feat(type-info): add Pick and Omit type synthesis by minseong0324 · Pull Request #9874 · biomejs/biome

minseong0324 · 2026-04-09T00:52:42Z

I used Claude Code to assist with this implementation.

Summary

Addresses items from #9810: synthesizes Pick<T, K> and Omit<T, K> following the existing Record<K, V> pattern.

Resolves T, extracts string literal keys from K, and filters members accordingly. Falls back to generic instantiation when T or K can't be resolved.

Test Plan

Snapshot tests.

…ypes Skip synthesis when T resolves to Union/Intersection/Reference instead of producing an empty object. Also deduplicates the fallback path for unresolved K and T.

…action, add valid tests

changeset-bot · 2026-04-09T00:52:50Z

🦋 Changeset detected

Latest commit: 438a40b

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 13 packages

Name	Type
@biomejs/biome	Patch
@biomejs/cli-win32-x64	Patch
@biomejs/cli-win32-arm64	Patch
@biomejs/cli-darwin-x64	Patch
@biomejs/cli-darwin-arm64	Patch
@biomejs/cli-linux-x64	Patch
@biomejs/cli-linux-arm64	Patch
@biomejs/cli-linux-x64-musl	Patch
@biomejs/cli-linux-arm64-musl	Patch
@biomejs/wasm-web	Patch
@biomejs/wasm-bundler	Patch
@biomejs/wasm-nodejs	Patch
@biomejs/backend-jsonrpc	Patch

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codspeed-hq · 2026-04-09T01:07:25Z

Merging this PR will not alter performance

✅ 58 untouched benchmarks
⏩ 196 skipped benchmarks¹

_{Comparing minseong0324:feat/type-pick-omit-synthesis (438a40b) with main (bcd6508)}

196 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

coderabbitai · 2026-04-09T01:08:34Z

Walkthrough

Adds Pick/Omit-aware resolution to the type resolver: when a TypeReferenceQualifier is Pick<T, K> or Omit<T, K> with two type parameters, the resolver resolves T, extracts string-literal keys from K, and filters T’s own members (Pick keeps members matching keys; Omit removes matching keys and retains unnamed members). Falls back to prior behaviour if K can’t be extracted or T isn’t object-like. Adds is_pick/is_omit predicates and expands many analyzer tests to cover Pick/Omit cases.

Possibly related PRs

feat(lint): detect tuple widening and inferred unions in noMisleadingReturnType #9843: Extends the noMisleadingReturnType test coverage with Pick/Omit-based cases that exercise similar misleading-return scenarios.

Suggested reviewers

ematipico
dyc3

🚥 Pre-merge checks | ✅ 2

✅ Passed checks (2 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: adding Pick and Omit type synthesis to the type-info module.
Description check	✅ Passed	The description provides a clear summary of what was implemented, how it works, and references the related issue, directly corresponding to the changeset across multiple files.

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⚔️ Resolve merge conflicts

Resolve merge conflict in branch feat/type-pick-omit-synthesis

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ematipico

The synthesis of Pick and Omit has definitely repercussions on some of our type-aware lint rules. This means:

we should add more tests for the other lint rules (it seems to added tests for one already)
we must have a changeset, notably focused towards what the lint rules can do now

minseong0324 · 2026-04-11T18:26:35Z

The synthesis of Pick and Omit has definitely repercussions on some of our type-aware lint rules. This means:

we should add more tests for the other lint rules (it seems to added tests for one already)

we must have a changeset, notably focused towards what the lint rules can do now

@ematipico Added test cases for the 8 type-aware rules in c96f270, and the changeset in 61ac64d.

coderabbitai

🧹 Nitpick comments (1)

crates/biome_js_analyze/tests/specs/nursery/noUselessTypeConversion/invalid.ts (1)
58-67: Optional: add Omit parity for number/boolean too.

You already cover Pick for number/boolean; adding matching Omit variants would make regressions even harder to sneak in. Not required, just a tidy completeness win.
🤖 Prompt for AI Agents
Verify each finding against the current code and only fix it if needed.

In
`@crates/biome_js_analyze/tests/specs/nursery/noUselessTypeConversion/invalid.ts`
around lines 58 - 67, Add matching Omit test cases for the number and boolean
cases to mirror the existing Pick variants: declare an omittedNum using Omit<{
n: number; s: string }, "s"> and call Number(omittedNum.n) and reference
omittedNum.n (mirroring pickedNum), and declare an omittedFlag using Omit<{
flag: boolean; label: string }, "label"> and call Boolean(omittedFlag.flag) and
use !!omittedFlag.flag (mirroring pickedBool); place these next to the existing
omittedStr / pickedNum / pickedBool blocks so the number/boolean Omit parity is
covered.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In
`@crates/biome_js_analyze/tests/specs/nursery/noUselessTypeConversion/invalid.ts`:
- Around line 58-67: Add matching Omit test cases for the number and boolean
cases to mirror the existing Pick variants: declare an omittedNum using Omit<{
n: number; s: string }, "s"> and call Number(omittedNum.n) and reference
omittedNum.n (mirroring pickedNum), and declare an omittedFlag using Omit<{
flag: boolean; label: string }, "label"> and call Boolean(omittedFlag.flag) and
use !!omittedFlag.flag (mirroring pickedBool); place these next to the existing
omittedStr / pickedNum / pickedBool blocks so the number/boolean Omit parity is
covered.

ℹ️ Review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 09bf57e and af11c8a.

⛔ Files ignored due to path filters (8)

crates/biome_js_analyze/tests/specs/nursery/noFloatingPromises/invalid.ts.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/nursery/noMisusedPromises/checksConditionalsInvalid.ts.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/nursery/noUnnecessaryConditions/invalid.ts.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/nursery/noUnsafePlusOperands/invalid.ts.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/nursery/noUselessTypeConversion/invalid.ts.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/nursery/useArraySortCompare/invalid.ts.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/nursery/useExhaustiveSwitchCases/invalid.ts.snap is excluded by !**/*.snap and included by **
crates/biome_js_analyze/tests/specs/nursery/useNullishCoalescing/invalid.ts.snap is excluded by !**/*.snap and included by **

📒 Files selected for processing (10)

.changeset/smooth-ideas-write.md
crates/biome_js_analyze/tests/specs/nursery/noFloatingPromises/invalid.ts
crates/biome_js_analyze/tests/specs/nursery/noMisusedPromises/checksConditionalsInvalid.ts
crates/biome_js_analyze/tests/specs/nursery/noUnnecessaryConditions/invalid.ts
crates/biome_js_analyze/tests/specs/nursery/noUnsafePlusOperands/invalid.ts
crates/biome_js_analyze/tests/specs/nursery/noUselessTypeConversion/invalid.ts
crates/biome_js_analyze/tests/specs/nursery/useArraySortCompare/invalid.ts
crates/biome_js_analyze/tests/specs/nursery/useExhaustiveSwitchCases/invalid.ts
crates/biome_js_analyze/tests/specs/nursery/useNullishCoalescing/invalid.ts
crates/biome_js_type_info/src/resolver.rs

✅ Files skipped from review due to trivial changes (1)

.changeset/smooth-ideas-write.md

ematipico

Thank you! Need to fix the merge conflicts

ematipico · 2026-04-12T10:06:25Z

+            let mut names = Vec::new();
+            for ty in union.types() {
+                let resolved = resolver.resolve_and_get(ty)?;
+                let TypeData::Literal(lit) = resolved.to_data() else {
+                    return None;
+                };
+                let Literal::String(s) = lit.as_ref() else {
+                    return None;
+                };
+                names.push(s.as_ref().clone());
+            }


I think this can be a written using types().filter_map().collect()

Done in f215a04. Used .iter() before filter_map since types() returns a slice.

coderabbitai

Actionable comments posted: 2

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@crates/biome_js_type_info/src/resolver.rs`:
- Around line 845-850: When synthesising Pick/Omit objects you're currently
hardcoding prototype: None in the TypeData::Object creation (inside the
resolver.register_and_resolve call); instead fetch and preserve the original
object's prototype value and use it when creating the new Object so prototype
metadata isn't lost. Locate where members is derived and the original
TypeData/Object instance for T, extract its prototype (e.g.
original_object.prototype or similar) and pass that value into the new Object's
prototype field rather than None; keep using members.into() for members and
ensure any Clone or ownership adjustments are handled.
- Around line 967-982: The current TypeData::Union arm uses filter_map which
silently drops non-string members and returns Some(vec) even if some union
members are invalid; change the logic in the TypeData::Union branch (the block
that calls resolver.resolve_and_get for each ty) to fail the whole operation
when any union member is not a Literal::String: iterate over union.types(), call
resolver.resolve_and_get(ty) for each, check that resolved.to_data() matches
TypeData::Literal and that lit is Literal::String, and if any check fails return
None; otherwise collect the string values into a Vec and return Some(vec).
Ensure you reference the same symbols (TypeData::Union,
resolver.resolve_and_get, TypeData::Literal, Literal::String) when applying the
fix.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

Push a commit to this branch (recommended)
Create a new PR with the fixes

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crates/biome_js_type_info/src/resolver.rs

coderabbitai · 2026-04-12T13:52:47Z

+                            if let Some(members) = members {
+                                let resolved_id: ResolvedTypeId = resolver.register_and_resolve(
+                                    TypeData::Object(Box::new(Object {
+                                        prototype: None,
+                                        members: members.into(),
+                                    })),


⚠️ Potential issue | 🟠 Major

Preserve the prototype when synthesising Pick/Omit objects

Line 848 hardcodes prototype: None. If T is an object with a prototype, that information is lost in the synthesised type.

Proposed fix

- if let Some(members) = members { + if let Some(members) = members { + let prototype = match &t_data { + TypeData::Object(object) => object.prototype.clone(), + _ => None, + }; let resolved_id: ResolvedTypeId = resolver.register_and_resolve( TypeData::Object(Box::new(Object { - prototype: None, + prototype, members: members.into(), })), );

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed. In `@crates/biome_js_type_info/src/resolver.rs` around lines 845 - 850, When synthesising Pick/Omit objects you're currently hardcoding prototype: None in the TypeData::Object creation (inside the resolver.register_and_resolve call); instead fetch and preserve the original object's prototype value and use it when creating the new Object so prototype metadata isn't lost. Locate where members is derived and the original TypeData/Object instance for T, extract its prototype (e.g. original_object.prototype or similar) and pass that value into the new Object's prototype field rather than None; keep using members.into() for members and ensure any Clone or ownership adjustments are handled.

…-synthesis # Conflicts: # crates/biome_js_analyze/tests/specs/nursery/noMisleadingReturnType/invalid.ts # crates/biome_js_analyze/tests/specs/nursery/noMisleadingReturnType/invalid.ts.snap # crates/biome_js_analyze/tests/specs/nursery/noMisleadingReturnType/valid.ts # crates/biome_js_analyze/tests/specs/nursery/noMisleadingReturnType/valid.ts.snap

…-synthesis

minseong0324 · 2026-04-13T12:51:32Z

Thank you! Need to fix the merge conflicts

@ematipico Resolved merge conflicts in 438a40b.

minseong0324 added 5 commits April 9, 2026 02:23

feat(type-info): add Pick and Omit type synthesis

fb3e8e1

test(lint): add Pick/Omit widening test cases

6a7ba3f

refactor(type-info): extract extract_string_literal_keys helper

356f862

refactor(type-info): guard Pick/Omit synthesis against non-object T t…

8f3bb2a

…ypes Skip synthesis when T resolves to Union/Intersection/Reference instead of producing an empty object. Also deduplicates the fallback path for unresolved K and T.

refactor(type-info): use Text instead of String in Pick/Omit key extr…

09bf57e

…action, add valid tests

github-actions Bot added A-Linter Area: linter L-JavaScript Language: JavaScript and super languages A-Type-Inference Area: type inference labels Apr 9, 2026

minseong0324 marked this pull request as ready for review April 9, 2026 01:04

Merge branch 'main' into feat/type-pick-omit-synthesis

b89b0d0

ematipico requested changes Apr 9, 2026

View reviewed changes

Comment thread crates/biome_js_type_info/src/resolver.rs

minseong0324 force-pushed the feat/type-pick-omit-synthesis branch 3 times, most recently from 1ec79bc to 38748cf Compare April 10, 2026 23:50

minseong0324 added 3 commits April 12, 2026 03:24

test(lint): add Pick/Omit synthesis cases for type-aware rules

c96f270

chore: add changesets

61ac64d

docs(type-info): document extract_string_literal_keys

af11c8a

minseong0324 force-pushed the feat/type-pick-omit-synthesis branch from 38748cf to af11c8a Compare April 11, 2026 18:25

minseong0324 requested a review from ematipico April 11, 2026 18:26

minseong0324 mentioned this pull request Apr 11, 2026

feat(type-info): add Partial, Required, and Readonly type synthesis #9875

Merged

coderabbitai Bot reviewed Apr 11, 2026

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ematipico reviewed Apr 12, 2026

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refactor(type-info): use iterator collect in extract_string_literal_keys

f215a04

minseong0324 force-pushed the feat/type-pick-omit-synthesis branch from 9321c99 to f215a04 Compare April 12, 2026 13:48

coderabbitai Bot reviewed Apr 12, 2026

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minseong0324 requested a review from ematipico April 12, 2026 14:45

github-actions Bot added the A-Project Area: project label Apr 13, 2026

Merge remote-tracking branch 'upstream/main' into feat/type-pick-omit…

438a40b

…-synthesis

minseong0324 force-pushed the feat/type-pick-omit-synthesis branch from 0939aa7 to 438a40b Compare April 13, 2026 12:42

ematipico approved these changes Apr 13, 2026

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ematipico merged commit 9e570d1 into biomejs:main Apr 13, 2026
18 checks passed

github-actions Bot mentioned this pull request Apr 13, 2026

ci: release #9890

Merged

coderabbitai Bot mentioned this pull request Apr 24, 2026

fix(lint/noUnnecessaryConditions): extend detection coverage #10108

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minseong0324 commented Apr 9, 2026

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Walkthrough

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