm-21-3

rust-bors Bot added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 13, 2026

jhpratt mentioned this pull request Jul 14, 2026

Rollup of 6 pull requests #159260

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Rollup of 6 pull requests #159262

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jhpratt mentioned this pull request Jul 14, 2026

Rollup of 6 pull requests #159263

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rust-bors Bot merged commit 86ad394 into rust-lang:main Jul 14, 2026
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[stable] 1.97.1 release #159288

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