Lowering unnamed fields and anonymous adt #115367

frank-king · 2023-08-30T01:03:48Z

This implements #49804.

Goals:

lowering anonymous ADTs from AST to HIR
generating definitions of anonymous ADTs
uniqueness check of the unnamed fields
field projection of anonymous ADTs
#[repr(C)] check of the anonymous ADTs

Non-Goals (will be in the next PRs)

capturing generic params for the anonymous ADTs from the parent ADT
pattern matching of anonymous ADTs
structural expressions of anonymous ADTs
rustdoc support of anonymous ADTs

rustbot · 2023-08-30T01:03:56Z

r? @cjgillot

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compiler/rustc_ast_lowering/src/lib.rs

compiler/rustc_hir/src/definitions.rs

compiler/rustc_ast_lowering/src/lib.rs

compiler/rustc_trait_selection/src/traits/select/mod.rs

compiler/rustc_middle/src/ty/context.rs

compiler/rustc_hir_analysis/src/astconv/mod.rs

compiler/rustc_mir_dataflow/src/value_analysis.rs

compiler/rustc_trait_selection/src/solve/assembly/structural_traits.rs

Fix the `AssertBoundIsClone` error for anonymous adts.

- improve diagnostics of field uniqueness check and representation check - simplify the implementation of field uniqueness check - remove some useless codes and improvement neatness

davidtwco

I think this is good enough to merge as-is, we can refactor and make further improvements in follow-ups, but this is a big PR and it's going to be prone to conflicts so best to get this progress landed.

davidtwco · 2024-02-12T11:59:57Z

@bors r+ rollup=never

bors · 2024-02-12T12:00:00Z

📌 Commit 0dbd6e9 has been approved by davidtwco

It is now in the queue for this repository.

bors · 2024-02-12T14:51:18Z

⌛ Testing commit 0dbd6e9 with merge bdc1592...

bors · 2024-02-12T17:05:46Z

☀️ Test successful - checks-actions
Approved by: davidtwco
Pushing bdc1592 to master...

rust-timer · 2024-02-12T18:21:00Z

Finished benchmarking commit (bdc1592): comparison URL.

Overall result: ❌✅ regressions and improvements - ACTION NEEDED

Next Steps: If you can justify the regressions found in this perf run, please indicate this with @rustbot label: +perf-regression-triaged along with sufficient written justification. If you cannot justify the regressions please open an issue or create a new PR that fixes the regressions, add a comment linking to the newly created issue or PR, and then add the perf-regression-triaged label to this PR.

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

Instruction count

This is a highly reliable metric that was used to determine the overall result at the top of this comment.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	6.1%	[0.3%, 20.7%]	9
Improvements ✅ (primary)	-1.1%	[-1.1%, -1.1%]	1
Improvements ✅ (secondary)	-0.3%	[-0.3%, -0.3%]	1
All ❌✅ (primary)	-1.1%	[-1.1%, -1.1%]	1

Max RSS (memory usage)

Results

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)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-2.0%	[-2.0%, -2.0%]	1
Improvements ✅ (secondary)	-5.3%	[-5.3%, -5.3%]	1
All ❌✅ (primary)	-2.0%	[-2.0%, -2.0%]	1

Cycles

Results

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)	-	-	0
Regressions ❌ (secondary)	6.9%	[2.7%, 13.8%]	6
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.1%	[-3.2%, -3.1%]	3
All ❌✅ (primary)	-	-	0

Binary size

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

Bootstrap: 661.706s -> 662.09s (0.06%)
Artifact size: 308.30 MiB -> 308.34 MiB (0.01%)

Kobzol · 2024-02-13T07:58:36Z

There seems to be a big regression here on this benchmark, which has a struct with many fields.

Should this have affected performance of non-anonymous fields?

frank-king · 2024-02-13T08:15:02Z

The query find_field seems to be inefficient and affects FnCtxt::check_field for tuple fields as well.

Is this problem serious? I'm going to do some refactoring work on this query (to implement struct patterns and struct expressions of unnamed fields), but I'm afraid I won't have much time till next week.

Kobzol · 2024-02-13T08:19:08Z

It would be nice to improve it eventually, it's probably not that rare to have structs with many fields, e.g. generated by macros. But there's no immediate rush :)

Kobzol · 2024-02-13T08:19:58Z

Oh, I only now noticed that it's a tuple struct. Yeah, so tuple structs with many fields are probably quite rare. In any case, if you find any wins here in the future, that would be great!

frank-king · 2024-02-13T08:27:25Z

No problem, I'll look into this benchmark in the next step of implementation.

rustbot assigned cjgillot Aug 30, 2023