Small refactorings in `need_type_info` module by WaffleLapkin · Pull Request #159002 · rust-lang/rust

WaffleLapkin · 2026-07-09T09:57:46Z

This supports low priority impl diagnostic.

There is only one place where `SourceKindSubdiag` is used without `SourceKindMultiSuggestion`; it doesn't seem useful to distinguish between them (I have no idea what either of the names means tbh)

rustbot · 2026-07-09T09:57:49Z

Some changes occurred in need_type_info.rs

cc @lcnr

lcnr · 2026-07-13T10:57:18Z

                };

-                if !have_turbofish {
+                let suggestion = have_turbofish.not().then(|| {


nit: would you be fine with just using an if else here

View changes since the review

I do prefer .then as imo it makes it more clearer when exactly is suggestion Some. That being said, an if is also fine, changed the code to use it.

lcnr · 2026-07-13T11:00:42Z

r=me after nit :>

This makes it clear that (what used to be called) `GenericLabel` and other generic variants are related -- the latter are suggestions, which can sometimes be present in *addition* to the label. Although this mainly helps future cleanups.

This simplifies things a bunch, as we don't need any mutable state to track subdiagnostics now. Also, this makes it clearer which diagnostics are possible.

WaffleLapkin · 2026-07-13T14:39:03Z

@bors r=lcnr

rust-bors · 2026-07-13T14:39:07Z

📌 Commit 4706067 has been approved by lcnr

It is now in the queue for this repository.

@lcnr

…ors, r=lcnr Small refactorings in `need_type_info` module r? @lcnr This supports low priority impl diagnostic.

…uwer Rollup of 13 pull requests Successful merges: - #159039 (resolve: fix effective visibilities for items in ambiguous glob sets) - #157706 (Deny `todo!()` in tidy) - #156712 (Pointer authentication config and user facing options) - #158535 (Support `#[track_caller]` on EII declarations) - #158632 (First steps of late-bound turbofishing (place FnDef behind a dummy binder)) - #159002 (Small refactorings in `need_type_info` module) - #159202 (Bump rustc-demangle to 0.1.28) - #159216 (Avoid using probe self_ty for delegation arguments) - #159222 (semicolon_in_expressions_from_macros: Lint on non-local macros too) - #156609 (Consider structurally impossible Sized predicates in MIR) - #158854 (Add `#[rustc_test_entrypoint_marker]`) - #158998 (Some minor ast validation and visiting cleanups) - #159123 (doc: clarify attr parser APIs)

@lcnr

…ors, r=lcnr Small refactorings in `need_type_info` module r? @lcnr This supports low priority impl diagnostic.

…uwer Rollup of 14 pull requests Successful merges: - #159039 (resolve: fix effective visibilities for items in ambiguous glob sets) - #157706 (Deny `todo!()` in tidy) - #158535 (Support `#[track_caller]` on EII declarations) - #158632 (First steps of late-bound turbofishing (place FnDef behind a dummy binder)) - #158846 (Fix unused variable warnings for diverging expressions) - #159002 (Small refactorings in `need_type_info` module) - #159202 (Bump rustc-demangle to 0.1.28) - #159216 (Avoid using probe self_ty for delegation arguments) - #159222 (semicolon_in_expressions_from_macros: Lint on non-local macros too) - #156609 (Consider structurally impossible Sized predicates in MIR) - #157993 (Expose more info about ADTs and functions in rustc_public) - #158854 (Add `#[rustc_test_entrypoint_marker]`) - #158998 (Some minor ast validation and visiting cleanups) - #159123 (doc: clarify attr parser APIs)

@lcnr

…ors, r=lcnr Small refactorings in `need_type_info` module r? @lcnr This supports low priority impl diagnostic.

…uwer Rollup of 15 pull requests Successful merges: - #159039 (resolve: fix effective visibilities for items in ambiguous glob sets) - #157706 (Deny `todo!()` in tidy) - #156047 (Fix trait method resolution on an adjusted never type) - #158535 (Support `#[track_caller]` on EII declarations) - #158632 (First steps of late-bound turbofishing (place FnDef behind a dummy binder)) - #158846 (Fix unused variable warnings for diverging expressions) - #159002 (Small refactorings in `need_type_info` module) - #159202 (Bump rustc-demangle to 0.1.28) - #159216 (Avoid using probe self_ty for delegation arguments) - #156609 (Consider structurally impossible Sized predicates in MIR) - #157993 (Expose more info about ADTs and functions in rustc_public) - #158804 (Clarify `as_uninit_mut` may point to uninitialized memory) - #158854 (Add `#[rustc_test_entrypoint_marker]`) - #158998 (Some minor ast validation and visiting cleanups) - #159123 (doc: clarify attr parser APIs)

…uwer Rollup of 13 pull requests Successful merges: - #157706 (Deny `todo!()` in tidy) - #158535 (Support `#[track_caller]` on EII declarations) - #158632 (First steps of late-bound turbofishing (place FnDef behind a dummy binder)) - #158846 (Fix unused variable warnings for diverging expressions) - #159002 (Small refactorings in `need_type_info` module) - #159202 (Bump rustc-demangle to 0.1.28) - #159216 (Avoid using probe self_ty for delegation arguments) - #156609 (Consider structurally impossible Sized predicates in MIR) - #157993 (Expose more info about ADTs and functions in rustc_public) - #158804 (Clarify `as_uninit_mut` may point to uninitialized memory) - #158854 (Add `#[rustc_test_entrypoint_marker]`) - #158998 (Some minor ast validation and visiting cleanups) - #159123 (doc: clarify attr parser APIs)

@lcnr

Rollup merge of #159002 - WaffleLapkin:need_type_info_refactors, r=lcnr Small refactorings in `need_type_info` module r? @lcnr This supports low priority impl diagnostic.

…uwer Rollup of 13 pull requests Successful merges: - rust-lang/rust#157706 (Deny `todo!()` in tidy) - rust-lang/rust#158535 (Support `#[track_caller]` on EII declarations) - rust-lang/rust#158632 (First steps of late-bound turbofishing (place FnDef behind a dummy binder)) - rust-lang/rust#158846 (Fix unused variable warnings for diverging expressions) - rust-lang/rust#159002 (Small refactorings in `need_type_info` module) - rust-lang/rust#159202 (Bump rustc-demangle to 0.1.28) - rust-lang/rust#159216 (Avoid using probe self_ty for delegation arguments) - rust-lang/rust#156609 (Consider structurally impossible Sized predicates in MIR) - rust-lang/rust#157993 (Expose more info about ADTs and functions in rustc_public) - rust-lang/rust#158804 (Clarify `as_uninit_mut` may point to uninitialized memory) - rust-lang/rust#158854 (Add `#[rustc_test_entrypoint_marker]`) - rust-lang/rust#158998 (Some minor ast validation and visiting cleanups) - rust-lang/rust#159123 (doc: clarify attr parser APIs)

Kobzol · 2026-07-21T07:47:37Z

@rust-timer build 3281f09

For #159246.

rust-timer · 2026-07-21T15:29:12Z

Finished benchmarking commit (3281f09): comparison URL.

Overall result: ✅ improvements - no action needed

Benchmarking means the PR may be perf-sensitive. It's automatically marked not fit for rolling up. Overriding is possible but disadvised: it risks changing compiler perf.

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

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-1.8%	[-2.5%, -0.5%]	14
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 2.6%, secondary -19.9%)

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

	mean	range	count
Regressions ❌ (primary)	2.6%	[2.6%, 2.6%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-19.9%	[-23.4%, -11.7%]	13
All ❌✅ (primary)	2.6%	[2.6%, 2.6%]	1

Cycles

Results (primary 2.6%, secondary -14.0%)

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

	mean	range	count
Regressions ❌ (primary)	2.6%	[2.6%, 2.6%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-14.0%	[-19.6%, -5.7%]	13
All ❌✅ (primary)	2.6%	[2.6%, 2.6%]	1

Binary size

This perf run didn't have relevant results for this metric.

Bootstrap: 488.117s -> 489.161s (0.21%)
Artifact size: 389.87 MiB -> 389.87 MiB (0.00%)

WaffleLapkin · 2026-07-21T17:51:55Z

The changes here are only on error path, so the perf change must be noise, right?

Kobzol · 2026-07-21T18:07:50Z

Yes, the serde-4threads benchmark was improved on all unrolled perf. builds from its containing rollup for some reason (not sure why). Nothing to see here, sorry!

WaffleLapkin added 2 commits July 9, 2026 11:52

split out suggestion generation for type hints into a separate function

fcb4680

merge SourceKindSubdiag and SourceKindMultiSuggestion

7517333

There is only one place where `SourceKindSubdiag` is used without `SourceKindMultiSuggestion`; it doesn't seem useful to distinguish between them (I have no idea what either of the names means tbh)

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 9, 2026

rustbot assigned lcnr Jul 9, 2026

WaffleLapkin mentioned this pull request Jul 9, 2026

Implement "low priority impls" #159003

Draft

lcnr reviewed Jul 13, 2026

View reviewed changes

WaffleLapkin force-pushed the need_type_info_refactors branch from 4b19bc6 to 2aa1ae4 Compare July 13, 2026 11:58

WaffleLapkin added 4 commits July 13, 2026 14:03

need type info: only allow 0-1 subdiagnostic

50d233d

This simplifies things a bunch, as we don't need any mutable state to track subdiagnostics now. Also, this makes it clearer which diagnostics are possible.

move TypeErrCtxt::suggesion to InferSourceKind

979a7e4

decouple InferSourceKind::suggesion from TypeErrCtxt

4706067

WaffleLapkin force-pushed the need_type_info_refactors branch from 2aa1ae4 to 4706067 Compare July 13, 2026 12:07

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

JonathanBrouwer mentioned this pull request Jul 13, 2026

Rollup of 13 pull requests #159231

Closed

JonathanBrouwer mentioned this pull request Jul 13, 2026

Rollup of 14 pull requests #159236

Closed

JonathanBrouwer mentioned this pull request Jul 13, 2026

Rollup of 15 pull requests #159240

Closed

JonathanBrouwer mentioned this pull request Jul 13, 2026

Rollup of 13 pull requests #159246

Merged

rust-bors Bot merged commit 3bd0126 into rust-lang:main Jul 13, 2026
13 checks passed

rustbot added this to the 1.99.0 milestone Jul 13, 2026

rust-timer added a commit that referenced this pull request Jul 13, 2026

Unrolled build for #159002

3281f09

Rollup merge of #159002 - WaffleLapkin:need_type_info_refactors, r=lcnr Small refactorings in `need_type_info` module r? @lcnr This supports low priority impl diagnostic.

WaffleLapkin deleted the need_type_info_refactors branch July 14, 2026 09:48

WaffleLapkin restored the need_type_info_refactors branch July 14, 2026 09:48

WaffleLapkin deleted the need_type_info_refactors branch July 14, 2026 09:50

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Small refactorings in `need_type_info` module#159002

Small refactorings in `need_type_info` module#159002
rust-bors[bot] merged 6 commits into
rust-lang:mainfrom
WaffleLapkin:need_type_info_refactors

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lcnr Jul 13, 2026 •

edited by rustbot

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Overall result: ✅ improvements - no action needed

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