`rustc_builtin_macros` cleanup, part 6 by cyrgani · Pull Request #163211 · rust-lang/rust

cyrgani · 2026-09-23T12:08:02Z

As the next step after #163080, this PR removes more unneeded complexity, including the "mini version of Ty" and the FieldInfo for discriminants.

r? @nnethercote

rustbot · 2026-09-23T12:08:06Z

Changes to the code generated for builtin derived traits.

cc @nnethercote

nnethercote

Mostly looks good. Just one question below.

Also, you are allowed to write commit messages with more than one line :) Sometimes it's helpful to include an extra sentence or two explaining what is going on, or why it's being done.

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nnethercote · 2026-09-23T13:28:36Z

-            .collect::<Vec<String>>();
+        let prefixes: &[&str] = match selflike_args.len() {
+            1 => &["__self"],
+            2 => &["__self", "__arg1"],


This is good. The old code seemed designed to be very generic and handle a wide variety of possible method signatures, when in practice they have only a few forms.

nnethercote · 2026-09-23T13:34:08Z

            .map(|prefix| {
                let pieces_iter =
                    struct_def.fields().iter().enumerate().map(|(i, struct_field)| {
-                        let sp = struct_field.span.with_ctxt(self.span.ctxt());


Why can the with_ctxt be removed?

make_pattern_ident creates an ident with span self.span, so it already has the correct context and with_span_pos doesn't look at sps context

nnethercote · 2026-09-23T13:39:30Z


    pub methods: SmallVec<[MethodDef<'a>; 1]>,

-    pub associated_types: SmallVec<[(Ident, Ty); 1]>,


nnethercote · 2026-09-23T22:17:01Z

r=me once tests are green.

@bors delegate=cyrgani

rust-bors · 2026-09-23T22:17:04Z

✌️ @cyrgani, you can now approve this pull request!

If @nnethercote told you to "r=me" after making some further change, then please make that change and post @bors r=nnethercote.

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cyrgani · 2026-09-24T05:42:25Z

@bors r=nnethercote

rust-bors · 2026-09-24T05:42:27Z

📌 Commit 2196ae3 has been approved by nnethercote

It is now in the queue for this repository.

…uwer Rollup of 14 pull requests Successful merges: - #162976 (fix quadratic naming of duplicate sidebar links) - #161275 (Refactor `core::cmp::{smallest, largest}` & add `mir-opt` test) - #163143 (cg_llvm: Use fewer FFI calls to check the target CPU's features) - #163188 (Adjust for Arm64EC name mangling when checking for exported symbols) - #163211 (`rustc_builtin_macros` cleanup, part 6) - #161386 (Don't merge distinct impl candidates) - #162942 (Remove `StashKey::AssociatedTypeSuggestion`) - #163096 (Don't suggest `std::` rustfix paths in `#![no_std]` crates) - #163110 (Mark `std::os::wasip2` with correct doc-cfgs, mark as unstable) - #163185 (properly decrement available_depth on cycles and provisional cache hits) - #163214 (revert r14 register names for arm) - #163226 (miri subtree update) - #163228 (Add regression test for trait predicate with escaping bounds) - #163234 (`rustc_dump_symbol_name`: add demangling information as a note instead)

@nnethercote

Rollup merge of #163211 - cyrgani:builtin-macros-6, r=nnethercote `rustc_builtin_macros` cleanup, part 6 As the next step after #163080, this PR removes more unneeded complexity, including the "mini version of `Ty`" and the `FieldInfo` for discriminants. r? @nnethercote

rust-timer · 2026-09-24T20:38:45Z

Note

This PR was benchmarked as part of triage of its containing rollup: triage URL.

Finished benchmarking commit (4e54401): comparison URL.

Overall result: ❌✅ regressions and improvements - please read:

Our benchmarks found a performance regression caused by this PR.
This might be an actual regression, but it can also be just noise.

Next Steps:

If the regression was expected or you think it can be justified,
please write a comment with sufficient written justification, and add
@rustbot label: +perf-regression-triaged to it, to mark the regression as triaged.
If you think that you know of a way to resolve the regression, try to create
a new PR with a fix for the regression.
If you do not understand the regression or you think that it is just noise,
you can ask the @rust-lang/wg-compiler-performance working group for help (members of this group
were already notified of this PR).

@rustbot label: +perf-regression
cc @rust-lang/wg-compiler-performance

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)	0.6%	[0.2%, 0.9%]	8
Regressions ❌ (secondary)	0.8%	[0.6%, 0.9%]	5
Improvements ✅ (primary)	-0.4%	[-0.5%, -0.3%]	12
Improvements ✅ (secondary)	-0.3%	[-0.3%, -0.3%]	1
All ❌✅ (primary)	-0.0%	[-0.5%, 0.9%]	20

Max RSS (memory usage)

Results (primary -0.6%, secondary -0.7%)

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
Improvements ✅ (primary)	-0.6%	[-0.6%, -0.6%]	2
Improvements ✅ (secondary)	-0.7%	[-0.7%, -0.7%]	1
All ❌✅ (primary)	-0.6%	[-0.6%, -0.6%]	2

Cycles

Results (secondary 2.9%)

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)	2.9%	[2.9%, 2.9%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: missing data
Artifact size: 406.30 MiB -> 406.25 MiB (-0.01%)

also apply late discriminant comparison optimization to derive(Ord)

51fa7ee

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 Sep 23, 2026

rustbot assigned nnethercote Sep 23, 2026

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merge Ord and PartialOrd code

ffb56b9

rust-cloud-vms Bot force-pushed the builtin-macros-6 branch from 544b651 to 5657ac1 Compare September 23, 2026 13:32

nnethercote reviewed Sep 23, 2026

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nnethercote added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 23, 2026

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cyrgani added 10 commits September 23, 2026 22:00

inline discriminant_value calls

976fcac

small stuff

921a20a

move helper methods away from TraitDef

42bc8af

inline expand_struct/enum_def

b5c30be

remove unused, untested associated_types

d736fe1

use Self instead of type_ident once more

327639d

add cx.expr_ident_sym

ec57172

remove the FieldInfo from EnumDiscr

839f431

simplify the rfold call

bf645be

remove the local version of Ty

2196ae3

rust-cloud-vms Bot force-pushed the builtin-macros-6 branch from 5657ac1 to 2196ae3 Compare September 23, 2026 22:01

nnethercote approved these changes Sep 23, 2026

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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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 24, 2026

JonathanBrouwer mentioned this pull request Sep 24, 2026

Rollup of 14 pull requests #163244

Merged

rust-bors Bot merged commit 3e13f47 into rust-lang:main Sep 24, 2026
13 checks passed

rustbot added this to the 1.100.0 milestone Sep 24, 2026

cyrgani deleted the builtin-macros-6 branch September 24, 2026 16:15

rustbot added the perf-regression Performance regression. label Sep 24, 2026

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`rustc_builtin_macros` cleanup, part 6 - #163211

`rustc_builtin_macros` cleanup, part 6#163211
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		pub methods: SmallVec<[MethodDef<'a>; 1]>,

		pub associated_types: SmallVec<[(Ident, Ty); 1]>,

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Overall result: ❌✅ regressions and improvements - please read:

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