Store `DefId` instead of `EiiDecl` in `EiiImplResolution::Known` by cezarbbb · Pull Request #158235 · rust-lang/rust

cezarbbb · 2026-06-22T02:15:19Z

Fixes the FIXME(eii) about removing the extern target from the encoded decl.

Known(EiiDecl) serialized the same EiiDecl N+1 times per entry (once as the declaration, once per Known impl). Changing to Known(DefId) eliminates that redundancy — the EiiDecl is recoverable via tcx.externally_implementable_items() or a local lookup map, consistent with how Rust metadata uses DefId as a reference elsewhere.

I believe there are benefits in both performance and size(full EiiDecl to single DefId, and O(N) to O(1) lookup).

Also fixes a soundness gap(I think?) in check_attr.rs where the Known branch skipped impl_unsafe checking, and replaces an .expect() in codegen_attrs.rs with a let Some pattern.

tracking issues: #125418

r? @jdonszelmann

rustbot · 2026-06-22T02:15:22Z

Some changes occurred in compiler/rustc_passes/src/check_attr.rs

cc @jdonszelmann, @JonathanBrouwer

Some changes occurred in compiler/rustc_hir/src/attrs

cc @jdonszelmann, @JonathanBrouwer

rustbot · 2026-06-22T02:15:24Z

jdonszelmann is currently at their maximum review capacity.
They may take a while to respond.

rustbot · 2026-07-06T02:50:53Z

This PR was rebased onto a different main commit. Here's a range-diff highlighting what actually changed.

Rebasing is a normal part of keeping PRs up to date, so no action is needed—this note is just to help reviewers.

bjorn3 · 2026-07-08T14:15:06Z

r? bjorn3

cezarbbb · 2026-07-09T02:53:31Z

You should be able to simplify this a bit further:

Applied. After this PR the Known branch only reads target.foreign_item, so impl_unsafe/name in the stored EiiDecl are dead. Slimming it to Option<Path> cleans that up. (impl_unsafe in generate_default_impl is still consumed by the impl_safety line, so that one stays.)

bjorn3 · 2026-07-14T12:35:13Z

@bors r+

rust-bors · 2026-07-14T12:35:17Z

📌 Commit 48a980d has been approved by bjorn3

It is now in the queue for this repository.

@jdonszelmann

Store `DefId` instead of `EiiDecl` in `EiiImplResolution::Known` Fixes the `FIXME(eii)` about removing the extern target from the encoded decl. `Known(EiiDecl)` serialized the same `EiiDecl` N+1 times per entry (once as the declaration, once per Known impl). Changing to `Known(DefId)` eliminates that redundancy — the `EiiDecl` is recoverable via `tcx.externally_implementable_items()` or a local lookup map, consistent with how Rust metadata uses `DefId` as a reference elsewhere. I believe there are benefits in both performance and size(full `EiiDecl` to single `DefId`, and O(N) to O(1) lookup). Also fixes a soundness gap(I think?) in `check_attr.rs` where the `Known` branch skipped `impl_unsafe` checking, and replaces an `.expect()` in `codegen_attrs.rs` with `a let Some` pattern. tracking issues: rust-lang#125418 r? @jdonszelmann

…uwer Rollup of 22 pull requests Successful merges: - #156047 (Fix trait method resolution on an adjusted never type) - #157824 (Comptime inherent impls) - #158235 (Store `DefId` instead of `EiiDecl` in `EiiImplResolution::Known`) - #158723 (Support EII on Windows MSVC) - #158993 (rerun in original typing mode if we meet any opaques in post analysis) - #159160 (Make `HasTokens` a sub-trait of `HasAttrs`.) - #159183 (Introduce InstanceKind::LlvmIntrinsic) - #159251 (Bump rustc-perf submodule) - #155013 (Suggest the `[const] Destruct` bound for type parameters in const functions when missing) - #159155 (unstable book: Document `diagnostic_on_unknown` feature) - #159235 (Add regression test for #95719) - #159243 (inline Once wait and wait_force) - #159255 (Replace shortened type with `_` instead of `...` as placeholder) - #159259 (Add regression test for #144033) - #159265 (bootstrap: skip intrinsic-test when rustfmt is unavailable) - #159269 (disable range-len-try-from.rs on s390x) - #159272 (slice: make swap delegate to swap_unchecked) - #159274 (bootstrap: Rename `std_crates_for_run_make` to `std_crates_for_make_run`) - #159275 (remove obsolete comment) - #159277 (Construct `tokens` for attrs made by `mk_attr_word` and other variants) - #159283 (Remove obsolete verbose flag from deref/ref suggestions) - #159290 (rustc-dev-guide subtree update)

@jdonszelmann

Rollup merge of #158235 - cezarbbb:eii-metadata-opt, r=bjorn3 Store `DefId` instead of `EiiDecl` in `EiiImplResolution::Known` Fixes the `FIXME(eii)` about removing the extern target from the encoded decl. `Known(EiiDecl)` serialized the same `EiiDecl` N+1 times per entry (once as the declaration, once per Known impl). Changing to `Known(DefId)` eliminates that redundancy — the `EiiDecl` is recoverable via `tcx.externally_implementable_items()` or a local lookup map, consistent with how Rust metadata uses `DefId` as a reference elsewhere. I believe there are benefits in both performance and size(full `EiiDecl` to single `DefId`, and O(N) to O(1) lookup). Also fixes a soundness gap(I think?) in `check_attr.rs` where the `Known` branch skipped `impl_unsafe` checking, and replaces an `.expect()` in `codegen_attrs.rs` with `a let Some` pattern. tracking issues: #125418 r? @jdonszelmann

…uwer Rollup of 22 pull requests Successful merges: - rust-lang/rust#156047 (Fix trait method resolution on an adjusted never type) - rust-lang/rust#157824 (Comptime inherent impls) - rust-lang/rust#158235 (Store `DefId` instead of `EiiDecl` in `EiiImplResolution::Known`) - rust-lang/rust#158723 (Support EII on Windows MSVC) - rust-lang/rust#158993 (rerun in original typing mode if we meet any opaques in post analysis) - rust-lang/rust#159160 (Make `HasTokens` a sub-trait of `HasAttrs`.) - rust-lang/rust#159183 (Introduce InstanceKind::LlvmIntrinsic) - rust-lang/rust#159251 (Bump rustc-perf submodule) - rust-lang/rust#155013 (Suggest the `[const] Destruct` bound for type parameters in const functions when missing) - rust-lang/rust#159155 (unstable book: Document `diagnostic_on_unknown` feature) - rust-lang/rust#159235 (Add regression test for rust-lang/rust#95719) - rust-lang/rust#159243 (inline Once wait and wait_force) - rust-lang/rust#159255 (Replace shortened type with `_` instead of `...` as placeholder) - rust-lang/rust#159259 (Add regression test for rust-lang/rust#144033) - rust-lang/rust#159265 (bootstrap: skip intrinsic-test when rustfmt is unavailable) - rust-lang/rust#159269 (disable range-len-try-from.rs on s390x) - rust-lang/rust#159272 (slice: make swap delegate to swap_unchecked) - rust-lang/rust#159274 (bootstrap: Rename `std_crates_for_run_make` to `std_crates_for_make_run`) - rust-lang/rust#159275 (remove obsolete comment) - rust-lang/rust#159277 (Construct `tokens` for attrs made by `mk_attr_word` and other variants) - rust-lang/rust#159283 (Remove obsolete verbose flag from deref/ref suggestions) - rust-lang/rust#159290 (rustc-dev-guide subtree update)

rustbot added A-attributes Area: Attributes (`#[…]`, `#![…]`) S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. labels Jun 22, 2026

rustbot assigned jdonszelmann Jun 22, 2026

bjorn3 reviewed Jun 22, 2026
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Comment threadcompiler/rustc_metadata/src/eii.rs Outdated

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Comment threadcompiler/rustc_codegen_ssa/src/codegen_attrs.rs Outdated

cezarbbb force-pushed the eii-metadata-opt branch from ddb4f2a to 499975bCompare June 23, 2026 01:33

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Comment threadcompiler/rustc_ast_lowering/src/item.rs Outdated

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bjorn3 added the F-extern_item_impls `#![feature(extern_item_impls)]` label Jul 8, 2026

rustbot assigned bjorn3 and unassigned jdonszelmann Jul 8, 2026

cezarbbb force-pushed the eii-metadata-opt branch from c65973d to b645391Compare July 9, 2026 02:51

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Comment threadcompiler/rustc_hir/src/attrs/data_structures.rs Outdated

Store DefId instead of EiiDecl in EiiImplResolution::Known
48a980d

cezarbbb force-pushed the eii-metadata-opt branch from b645391 to 48a980dCompare July 14, 2026 12:32

rust-borsBot 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 14, 2026

This was referenced Jul 14, 2026
Rollup of 21 pull requests #159292
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Rollup of 22 pull requests #159293
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rust-borsBot merged commit 9f5052b into rust-lang:mainJul 15, 2026
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rustbot added this to the 1.99.0 milestone Jul 15, 2026

cezarbbb deleted the eii-metadata-opt branch July 15, 2026 03:37

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Store `DefId` instead of `EiiDecl` in `EiiImplResolution::Known` - #158235

Store `DefId` instead of `EiiDecl` in `EiiImplResolution::Known`#158235
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