[16.2] Reject TypeScript >= 7.0 with an actionable error (mitigation for #95801) - #95837
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[16.2] Reject TypeScript >= 7.0 with an actionable error (mitigation for #95801)#95837lukesandberg wants to merge 2 commits into
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TypeScript 7's native compiler no longer ships the JavaScript compiler API
(`typescript/lib/typescript.js`) that Next.js loads via `require('typescript')`.
Loading it crashes the build worker with a silent SIGSEGV/SIGABRT and no
actionable message.
Two cases are handled:
- When TS7 is already installed, the missing API file makes it look like a
missing dependency. Check the resolved `typescript` package version up front
and throw a CompileError with guidance to install TypeScript 6 or upgrade
Next.js. This runs before the auto-install path (so we don't reinstall the
unsupported version) and before the crashing `require()`.
- When TypeScript is absent entirely, pin the auto-install to `typescript@^6.0.0`
via a new optional `install` specifier on MissingDependency, instead of
pulling `latest` (which is TS7).
Temporary mitigation for the 16.2.x line; an alternative to the experimental
TypeScript CLI backend backport.
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## Summary A minimal mitigation for the TypeScript 7 problem on the `15.5.x` line, ported from the `next-16-2` mitigation (#95837). TypeScript 7's native compiler no longer ships the JavaScript compiler API (`typescript/lib/typescript.js`) that Next.js loads via `require('typescript')`, so an installed TS7 produces surprising failures with no actionable message. This was reported against 16.2 in #95801. ## What it does - Because the missing compiler-API file makes an installed TS7 look like a *missing* dependency, `hasNecessaryDependencies` now also exposes the resolved `typescript/package.json` path. `verifyTypeScriptSetup` reads that version up front and, if it's `>= 7.0.0` (including prereleases — `7.0.0-beta`/`-rc`, nightly `7.0.0-dev.*`, via the `7.0.0-0` sentinel with `includePrerelease`), throws a `CompileError` with guidance to install TypeScript 6 or upgrade Next.js, before the `require()` runs. Unlike the 16.2 mitigation, no install-specifier change is needed here: the `15.5` line already pins TypeScript auto-installs via `getTypeScriptPackageSpec` (`typescript@5.8.2`) rather than pulling `latest`. Applies to both `next dev` and `next build`. ## Notes - This is the minimal fix for `15.5`; the full `experimental.useTypeScriptCli` backend (real TS7 support) is a separate, larger effort and was considered overkill for this stable line. - Related: `next-16-2` mitigation #95837, and full backport #95831. ## Verification - `pnpm --filter=next build` - Boundary verified against the compiled semver: `5.8.2` / `6.x` (incl. `6.0.0-beta`) are not rejected; `7.0.0-dev.*` / `7.0.0-beta` / `7.0.0-rc` / `7.0.0` / `7.0.2` are rejected. - Manual repro with `typescript@7` + `next@15.5`: `next build` and `CI=1 next build` exit non-zero with the actionable error instead of the opaque failure.
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Summary
A minimal mitigation for #95801, where
next build/next devcrash with a silentSIGSEGV/SIGABRTon the16.2.xline whentypescript@7is installed. TypeScript 7's native compiler no longer ships the JavaScript compiler API (typescript/lib/typescript.js) that Next.js loads viarequire('typescript'), so loading it kills the process with no actionable message.This is an alternative to the full backport in #95831. Rather than backporting the experimental TypeScript CLI backend (and its prerequisites), it makes the unsupported case fail cleanly. The two are mutually exclusive: ship this now for a quick, low-risk fix, or take #95831 for actual TS7 support via
experimental.useTypeScriptCli.What it does
typescriptpackage.jsonversion is checked up front. If it's>= 7.0.0, throw aCompileErrorwith guidance to install TypeScript 6 or upgrade Next.js. This runs before the auto-install path (so we don't reinstall the unsupported version) and before the crashingrequire().typescript@^6.0.0(via a new optionalinstallspecifier onMissingDependency) instead of pullinglatest, which is TS7.Applies to both
next devandnext build.Fixes
Fixes #95801
Verification
pnpm --filter=next buildtypescript@7.0.2project (seenext build(16.2.x, Turbopack) crashes with a silent SIGSEGV/SIGABRT when typescript@7 is installed andtypescript.ignoreBuildErrors: trueis set in CI — please backport the graceful error from canary #95801):next buildandCI=1 next buildnow exit non-zero with the actionable error and noSIGSEGV/SIGABRT, and no longer churn through a pointless reinstall of the unsupported version first.typescriptremoved from the project, the auto-install now pulls the v6 range and the build succeeds.