Enable verbatimModuleSyntax for @typespec/compiler [skip chg] - #11514
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timotheeguerin merged 4 commits intoJul 31, 2026
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Under verbatimModuleSyntax, tsc emits 'import { type X } from "mod"'
(all specifiers inline-type) as a bare side-effect 'import "mod"'. In
define-kit.ts this created a runtime edge define-kit -> program -> kits
that ran defineKit() before TypekitPrototype was initialized (TDZ).
Converting to 'import type { X }' fully erases the import, removing the
side-effect edges and fixing the cycle.
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Pull request overview
This PR completes the workspace rollout of TypeScript’s verbatimModuleSyntax by enabling it for @typespec/compiler and updating the compiler’s sources/tests to use explicit type-only imports/exports where appropriate, while preserving runtime side-effect imports needed for typekit registration.
Changes:
- Enable
verbatimModuleSyntax: trueforpackages/compilerviatsconfig.json. - Convert many type-only imports/exports across compiler source and tests to
import type/export typeto prevent unintended runtime imports/exports under verbatim module semantics. - Adjust selected barrels/exports (e.g., YAML/types, formatter print types, server exports) to avoid emitting value exports for type-only symbols.
Reviewed changes
Copilot reviewed 248 out of 248 changed files in this pull request and generated 2 comments.
Show a summary per file
| File | Description |
|---|---|
| packages/compiler/tsconfig.json | Enables verbatimModuleSyntax for the compiler package build. |
| packages/compiler/src/init/init-template-validate.ts | Type-only import conversion (needs a fix for typeof NoTarget with import type). |
| packages/compiler/src/lib/examples.ts | Type-only import conversion (needs a fix for typeof NoTarget with import type). |
| packages/compiler/src/index.ts | Converts several re-exports to export type to align with verbatim module semantics. |
| packages/compiler/src/config/index.ts | Converts config surface re-exports to export type where applicable. |
| packages/compiler/src/yaml/index.ts | Switches YAML types re-export to export type * to avoid runtime exports. |
| packages/compiler/src/server/serverlib.ts | Splits LSP imports into type vs value imports to preserve runtime constants. |
| .chronus/changes/type-import-pass-9-2026-7-31.md | Adds an internal changelog entry for the rollout. |
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You can try these changes here
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timotheeguerin
marked this pull request as ready for review
July 31, 2026 17:36
timotheeguerin
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RodgeFu,
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catalinaperalta,
iscai-msft,
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July 31, 2026 17:36
timotheeguerin
enabled auto-merge
July 31, 2026 17:36
timotheeguerin
changed the title
iscai-msft
approved these changes
Jul 31, 2026
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Part of the incremental rollout of TypeScript's
verbatimModuleSyntaxacross the workspace (batch 9, final).Enables
verbatimModuleSyntax: truefor@typespec/compiler— the last and largest of the core packages.Changes
"verbatimModuleSyntax": truetopackages/compiler/tsconfig.json(inherited bytsconfig.build.json).import type/export typeacross ~240 source and test files (via oxlint type-aware autofix).core/binder.tsandcore/checker.ts(SymbolTable,TypeInstantiationMap) were hand-split toimport type: each name is atypes.jsinterface that is shadowed by a local runtimeconst … = class …, which the autofixer conservatively skips.src/typekit/kits/index.tsas valueexport *. Thosekits/*modules rundefineKit(...)registration side effects at import time while only exporting type augmentations, so the autofixer'sexport type *would erase the modules and skip registration (the same trap fixed earlier for@typespec/http). Verified against the emitteddistthat all 17 kit namespaces still register at runtime.Validation
tsc -p tsconfig.build.json— 0 verbatim (TS1484/TS1205/TS1485) errors; full build (manifest, init-templates index, tsc, tmlanguage) passes.--type-aware --deny-warningsclean.tsp compileof a sample spec succeeds; a runtime check confirms all 17 typekit namespaces (enum,model,operation, …) are registered.Standalone runtime emitters (
http-client-csharp,http-client-java,http-client-python) remain out of scope, andtsconfig.base.jsonis intentionally untouched. This completes the workspace rollout.