Repository navigation
Conversation
cknitt
added this pull request to stack #8907
October 18, 2026 18:28
Codecov Report❌ Patch coverage is
Additional details and impacted files@@ Coverage Diff @@
## master #8905 +/- ##
==========================================
- Coverage 81.21% 81.20% -0.01%
==========================================
Files 457 458 +1
Lines 63853 63933 +80
==========================================
+ Hits 51859 51918 +59
- Misses 11994 12015 +21
🚀 New features to boost your workflow:
|
cknitt
force-pushed
the
parsetree-spread
branch
from
October 18, 2026 18:31
63aa4cf to
aa5c53b
Compare
rescript
@rescript/belt
@rescript/darwin-arm64
@rescript/linux-arm64
@rescript/linux-x64
@rescript/runtime
@rescript/win32-x64
commit: |
|
Developer playground preview: https://rescript-lang.github.io/rescript/dev-playground/?version=pr-8905 |
Member
Author
|
@codex review |
Codex Review SummaryThis comment shows the latest Codex review activity on this pull request.
ℹ️ About Codex in GitHubYour team has set up Codex to review pull requests in this repo. Reviews are triggered when you
Codex reacts with 👀 while any review is running, comments if it has suggestions, and reacts with 👍 once all reviews finish with no findings. |
|
Codex Review: Didn't find any major issues. More of your lovely PRs please. Reviewed commit: ℹ️ About Codex in GitHubYour team has set up Codex to review pull requests in this repo. Reviews are triggered when you
If Codex has suggestions, it will comment; otherwise it will react with 👍. Codex can also answer questions or update the PR. Try commenting "@codex address that feedback". |
cknitt
force-pushed
the
parsetree-spread
branch
2 times, most recently
from
October 21, 2026 17:42
5c58e38 to
2e93ed3
Compare
Why:
The parser turned [a, ...b] and list{...a, b} into calls of
Primitive_array.spread and Primitive_list.spread marked with res.spread,
so the formatter had to rebuild the literal from the call and got it
wrong: spreads of literals were flattened, attributes on the literal
were dropped and an empty list spread printed as an empty element.
Pexp_spread keeps the items and spreads in source order, and the type
checker gives it a Texp_spread node. Translation emits new Parray_spread
and Plist_spread primitives that compile to the same runtime calls. A list
literal whose only spread is its tail stays a chain of ::. The parsetree
and CMT magic numbers are bumped.
AST modified (array literal with a spread):
Example:
let x = [1, ...ys]
Before (parse):
expression
Pexp_apply
expression
attribute "res.spread"
Pexp_ident "Primitive_array.spread"
[
<arg>
Nolabel
expression
Pexp_array
[
expression
Pexp_array
[
expression
Pexp_constant PConst_int (1,None)
]
expression
Pexp_ident "ys"
]
]
After (parse):
expression
Pexp_spread array
[
Pspread_item
expression
Pexp_constant PConst_int (1,None)
Pspread
expression
Pexp_ident "ys"
]
Typedtree added (Texp_spread):
Example:
let ys = [2]
let x = [1, ...ys]
After (typed):
expression
Texp_spread array
[
expression
Texp_array
[
expression
Texp_constant Const_int 1
]
expression
Texp_ident "ys/1001"
]
Format modified (literals with spreads):
Example:
let x = [...[1, 2], 3, ...[]]
let y = @attr list{...xs, ...list{}, 1}
Before (rescript):
let x = [1, 2, 3, ]
let y = list{...xs, , 1}
After (rescript):
let x = [...[1, 2], 3, ...[]]
let y = @attr list{...xs, ...list{}, 1}
Review: Why do the generated item groups have ghost locations? The v0 encoding has no marker on them, and the ghost flag tells a group of items from an array or list literal that is spread. A call built by a PPX with real locations decodes to spreads only, which concatenates the same values.
Review: Why does the typed node hold the concatenated parts rather than the elements? The parts are the arrays and cons chains the runtime call takes, so the items keep the errors of array and list literals and translation needs no list building of its own.
Area: syntax printer typechecker lambda codegen analysis reanalyze tests
Output: unchanged, tests/tests JS byte-identical after a rebuild; a
combinatorial harness of all item/spread sequences up to length 4 compiles
to identical JS with the old and new bsc
Formatting: changed spreads of array and list literals and attributes on
literals with spreads are kept; comments in list spreads stay in place
Formats: ast ResImpl01318/ResIntf01318, cmt Caml1999T048
PPX: unchanged wire: the v0 encoding is the res.spread call it was, decoded
back to Pexp_spread (ast-mapping fixture SpreadLiterals.res)
Editor: unchanged: pipe completion types the literal as the runtime call;
SpreadLiterals.res covers AST dump, hints, highlighting and completion
Tests: +tests/syntax_tests/data/ast-mapping/SpreadLiterals.res
+tests/analysis_tests/tests/src/SpreadLiterals.res
+tests/build_tests/super_errors/fixtures/array_spread_type_mismatch.res
+tests/build_tests/super_errors/fixtures/list_spread_type_mismatch.res
+tests/build_tests/super_errors/fixtures/array_spread_annotation_mismatch.res
~tests/ounit_tests/ounit_ast_mapper0_tests.ml
~tests/syntax_tests/data/printer/expr/array.res
~tests/syntax_tests/data/printer/expr/list.res
~tests/syntax_tests/data/printer/comments/array.res
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EUpL6dKCiSwAeriDGRHqNr
Claude-Session: https://claude.ai/code/session_01Kr4cjoUi2f5VpMvE6wT9bo
Signed-off-by: Christoph Knittel <ck@cca.io>
cknitt
force-pushed
the
parsetree-spread
branch
from
October 21, 2026 18:03
2e93ed3 to
798978d
Compare
Member
Author
|
@codex review |
![chatgpt-codex-connector[bot]](https://avatars.githubusercontent.com/in/1144995?s=60&v=4){kind=small}
There was a problem hiding this comment.
💡 Codex Review
Here are some automated review suggestions for this pull request.
Reviewed commit: 798978d3ad
ℹ️ About Codex in GitHub
Your team has set up Codex to review pull requests in this repo. Reviews are triggered when you
- Open a pull request for review
- Mark a draft as ready
- Comment "@codex review".
If Codex has suggestions, it will comment; otherwise it will react with 👍.
Codex can also answer questions or update the PR. Try commenting "@codex address that feedback".
Comment on lines
+1427
to
+1432
| | Texp_spread (kind, parts) -> | ||
| prim | ||
| ~primitive: | ||
| (match kind with | ||
| | Spread_array -> Parray_spread | ||
| | Spread_list -> Plist_spread) |
There was a problem hiding this comment.
This new lowering—especially the Plist_spread path—is covered only by parser, mapper, diagnostic, and analysis fixtures; no added test asserts the resulting Lambda shape or successfully executes generated JavaScript for a non-tail list spread. A wrong primitive, reordered part list, or runtime-call wiring regression could therefore pass the added tests. Add focused Lambda assertions and end-to-end cases for both spread kinds.
AGENTS.md reference: compiler/AGENTS.md:L14-L16
Useful? React with 👍 / 👎.
This was referenced Oct 22, 2026
This branch has not been deployed
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Part of #8624 (
res.spreaditem).The parser used to turn
[a, ...b]andlist{...a, b}into calls ofPrimitive_array.spread/Primitive_list.spreadwith ares.spreadattribute on the function. They are now aPexp_spread (kind, elements)node with items and spreads in source order, typed asTexp_spread, and translated to newParray_spread/Plist_spreadLambda primitives that compile to the same runtime calls. A list literal whose only spread is its tail (list{a, ...b}) stays a chain of::, as before.Effects
tests/testsrebuilds byte-identical, and every item/spread sequence up to length 4 (arrays and lists, top level and in functions) compiles to the same JS with the old and newbsc.[...[1, 2], 3, ...[]]printed as[1, 2, 3, ](invalid), andlist{...xs, ...list{}, 1}aslist{...xs, , 1}@attr [1, ...a]→[1, ...a])This has type: list<int>, but it's expected to have type: array<int>) instead of "This array item has type list…". With a type annotation, the mismatch is reported at the element, as for a plain array literal.to0emits the old call andfrom0decodes it back. The generated item groups get ghost locations, so a group of items can be told apart from a spread array/list literal, and the round trip is exact. A spread call built by a PPX with real locations decodes to spreads only, which concatenates the same values. Calls without the marker stay calls.ResImpl/ResIntfandcmtbumped. The new Lambda primitives come after the last constant constructor, asPdict_spreaddid.New tests
ast-mapping/SpreadLiterals.resand an ounit case for the v0 wire shape, the exact round trip, PPX-built calls and unmarked callssuper_errors:array_spread_type_mismatch,list_spread_type_mismatch,array_spread_annotation_mismatchSpreadLiterals.res(AST dump, hints, highlighting, pipe completion)A stacked follow-up will fix a formatter bug that predates this PR: a line comment inside a literal used as a
switch/if/try/loop operand moves on every reformat.🤖 Generated with Claude Code
https://claude.ai/code/session_01EUpL6dKCiSwAeriDGRHqNr