Make NodeHandle generic and generate .Handle members of is-guards for guarding node handles (sync and async) - #4887
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Wesley Wigham (weswigham) merged 4 commits intoAug 14, 2026
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…es (sync and async)
Wesley Wigham (weswigham)
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Jake Bailey (jakebailey)
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August 12, 2026 18:49
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Pull request overview
Adds generic node handles and generated handle-aware AST guards for async and sync APIs.
Changes:
- Makes
NodeHandle<T>resolve typed AST nodes. - Adds
.Handlevariants to generated AST guards. - Adds async and sync narrowing coverage.
Reviewed changes
Copilot reviewed 7 out of 8 changed files in this pull request and generated 5 comments.
Show a summary per file
| File | Description |
|---|---|
_scripts/generate-ts-ast.ts |
Generates handle-aware guards. |
_packages/native-preview/src/ast/is.generated.ts |
Contains generated .Handle guards. |
_packages/native-preview/src/api/async/api.ts |
Adds generic async handles. |
_packages/native-preview/src/api/sync/api.ts |
Adds generated generic sync handles. |
_packages/native-preview/src/api/async/types.ts |
Types index declarations. |
_packages/native-preview/src/api/sync/types.ts |
Mirrors typed index declarations. |
_packages/native-preview/test/async/api.test.ts |
Tests async narrowing. |
_packages/native-preview/test/sync/api.test.ts |
Tests sync narrowing. |
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| out.push(`} from "./ast.ts";`); | ||
| out.push(`import type { NodeHandle as AsyncNodeHandle } from "../api/async/api.ts";`); | ||
| out.push(`import type { NodeHandle as SyncNodeHandle } from "../api/sync/api.ts";`); | ||
| out.push(`type NodeHandleLike<out T extends Node> = { kind: SyntaxKind; resolve(...args: any): any; };`); |
Comment on lines
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| out.push(`${g.funcName}.Handle = <T extends NodeHandleLike<Node>>(node: T): node is SpecializeNodeHandle<T, ${g.typeName}> => {`); | ||
| out.push(...functionContent); | ||
| out.push(`}`) |
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I think this is a good suggestion
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Sure, which is why I made it in the OP - only drawback is we lose typechecking of the NodeHandle guard implementations, so it's on us to make sure the implementation is valid for the type.
Andrew Branch (andrewbranch)
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Aug 13, 2026
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I think I caused a merge conflict, sorry 🥴
Wesley Wigham (weswigham)
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from Andrew Branch (andrewbranch)
August 13, 2026 21:00
Wesley Wigham (weswigham)
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August 13, 2026 21:00
Andrew Branch (andrewbranch)
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Aug 14, 2026
Jake Bailey (jakebailey)
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Aug 14, 2026
…or guarding node handles (sync and async) (microsoft/typescript-go#4887)
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So you can, for example:
and narrow
sig.declaration.Note that I am duplicating the implementations for the
.Handletype guards, but we could writefunc.Handle = func as anyand it'd work just as well, if we'd prefer the brevity.