feat: enable erasableSyntaxOnly in TypeScript configs#440
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Patrick Lafrance (patricklafrance) merged 2 commits intoJun 11, 2026
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Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Pull request overview
This PR updates the shared TypeScript base config to enforce “erasure-only” TypeScript syntax by enabling erasableSyntaxOnly, ensuring consumers remain compatible with type-stripping runtimes/toolchains and preventing TS constructs that introduce runtime semantics.
Changes:
- Enable
"erasableSyntaxOnly": truein the core TypeScript config so all derived configs inherit it. - Add a major changeset documenting the breaking nature of the new enforcement and opt-out guidance.
Reviewed changes
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| File | Description |
|---|---|
| packages/typescript-configs/core.json | Enables erasableSyntaxOnly in the shared base compilerOptions, affecting all extended configs. |
| .changeset/brave-tigers-erase.md | Declares a major bump and documents the breaking behavior + migration/opt-out instructions. |
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…taxOnly Both packages intentionally use `export =` because browserslist and Stylelint load configs via require() and need `module.exports` to be the config object itself. Also refreshes the stale comments blaming esbuild output (these packages build with tsc now). Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Patrick Lafrance (patricklafrance)
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What
Adds
"erasableSyntaxOnly": truetopackages/typescript-configs/core.json— all variants (react,library,web-application,monorepo-workspace) inherit it.Why
Bans TypeScript syntax that compiles to runtime code:
enum, constructor parameter properties, valuenamespaces,import =aliases. Keeps consumers compatible with type-stripping runtimes (Node--experimental-strip-types) and erasure-only toolchains, and removes a class of TS-only runtime semantics. Already the working convention in wl-app — this gives it compiler enforcement org-wide.Breaking change
Consumers using
enum/ parameter properties / value namespaces /import =will get type errors on upgrade — hence the major changeset (happy to downgrade to minor if you'd rather treat it as a lint-tightening). Opt-out is one line in the consumer'stsconfig.json:"erasableSyntaxOnly": false.Verification
typescript ^6.0.3— no peer bump needed.tsgo) with the flag enabled.🤖 Generated with Claude Code