Detect struct construction with private field in field with default #135846

estebank · 2025-01-21T21:35:41Z

When trying to construct a struct that has a public field of a private type, suggest using .. if that field has a default value.

error[E0603]: struct `Priv1` is private
  --> $DIR/non-exhaustive-ctor-2.rs:19:39
   |
LL |     let _ = S { field: (), field1: m::Priv1 {} };
   |                            ------     ^^^^^ private struct
   |                            |
   |                            while setting this field
   |
note: the struct `Priv1` is defined here
  --> $DIR/non-exhaustive-ctor-2.rs:14:4
   |
LL |    struct Priv1 {}
   |    ^^^^^^^^^^^^
help: the type `Priv1` of field `field1` is private, but you can construct the default value defined for it in `S` using `..` in the struct initializer expression
   |
LL |     let _ = S { field: (), .. };
   |                            ~~

rustbot · 2025-01-21T21:35:50Z

r? @fmease

rustbot has assigned @fmease.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

Use r? to explicitly pick a reviewer

tests/ui/structs/default-field-values/non-exhaustive-ctor-2.stderr

fmease

Preliminary review.

tests/ui/structs/default-field-values/non-exhaustive-ctor-2.stderr

fmease · 2025-01-25T18:30:57Z

compiler/rustc_resolve/src/lib.rs

@@ -1022,6 +1023,7 @@ pub struct Resolver<'ra, 'tcx> {

    /// N.B., this is used only for better diagnostics, not name resolution itself.
    field_names: LocalDefIdMap<Vec<Ident>>,
+    field_defaults: LocalDefIdMap<Vec<Symbol>>,


Using Symbol instead Ident raises a few warning flags in my head because I'm pretty sure that this means anything involving field_defaults doesn't handle macro hygiene correctly. This is only relevant to decl macros 2.0 (feature decl_macro).

It might be a non-issue, I haven't thought that hard yet. I'll need to read the rest of this PR first.

Worst case it's just wrong diagnostics in macro edge cases

compiler/rustc_middle/src/query/mod.rs

fmease · 2025-01-25T18:40:30Z

Checking perf due to additional query feeding in the happy path (if I saw that correctly).

@bors try @rust-timer queue

…r=<try> Detect struct construction with private field in field with default When trying to construct a struct that has a public field of a private type, suggest using `..` if that field has a default value. ``` error[E0603]: struct `Priv1` is private --> $DIR/non-exhaustive-ctor.rs:25:39 | LL | let _ = S { field: (), field1: m::Priv1 {} }; | ------ ^^^^^ private struct | | | while setting this field | note: the struct `Priv1` is defined here --> $DIR/non-exhaustive-ctor.rs:14:4 | LL | struct Priv1 {} | ^^^^^^^^^^^^ help: the field `field1` you're trying to set has a default value, you can use `..` to use it | LL | let _ = S { field: (), .. }; | ~~ ```

rust-timer · 2025-01-25T23:10:36Z

Finished benchmarking commit (5e87c8e): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

Benchmarking this pull request likely means that it is perf-sensitive, so we're automatically marking it as not fit for rolling up. While you can manually mark this PR as fit for rollup, we strongly recommend not doing so since this PR may lead to changes in compiler perf.

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

Instruction count

This is the most reliable metric that we have; it was used to determine the overall result at the top of this comment. However, even this metric can sometimes exhibit noise.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.8%	[0.8%, 0.8%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.3%	[-0.3%, -0.2%]	2
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 2.1%, secondary -0.1%)

This is a less reliable metric that may be of interest but was not used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	2.1%	[0.8%, 3.4%]	2
Regressions ❌ (secondary)	1.2%	[1.2%, 1.2%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.6%	[-0.6%, -0.6%]	3
All ❌✅ (primary)	2.1%	[0.8%, 3.4%]	2

Cycles

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

Binary size

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

Bootstrap: 770.579s -> 772.7s (0.28%)
Artifact size: 325.79 MiB -> 325.79 MiB (-0.00%)

bors · 2025-03-11T21:57:07Z

☔ The latest upstream changes (presumably #128440) made this pull request unmergeable. Please resolve the merge conflicts.

wesleywiser · 2025-04-17T14:30:17Z

Hi @fmease, I think this is just waiting on some feedback from you whether this is an issue or not and then a rebase from the author since perf looks neutral. Thanks!

bors · 2025-07-25T13:55:00Z

⌛ Testing commit c41fee3 with merge 21c50ce...

bors · 2025-07-25T15:22:57Z

💔 Test failed - checks-actions

estebank · 2025-07-25T19:18:06Z

I'm not quite sure how this PR affects https://github.com/rust-lang/rust/blob/75e9b19d78a601d07df4d8f19f72165026f32103/tests/debuginfo/lexical-scope-in-if-let.rs at all :(

bors · 2025-08-08T10:10:06Z

☔ The latest upstream changes (presumably #145077) made this pull request unmergeable. Please resolve the merge conflicts.

When trying to construct a struct that has a public field of a private type, suggest using `..` if that field has a default value. ``` error[E0603]: struct `Priv1` is private --> $DIR/non-exhaustive-ctor.rs:25:39 | LL | let _ = S { field: (), field1: m::Priv1 {} }; | ------ ^^^^^ private struct | | | while setting this field | note: the struct `Priv1` is defined here --> $DIR/non-exhaustive-ctor.rs:14:4 | LL | struct Priv1 {} | ^^^^^^^^^^^^ help: the field `field1` you're trying to set has a default value, you can use `..` to use it | LL | let _ = S { field: (), .. }; | ~~ ```

estebank · 2025-08-10T21:32:09Z

@bors r=BoxyUwU

bors · 2025-08-10T21:32:12Z

📌 Commit 29d26f2 has been approved by BoxyUwU

It is now in the queue for this repository.

…, r=BoxyUwU Detect struct construction with private field in field with default When trying to construct a struct that has a public field of a private type, suggest using `..` if that field has a default value. ``` error[E0603]: struct `Priv1` is private --> $DIR/non-exhaustive-ctor-2.rs:19:39 | LL | let _ = S { field: (), field1: m::Priv1 {} }; | ------ ^^^^^ private struct | | | while setting this field | note: the struct `Priv1` is defined here --> $DIR/non-exhaustive-ctor-2.rs:14:4 | LL | struct Priv1 {} | ^^^^^^^^^^^^ help: the type `Priv1` of field `field1` is private, but you can construct the default value defined for it in `S` using `..` in the struct initializer expression | LL | let _ = S { field: (), .. }; | ~~ ```

Rollup of 3 pull requests Successful merges: - #135846 (Detect struct construction with private field in field with default) - #144558 (Point at the `Fn()` or `FnMut()` bound that coerced a closure, which caused a move error) - #145149 (Make config method invoke inside parse use dwn_ctx) r? `@ghost` `@rustbot` modify labels: rollup

bors · 2025-08-10T23:47:28Z

⌛ Testing commit 29d26f2 with merge 21a19c2...

bors · 2025-08-11T02:58:07Z

☀️ Test successful - checks-actions
Approved by: BoxyUwU
Pushing 21a19c2 to master...

github-actions · 2025-08-11T03:01:12Z

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing c8ca44c (parent) -> 21a19c2 (this PR)

Test differences

Show 60 test diffs

Stage 1

[ui] tests/ui/structs/default-field-values/non-exhaustive-ctor-2.rs: [missing] -> pass (J0)

Stage 2

[ui] tests/ui/structs/default-field-values/non-exhaustive-ctor-2.rs: [missing] -> pass (J1)

Additionally, 58 doctest diffs were found. These are ignored, as they are noisy.

Job group index

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 21a19c297d4f5a03501d92ca251bd7a17073c08a --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

x86_64-apple-2: 3918.3s -> 6252.0s (59.6%)
dist-aarch64-linux: 8024.5s -> 5898.1s (-26.5%)
dist-x86_64-apple: 8566.4s -> 10684.1s (24.7%)
x86_64-apple-1: 9553.5s -> 7800.9s (-18.3%)
tidy: 115.1s -> 103.9s (-9.7%)
x86_64-gnu-llvm-20-1: 3430.3s -> 3721.1s (8.5%)
aarch64-apple: 6323.7s -> 5819.7s (-8.0%)
aarch64-gnu-llvm-19-2: 2633.4s -> 2439.7s (-7.4%)
x86_64-gnu-llvm-20-2: 6483.7s -> 6064.4s (-6.5%)
test-various: 5071.1s -> 4745.7s (-6.4%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

rust-timer · 2025-08-11T04:09:35Z

Finished benchmarking commit (21a19c2): comparison URL.

Overall result: ❌ regressions - no action needed

@rustbot label: -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)	0.3%	[0.3%, 0.3%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary 0.2%, secondary 0.4%)

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

	mean	range	count
Regressions ❌ (primary)	1.6%	[1.6%, 1.6%]	1
Regressions ❌ (secondary)	3.6%	[3.3%, 3.9%]	3
Improvements ✅ (primary)	-1.1%	[-1.1%, -1.1%]	1
Improvements ✅ (secondary)	-1.6%	[-2.7%, -1.0%]	5
All ❌✅ (primary)	0.2%	[-1.1%, 1.6%]	2

Cycles

Results (primary 2.5%, secondary 2.7%)

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

	mean	range	count
Regressions ❌ (primary)	2.5%	[2.5%, 2.5%]	1
Regressions ❌ (secondary)	2.7%	[2.4%, 2.9%]	2
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	2.5%	[2.5%, 2.5%]	1

Binary size

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

Bootstrap: 464.929s -> 464.264s (-0.14%)
Artifact size: 377.32 MiB -> 377.36 MiB (0.01%)

rustbot assigned fmease Jan 21, 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 Jan 21, 2025

estebank added F-default_field_values `#![feature(default_field_values)]` and removed T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jan 21, 2025

estebank mentioned this pull request Jan 21, 2025

Tracking issue for RFC 3681: Default field values #132162

Open

17 tasks

estebank added the T-compiler Relevant to the compiler team, which will review and decide on the PR/issue. label Jan 21, 2025

estebank mentioned this pull request Jan 21, 2025

Detect missing fields with default values and suggest .. #135794

Merged

estebank added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. A-diagnostics Area: Messages for errors, warnings, and lints labels Jan 22, 2025

jieyouxu reviewed Jan 22, 2025

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tests/ui/structs/default-field-values/non-exhaustive-ctor-2.stderr Outdated Show resolved Hide resolved

estebank force-pushed the non-exhaustive-dfv-ctor-2 branch 2 times, most recently from 5f24487 to 7e07e4f Compare January 23, 2025 05:35

fmease reviewed Jan 25, 2025

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estebank force-pushed the non-exhaustive-dfv-ctor-2 branch from 7e07e4f to 38f8f98 Compare January 28, 2025 07:35

estebank force-pushed the non-exhaustive-dfv-ctor-2 branch from 38f8f98 to 7d576f6 Compare February 12, 2025 00:18

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bors added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Jul 25, 2025

estebank force-pushed the non-exhaustive-dfv-ctor-2 branch from c41fee3 to 217048f Compare July 30, 2025 17:22

BoxyUwU 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 Aug 1, 2025

estebank added 2 commits August 10, 2025 19:15

review comments

29d26f2

estebank force-pushed the non-exhaustive-dfv-ctor-2 branch from 217048f to 29d26f2 Compare August 10, 2025 19:20

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-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Aug 10, 2025

samueltardieu mentioned this pull request Aug 10, 2025

Rollup of 3 pull requests #145231

Closed

bors added the merged-by-bors This PR was explicitly merged by bors. label Aug 11, 2025

bors merged commit 21a19c2 into rust-lang:master Aug 11, 2025
11 checks passed

rustbot added this to the 1.91.0 milestone Aug 11, 2025

This was referenced Aug 11, 2025

Handle macros with multiple kinds, and improve errors #145153

Merged

Implement declarative (macro_rules!) derive macros (RFC 3698) #145208

Draft

matthiaskrgr mentioned this pull request Aug 13, 2025

ICE: no entry found for key #145367

Open

Detect struct construction with private field in field with default #135846

Detect struct construction with private field in field with default #135846

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rust-timer commented Jan 25, 2025

Overall result: ❌✅ regressions and improvements - no action needed

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Test differences

Stage 1

Stage 2

Job duration changes

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rust-timer commented Aug 11, 2025

Overall result: ❌ regressions - no action needed

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