Rust Engine: first resugaring by W95Psp · Pull Request #1528 · cryspen/hax

W95Psp · 2025-06-25T14:34:33Z

Description

This PR introduces improvements and extensions to the AST representation and printer logic in the Rust engine, particularly focusing on resugaring types.

Key Changes:

AST Structure:
- Modified Ty to publicly expose its inner box (pub Box<TyKind>).
- Renamed ResugaredTyKind to ResugaredItemKind within ItemKind::Resugared to match the intended semantics.
- Added a new variant Unit to ResugaredTyKind representing the unit type (()), differentiating it clearly from the empty tuple.
Resugaring Infrastructure:
- Defined a generic ResugaredFragment trait and implemented From conversions between resugared types and their parent fragments.
- Introduced a macro (derive_from!) to simplify repetitive trait implementations for AST fragment conversions.
Visitor Corrections:
- Updated visitor methods (visit_resugared_ty_kind → visit_resugared_item_kind) to reflect the accurate naming for ItemKind::Resugared variants, resolving naming inconsistencies across visitor implementations.
Printer Enhancements:
- Implemented Resugar and Printer traits for AST printing with resugaring phases.
- Added a generic Print trait with automatic implementations via macro (derive_print!) to simplify printing logic for various AST fragments.
- Introduced a common resugaring phase (UnitTyResugar) to convert zero-arity tuples into the dedicated unit type for clearer printing.
Allocator Improvements:
- Enhanced the Allocator constructor with a new convenience method (new) for improved ergonomics.

Testing:

Added unit tests for the new UnitTyResugar phase to ensure correct resugaring behavior.

Fixes #1580.

W95Psp · 2025-06-30T07:07:02Z

I just rebased on the base branch (this PR is part of a long PR chain)

jschneider-bensch

Looks good!
I just have some suggestions for documentation.

jschneider-bensch · 2025-07-01T06:12:50Z

rust-engine/src/ast/resugared.rs

+pub enum ResugaredTyKind {
+    /// The `unit` type.
+    ///
+    /// Without resugaring: a tuple of arity zero.


Does it make sense to document here which backend is expected to use a specific resugared node?

rust-engine/src/ast/resugared.rs

jschneider-bensch · 2025-07-01T06:43:18Z

rust-engine/src/ast/visitors/generated.rs

Not really part of this PR's scope, but I think it would be nice to reference codegen/README.md for details on how this module was generated in documentation at the top of this file.

jschneider-bensch · 2025-07-01T06:46:48Z

rust-engine/src/ast.rs

@@ -1465,7 +1465,7 @@ pub enum ItemKind {
    /// A resugared item.
    /// This variant is introduced before printing only.
    /// Phases must not produce this variant.


Suggested change

/// Phases must not produce this variant.

/// Backend phases must not produce this variant.

In the Printer documentation you also refer to "resugaring phases", so here it should be a bit more specific, no?

jschneider-bensch · 2025-07-01T06:54:39Z

rust-engine/src/printer.rs

+    fn print(self, fragment: &mut T) -> Option<(String, SourceMap)>;
+}
+
+macro_rules! derive_print {


Can you document what this macro does and if there is anything to know about how it implements Print? (e.g. I don't know what doc.render(80, ...) means and whether you'd want to know that this number means when you use the macro.

clementblaudeau

Looks good to me

clementblaudeau · 2025-07-02T09:33:15Z

rust-engine/src/ast/resugared.rs

 #[derive_group_for_ast]
 #[visitable]
-pub enum ResugaredTyKind {}
+pub enum ResugaredTyKind {


Maybe also add the empty tuple as a unit expression ? It feels like only having the type will not be usable by backends

…ent to their parent fragment

Co-authored-by: Jonas Schneider-Bensch <124457079+jschneider-bensch@users.noreply.github.com>

W95Psp · 2025-08-11T13:33:41Z

Closing in favor of #1528

W95Psp changed the base branch from main to rengine-visitors June 25, 2025 14:35

W95Psp force-pushed the rengine-first-resugaring branch from c47fcbe to 8bff6c0 Compare June 25, 2025 15:10

W95Psp marked this pull request as ready for review June 25, 2025 15:12

W95Psp requested a review from a team as a code owner June 25, 2025 15:12

W95Psp requested review from a team, clementblaudeau, jschneider-bensch and maximebuyse and removed request for a team and maximebuyse June 25, 2025 15:12

W95Psp force-pushed the rengine-visitors branch from 3ebe0a7 to 14e243c Compare June 30, 2025 06:44

W95Psp force-pushed the rengine-first-resugaring branch 2 times, most recently from cba9946 to bf655e9 Compare June 30, 2025 06:48

W95Psp force-pushed the rengine-visitors branch from 14e243c to bd0b1be Compare June 30, 2025 07:06

W95Psp force-pushed the rengine-first-resugaring branch from 1f3d8b8 to fbbea41 Compare June 30, 2025 07:06

clementblaudeau mentioned this pull request Jun 30, 2025

Lean backend [Part 1/3] #1509

Merged

4 tasks

W95Psp mentioned this pull request Jun 30, 2025

Rust Engine: intro. resugared AST fragment #1518

Merged

jschneider-bensch approved these changes Jul 1, 2025

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clementblaudeau approved these changes Jul 2, 2025

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W95Psp force-pushed the rengine-visitors branch from bd0b1be to 97362d0 Compare July 3, 2025 11:27

W95Psp force-pushed the rengine-visitors branch 3 times, most recently from 7cb712b to 7217c07 Compare July 24, 2025 09:46

W95Psp force-pushed the rengine-first-resugaring branch 4 times, most recently from ad80607 to d1a2f0f Compare July 24, 2025 10:08

W95Psp force-pushed the rengine-visitors branch from 69c0641 to 59da82a Compare July 24, 2025 12:11

W95Psp force-pushed the rengine-first-resugaring branch from d1a2f0f to 2bc7064 Compare July 24, 2025 12:13

W95Psp added 11 commits July 24, 2025 14:13

feat(rengine): add visitors for the AST

a148ff6

feat(rengine): add codegen for visitors

063712d

feat(rengine/visitors): make Sized optional, now Map is dyn compatible

59298b0

chore(rengine/visitors): regenerate

5930f1d

feat(rengine/codegen): refactor and add a new kind of visitor

ecb32e6

feat(rengine/ast): intro ErrorNode

33a8d8f

feat(rengine/ast/traits): add mut projections

c1e2a8f

feat(rengine/visitors): add flags to AST

363446a

chore: refresh generated visitors

c41633f

feat(rengine/visitors): add diagnostic handling visitors

11b6606

fix(rengine): minor

951050a

W95Psp force-pushed the rengine-visitors branch from 59da82a to 951050a Compare July 24, 2025 12:13

W95Psp and others added 6 commits July 24, 2025 14:13

fix(rengine/ast): make Ty payload public

1549e88

feat(rengine/ast/resugar): derive From instances from resugar fragm…

937af66

…ent to their parent fragment

feat(rengine): intro. resugaring traits, and one resugar

64bb9b5

chore(rengine/visitors): regenerate

59d1027

Update rust-engine/src/ast/resugared.rs

1901923

Co-authored-by: Jonas Schneider-Bensch <124457079+jschneider-bensch@users.noreply.github.com>

Update rust-engine/src/ast/resugared.rs

aaa8388

Co-authored-by: Jonas Schneider-Bensch <124457079+jschneider-bensch@users.noreply.github.com>

W95Psp force-pushed the rengine-first-resugaring branch from 2bc7064 to aaa8388 Compare July 24, 2025 12:14

W95Psp force-pushed the rengine-visitors branch 2 times, most recently from 24d88b5 to 0acc923 Compare July 24, 2025 12:22

W95Psp linked an issue Jul 24, 2025 that may be closed by this pull request

Rust Engine: add first resugaring #1580

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clementblaudeau closed this Aug 21, 2025

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Rust Engine: first resugaring#1528

Rust Engine: first resugaring#1528
W95Psp wants to merge 17 commits intorengine-visitorsfrom
rengine-first-resugaring

W95Psp commented Jun 25, 2025 •

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	/// Phases must not produce this variant.
	/// Backend phases must not produce this variant.

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Description

Key Changes:

Testing:

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W95Psp commented Jun 25, 2025 •

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