Summary

Fixes #62909

When using moduleResolution: "bundler" with wildcard exports patterns like "./*": "./src/*", extensionless imports (e.g., import from "@repo/library/utils") now correctly resolve to TypeScript files (e.g., ./src/utils.ts).

Problem

Previously, loadFileNameFromPackageJsonField would return undefined for extensionless paths without attempting to add extensions, even in bundler mode where extensionless imports are supposed to work. This caused imports like:

import { greet } from "@repo/library/utils";

to fail with TS2307: Cannot find module '@repo/library/utils' when the package.json had:

{
  "exports": {
    "./*": "./src/*"
  }
}

Solution

Modified loadFileNameFromPackageJsonField() in src/compiler/moduleNameResolver.ts to add extension probing (.ts, .tsx, .d.ts, .js, .jsx) for extensionless paths when not in ESM mode. This mirrors the existing behavior of loadModuleFromFile() for regular imports.

The fix only affects bundler mode - node16 and nodenext modes continue to require explicit extensions as expected.

Changes

Code Change

• src/compiler/moduleNameResolver.ts: Added fallback to tryAddingExtensions() for extensionless paths in non-ESM mode

New Tests

• bundlerWildcardExportsExtensionResolution.ts: Tests that wildcard exports resolve extensionless imports in bundler mode
• node16WildcardExportsRequiresExtension.ts: Verifies node16 mode still requires extensions (negative test)
• wildcardExportsBundlerExtensionlessResolution.ts: Fourslash test for quickInfo on resolved imports

Updated Baselines

Several trace baselines updated to reflect the additional extension probing that now occurs for extensionless paths in package.json fields.