resolve: Cleanups and micro-optimizations to extern prelude #144746

petrochenkov · 2025-07-31T17:45:14Z

This is what can be done without changing the structure of ExternPreludeEntry, like in #144737.

See individual commits for details.

Do not write dummy bindings to extern prelude. Use more precise `Used::Scope` while recording use and remove now redundant `introduced_by_item` check.

rustbot · 2025-07-31T17:45:19Z

r? @davidtwco

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rustbot · 2025-07-31T17:45:21Z

These commits modify the Cargo.lock file. Unintentional changes to Cargo.lock can be introduced when switching branches and rebasing PRs.

If this was unintentional then you should revert the changes before this PR is merged.
Otherwise, you can ignore this comment.

petrochenkov · 2025-07-31T17:46:30Z

@bors2 try @rust-timer queue

rust-bors · 2025-07-31T17:46:34Z

⌛ Trying commit e58e6f8 with merge 29bbf36…

To cancel the try build, run the command @bors try cancel.

resolve: Cleanups and micro-optimizations to extern prelude

petrochenkov · 2025-07-31T17:49:17Z

compiler/rustc_resolve/src/late/diagnostics.rs

-                                        })
-                                    })
+                            names.extend(self.r.extern_prelude.keys().flat_map(|ident| {
+                                let res = Res::Def(DefKind::Mod, CRATE_DEF_ID.to_def_id());


Precise def id is not important here, there are a couple of other places in typo collection that do the same thing.

rust-bors · 2025-07-31T20:02:41Z

☀️ Try build successful (CI)
Build commit: 29bbf36 (29bbf3649bebe2a2b151e692e80c7d64ea8e7f68, parent: 3fb1b53a9dbfcdf37a4b67d35cde373316829930)

rust-timer · 2025-07-31T23:45:24Z

Finished benchmarking commit (29bbf36): comparison URL.

Overall result: no relevant changes - no action needed

Benchmarking this pull request means it may be perf-sensitive – we'll automatically label it not fit for rolling up. You can override this, but we strongly advise not to, due to possible changes in compiler perf.

@bors rollup=never
@rustbot label: -S-waiting-on-perf -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

Results (primary 2.3%, secondary 4.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.3%	[2.3%, 2.3%]	1
Regressions ❌ (secondary)	4.0%	[4.0%, 4.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.3%	[2.3%, 2.3%]	1

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

Results (secondary 0.0%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.0%	[0.0%, 0.0%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Bootstrap: 467.851s -> 468.994s (0.24%)
Artifact size: 376.84 MiB -> 376.80 MiB (-0.01%)

petrochenkov · 2025-08-01T07:25:41Z

No perf changes from removing double lookup is sort of good news, it means that re-introducing it when splitting extern prelude into two scopes (https://github.com/petrochenkov/rust/tree/extprel2, or https://github.com/petrochenkov/rust/tree/extprel3) will not regress it either.

@bors rollup=maybe

b-naber · 2025-08-02T11:56:16Z

@bors r+

bors · 2025-08-02T11:56:18Z

📌 Commit e58e6f8 has been approved by b-naber

It is now in the queue for this repository.

Rollup of 12 pull requests Successful merges: - #142205 (Mark `slice::swap_with_slice` unstably const) - #144188 (`available_parallelism`: Add documentation for why we don't look at `ulimit`) - #144322 (Add lint against dangling pointers from local variables) - #144497 (tests: Add test for basic line-by-line stepping in a debugger) - #144559 (Enable extract-insert-dyn.rs test on RISC-V (riscv64)) - #144667 (`AlignmentEnum` should just be `repr(usize)` now) - #144706 (Do not give function allocations alignment in consteval and Miri.) - #144746 (resolve: Cleanups and micro-optimizations to extern prelude) - #144785 (Regression test for LLVM error with unsupported expression in static initializer for const pointer in array on macOS.) - #144811 (Stylize `*-lynxos178-*` target maintainer handle to make it easier to copy/paste) - #144848 (For "stage 1" ui-fulldeps, use the stage 1 compiler to query target info) - #144853 (Remove unnecessary `rust_` prefixes) Failed merges: - #144794 (Port `#[coroutine]` to the new attribute system) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of #144746 - petrochenkov:extpreltidy, r=b-naber resolve: Cleanups and micro-optimizations to extern prelude This is what can be done without changing the structure of `ExternPreludeEntry`, like in #144737. See individual commits for details.

Rollup of 12 pull requests Successful merges: - rust-lang/rust#142205 (Mark `slice::swap_with_slice` unstably const) - rust-lang/rust#144188 (`available_parallelism`: Add documentation for why we don't look at `ulimit`) - rust-lang/rust#144322 (Add lint against dangling pointers from local variables) - rust-lang/rust#144497 (tests: Add test for basic line-by-line stepping in a debugger) - rust-lang/rust#144559 (Enable extract-insert-dyn.rs test on RISC-V (riscv64)) - rust-lang/rust#144667 (`AlignmentEnum` should just be `repr(usize)` now) - rust-lang/rust#144706 (Do not give function allocations alignment in consteval and Miri.) - rust-lang/rust#144746 (resolve: Cleanups and micro-optimizations to extern prelude) - rust-lang/rust#144785 (Regression test for LLVM error with unsupported expression in static initializer for const pointer in array on macOS.) - rust-lang/rust#144811 (Stylize `*-lynxos178-*` target maintainer handle to make it easier to copy/paste) - rust-lang/rust#144848 (For "stage 1" ui-fulldeps, use the stage 1 compiler to query target info) - rust-lang/rust#144853 (Remove unnecessary `rust_` prefixes) Failed merges: - rust-lang/rust#144794 (Port `#[coroutine]` to the new attribute system) r? `@ghost` `@rustbot` modify labels: rollup

petrochenkov added 4 commits July 31, 2025 19:20

resolve: Clarify extern prelude insertion for extern crate items

cde0374

resolve: Do not add erroneous names to extern prelude

2f7a2fa

resolve: Avoid double table lookup in extern_prelude_get

7309696

Do not write dummy bindings to extern prelude. Use more precise `Used::Scope` while recording use and remove now redundant `introduced_by_item` check.

resolve: Cleanup some uses of extern prelude in diagnostics

e58e6f8

rustbot assigned davidtwco Jul 31, 2025

rustbot added 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 Jul 31, 2025

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rust-bors bot added a commit that referenced this pull request Jul 31, 2025

Auto merge of #144746 - petrochenkov:extpreltidy, r=<try>

29bbf36

resolve: Cleanups and micro-optimizations to extern prelude

rustbot added the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 31, 2025

petrochenkov commented Jul 31, 2025

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petrochenkov mentioned this pull request Jul 31, 2025

[WIP] resolve: Better caching for unsuccessful crate resolutions #144737

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rustbot removed the S-waiting-on-perf Status: Waiting on a perf run to be completed. label Jul 31, 2025

petrochenkov mentioned this pull request Aug 1, 2025

resolve: Split extern prelude into two scopes #144793

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b-naber approved these changes Aug 2, 2025

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bors 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 Aug 2, 2025

Zalathar mentioned this pull request Aug 4, 2025

Rollup of 12 pull requests #144876

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bors merged commit 2105044 into rust-lang:master Aug 4, 2025
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rustbot added this to the 1.91.0 milestone Aug 4, 2025

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