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Disable package.json conditional exports fallback lookups #62310

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Fixes #50762

@Copilot Copilot AI review requested due to automatic review settings August 20, 2025 22:26
@github-project-automation github-project-automation bot moved this to Not started in PR Backlog Aug 20, 2025
@typescript-bot typescript-bot added Author: Team For Milestone Bug PRs that fix a bug with a specific milestone labels Aug 20, 2025
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Pull Request Overview

This PR disables package.json conditional exports fallback lookups by modifying the module resolution logic to return immediately when a condition fails to resolve, preventing TypeScript from falling back to other conditions like 'types' when the primary condition ('import') doesn't find TypeScript declaration files.

Key changes:

  • Modified module resolution logic to stop searching after first failed condition
  • Updated test baselines to reflect the new resolution behavior where .mjs files are resolved directly instead of falling back to .d.ts files
  • Removed outdated comments describing the previous fallback behavior

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 2 comments.

File Description
src/compiler/moduleNameResolver.ts Added early return to prevent fallback condition searches
tests/cases/conformance/moduleResolution/conditionalExportsResolutionFallback.ts Removed comment describing old fallback behavior
tests/baselines/reference/*.trace.json Updated trace logs showing direct .mjs resolution instead of .d.ts fallback
tests/baselines/reference/*.errors.txt Removed comments about fallback behavior from error baselines

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@typescript-bot test top800

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Command Status Results
test top800 ✅ Started 👀 Results

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@andrewbranch Here are the results of running the top 800 repos with tsc comparing main and refs/pull/62310/merge:

Something interesting changed - please have a look.

Details

ahmedkhaleel2004/gitdiagram

tsconfig.json

  • error TS2307: Cannot find module 'geist/font/sans' or its corresponding type declarations.
  • error TS2322: Type '{ children: string; key: string; variant: string; className: string; onClick: (e: MouseEvent<HTMLButtonElement, MouseEvent>) => void; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS7016: Could not find a declaration file for module 'class-variance-authority'. '/mnt/ts_downloads/_/m/gitdiagram/node_modules/.pnpm/[email protected]/node_modules/class-variance-authority/dist/index.mjs' implicitly has an 'any' type.
  • error TS2339: Property 'variant' does not exist on type 'ButtonProps'.
  • error TS2339: Property 'size' does not exist on type 'ButtonProps'.

alan2207/bulletproof-react

apps/react-vite/tsconfig.json

anthropics/anthropic-quickstarts

financial-data-analyst/tsconfig.json

customer-support-agent/tsconfig.json

caorushizi/mediago

2 of 7 projects failed to build with the old tsc and were ignored

packages/renderer/tsconfig.json

captbaritone/webamp

4 of 7 projects failed to build with the old tsc and were ignored

examples/lazy/tsconfig.json

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@andrewbranch Here are some more interesting changes from running the top 800 repos suite

Details

coaidev/coai

app/tsconfig.json

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@andrewbranch Here are some more interesting changes from running the top 800 repos suite

Details

Dokploy/dokploy

2 of 6 projects failed to build with the old tsc and were ignored

packages/server/tsconfig.json

apps/dokploy/tsconfig.json

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@andrewbranch Here are some more interesting changes from running the top 800 repos suite

Details

facebook/lexical

6 of 16 projects failed to build with the old tsc and were ignored

examples/react-rich-collab/tsconfig.json

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@andrewbranch Here are some more interesting changes from running the top 800 repos suite

Details

getAsterisk/claudia

tsconfig.json

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@andrewbranch Here are some more interesting changes from running the top 800 repos suite

Details

github/docs

1 of 2 projects failed to build with the old tsc and were ignored

tsconfig.json

immutable-js/immutable-js

4 of 6 projects failed to build with the old tsc and were ignored

website/tsconfig.json

  • error TS7016: Could not find a declaration file for module '@jdeniau/immutable-devtools'. '/mnt/ts_downloads/_/m/immutable-js/node_modules/@jdeniau/immutable-devtools/dist/index.mjs' implicitly has an 'any' type.

inkonchain/ink-kit

tsconfig.json

ionic-team/ionicons

1 of 2 projects failed to build with the old tsc and were ignored

tsconfig.json

  • error TS2688: Cannot find type definition file for 'svgo'.
    • Project Scope

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@andrewbranch Here are some more interesting changes from running the top 800 repos suite

Details

karakeep-app/karakeep

apps/web/tsconfig.json

apps/mobile/tsconfig.json

apps/landing/tsconfig.json

apps/browser-extension/tsconfig.json

  • error TS2322: Type '{ children: Element; variant: string; onClick: () => void; className: string; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: Element; variant: string; size: string; onClick: () => void; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.

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@andrewbranch Here are some more interesting changes from running the top 800 repos suite

Details

Kilo-Org/kilocode

2 of 13 projects failed to build with the old tsc and were ignored

webview-ui/tsconfig.json

src/tsconfig.json

apps/web-roo-code/tsconfig.json

apps/web-evals/tsconfig.json

logto-io/logto

18 of 33 projects failed to build with the old tsc and were ignored

packages/demo-app/tsconfig.json

menloresearch/jan

7 of 10 projects failed to build with the old tsc and were ignored

docs/tsconfig.json

microsoft/vscode

7 of 61 projects failed to build with the old tsc and were ignored

extensions/github/tsconfig.json

mikro-orm/mikro-orm

15 of 37 projects failed to build with the old tsc and were ignored

tests/tsconfig.json

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@andrewbranch Here are some more interesting changes from running the top 800 repos suite

Details

miurla/morphic

tsconfig.json

  • error TS2322: Type '{ children: Element; type: "button"; variant: string; size: string; className: string; onClick: () => void; title: string; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: Element; variant: string; size: string; onClick: () => void; className: string; type: "button"; disabled: boolean; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: Element; type: "button" | "submit"; size: string; variant: string; className: string; disabled: boolean; onClick: (() => void) | undefined; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: Element; className: string; size: string; variant: string; onClick: () => void; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: string | Element; onClick: () => Promise<void>; disabled: boolean; size: string; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: string; onClick: () => void; disabled: boolean; size: string; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: string; variant: string; className: string; disabled: boolean; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: (string | Element)[]; key: number; variant: string; className: string; name: string; onClick: () => Promise<void>; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: (string | Element)[]; variant: string; size: string; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: Element; variant: string; size: string; onClick: () => void; "aria-label": string; tooltipContent: string; }' is not assignable to type 'IntrinsicAttributes & TooltipButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: string; variant: string; type: "button"; className: string; onClick: () => Promise<void>; disabled: boolean; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: Element; variant: string; size: string; onClick: () => Promise<void>; className: string; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: (string | Element)[]; variant: string; role: "combobox"; "aria-expanded": boolean; className: string; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: (string | Element)[]; type: "button"; variant: string; onClick: () => void; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: (string | Element)[]; className: string; variant: string; }' is not assignable to type 'IntrinsicAttributes & BadgeProps'.
  • error TS2322: Type '{ children: string; variant: string; className: string; type: "submit"; name: string; value: string; onClick: () => void; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: Element[]; className: string; type: "button"; variant: string; size: string; onClick: () => Promise<string | null | undefined>; "aria-label": string; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: (string | number)[]; variant: string; className: string; onClick: () => void; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: (string | ReactElement<any, string | JSXElementConstructor<any>>)[]; variant: string; className: string; }' is not assignable to type 'IntrinsicAttributes & BadgeProps'.
  • error TS2322: Type '{ children: (Element | ReactNode)[]; className: string | undefined; variant: string; }' is not assignable to type 'IntrinsicAttributes & BadgeProps'.
  • error TS7016: Could not find a declaration file for module 'class-variance-authority'. '/mnt/ts_downloads/_/m/morphic/node_modules/class-variance-authority/dist/index.mjs' implicitly has an 'any' type.
  • error TS2339: Property 'variant' does not exist on type 'BadgeProps'.
  • error TS2339: Property 'variant' does not exist on type 'ButtonProps'.
  • error TS2339: Property 'size' does not exist on type 'ButtonProps'.
  • error TS2339: Property 'variant' does not exist on type 'Omit<ButtonProps & RefAttributes<HTMLButtonElement>, "ref">'.
  • error TS2339: Property 'size' does not exist on type 'Omit<ButtonProps & RefAttributes<HTMLButtonElement>, "ref">'.
  • error TS2322: Type '{ children: Element[]; name?: string | undefined; value?: string | number | readonly string[] | undefined; prefix?: string | undefined; translate?: "yes" | "no" | undefined; content?: string | undefined; ... 285 more ...; className: string; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: Element[]; variant: string; className: string; onClick: () => void; size: string; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: Element[]; variant: string; size: string; className: string; onClick: () => void; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2339: Property 'side' does not exist on type 'SheetContentProps'.
  • error TS2322: Type '{ children: Element[]; "data-sidebar": string; "data-mobile": string; className: string; style: CSSProperties; side: "right" | "left"; }' is not assignable to type 'IntrinsicAttributes & SheetContentProps & RefAttributes<HTMLDivElement>'.
  • error TS2322: Type '{ children: Element[]; name?: string | undefined; value?: string | number | readonly string[] | undefined; prefix?: string | undefined; translate?: "yes" | "no" | undefined; content?: string | undefined; ... 286 more ...; onClick: (event: MouseEvent<...>) => void; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: Element; variant: string; className: string; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: string; variant: string; size: string; onClick: () => void; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: string; size: string; onClick: () => Promise<void>; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.
  • error TS2322: Type '{ children: Element; variant: string; size: string; className: string; onClick: (e: MouseEvent<HTMLButtonElement, MouseEvent>) => void; }' is not assignable to type 'IntrinsicAttributes & ButtonProps & RefAttributes<HTMLButtonElement>'.

musistudio/claude-code-router

2 of 3 projects failed to build with the old tsc and were ignored

ui/tsconfig.json

nextauthjs/next-auth

24 of 45 projects failed to build with the old tsc and were ignored

packages/adapter-xata/tsconfig.json

packages/adapter-surrealdb/tsconfig.json

nextjs/saas-starter

tsconfig.json

  • error TS7016: Could not find a declaration file for module 'class-variance-authority'. '/mnt/ts_downloads/_/m/saas-starter/node_modules/.pnpm/[email protected]/node_modules/class-variance-authority/dist/index.mjs' implicitly has an 'any' type.

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@andrewbranch Here are some more interesting changes from running the top 800 repos suite

Details

nhost/nhost

33 of 41 projects failed to build with the old tsc and were ignored

dashboard/tsconfig.test.json

dashboard/tsconfig.json

nitrojs/nitro

12 of 13 projects failed to build with the old tsc and were ignored

tsconfig.json

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@andrewbranch Here are some more interesting changes from running the top 800 repos suite

Details

octokit/octokit.js

tsconfig.json

  • error TS7016: Could not find a declaration file for module '@octokit/plugin-rest-endpoint-methods'. '/mnt/ts_downloads/_/m/octokit.js/node_modules/@octokit/plugin-rest-endpoint-methods/dist-src/index.js' implicitly has an 'any' type.

openstatusHQ/openstatus

11 of 27 projects failed to build with the old tsc and were ignored

apps/dashboard/tsconfig.json

Portkey-AI/gateway

1 of 2 projects failed to build with the old tsc and were ignored

cookbook/integrations/vercel/tsconfig.json

primefaces/primeng

apps/showcase/tsconfig.json

probot/probot

tsconfig.json

  • error TS7006: Parameter 'options' implicitly has an 'any' type.
  • error TS7006: Parameter 'file' implicitly has an 'any' type.
  • error TS7016: Could not find a declaration file for module '@octokit/plugin-rest-endpoint-methods'. '/mnt/ts_downloads/_/m/probot/node_modules/@octokit/plugin-rest-endpoint-methods/dist-src/index.js' implicitly has an 'any' type.

test/tsconfig.json

  • error TS7006: Parameter 'options' implicitly has an 'any' type.
  • error TS7006: Parameter 'file' implicitly has an 'any' type.
  • error TS7016: Could not find a declaration file for module '@octokit/plugin-rest-endpoint-methods'. '/mnt/ts_downloads/_/m/probot/node_modules/@octokit/plugin-rest-endpoint-methods/dist-src/index.js' implicitly has an 'any' type.

QwenLM/qwen-code

3 of 5 projects failed to build with the old tsc and were ignored

packages/vscode-ide-companion/tsconfig.json

  • error TS7016: Could not find a declaration file for module 'jsonrepair'. '/mnt/ts_downloads/_/m/qwen-code/node_modules/jsonrepair/lib/esm/index.js' implicitly has an 'any' type.

RSSNext/Folo

4 of 18 projects failed to build with the old tsc and were ignored

packages/internal/components/tsconfig.json

apps/mobile/web-app/html-renderer/tsconfig.json

  • error TS7016: Could not find a declaration file for module '@sentry/vite-plugin'. '/mnt/ts_downloads/_/m/Folo/node_modules/@sentry/vite-plugin/dist/esm/index.mjs' implicitly has an 'any' type.

ryoppippi/ccusage

1 of 2 projects failed to build with the old tsc and were ignored

tsconfig.json

shadcn-ui/ui

19 of 27 projects failed to build with the old tsc and were ignored

templates/monorepo-next/packages/ui/tsconfig.json

templates/monorepo-next/apps/web/tsconfig.json

steven-tey/novel

1 of 2 projects failed to build with the old tsc and were ignored

packages/headless/tsconfig.json

TanStack/query

78 of 118 projects failed to build with the old tsc and were ignored

packages/svelte-query-devtools/tsconfig.json

packages/solid-query-devtools/tsconfig.prod.json

packages/solid-query-devtools/tsconfig.json

packages/react-query-devtools/tsconfig.legacy.json

packages/react-query-devtools/tsconfig.json

packages/query-devtools/tsconfig.prod.json

packages/angular-query-persist-client/tsconfig.json

packages/angular-query-devtools-experimental/tsconfig.json

transloadit/uppy

20 of 62 projects failed to build with the old tsc and were ignored

packages/@uppy/companion/tsconfig.json

TypeCellOS/BlockNote

4 of 81 projects failed to build with the old tsc and were ignored

packages/server-util/tsconfig.json

packages/dev-scripts/tsconfig.json

web-infra-dev/midscene

7 of 14 projects failed to build with the old tsc and were ignored

packages/mcp/tsconfig.json

packages/android-playground/tsconfig.json

apps/report/tsconfig.json

apps/chrome-extension/tsconfig.json

apps/android-playground/tsconfig.json

webdriverio/webdriverio

28 of 49 projects failed to build with the old tsc and were ignored

packages/wdio-cucumber-framework/tsconfig.json

zaidmukaddam/scira

tsconfig.json

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This may well be more breaky than it's worth. We might just be stuck with this :/

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package.json exports resolution uses fallback conditions, unlike Node
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