buildLibsFromSource: false doesn't work with Vite executors when package.json has no exports field

[ms-tng]

Current Behavior

Suppose an app my-app uses the @nx/vite:dev-server executor and depends on a lib my-lib. Then when the buildLibsFromSource option of the executor is set to false, my-lib is still built from source within my-app.

First of all, this fails because of #18458, but even after patching that, it still doesn't work.

The reason is that when the new vite-tsconfig-paths plugin tries to find the bundled module in the build artifacts of the lib, it first checks for an exports field in package.json, then for module and main, see here:

nx/packages/vite/plugins/nx-tsconfig-paths.plugin.ts

Line 36 in 50a145b

['exports', '.', 'import'],

When there is no exports field (which is currently the default for a Rollup build, for example), the check for exports throws and the plugin falls back to using the default tsconfig, not the tsconfig.generated.json pointing at the build artifacts.

Expected Behavior

my-lib is not built from source, but its build artifact is used instead.

GitHub Repo

No response

Steps to Reproduce

1. Patch @nx/vite to fix buildLibsFromSource: false doesn't work with Vite dev-server executor #18458 by replacing context.targetName with 'build' in executor-utils
2. Create a Vite app and a lib, where the app depends on the lib
3. Set "buildLibsFromSource": false for the serve target of the app
4. Build the lib and serve the app
5. Open the app in a browser and observe that the lib is built from its sources

Nx Report

Node   : 20.2.0
OS     : win32-x64

@nx/express        : 16.6.0
@nx/node           : 16.6.0
@nx/plugin         : 16.6.0
@nx/react          : 16.6.0
@nx/rollup         : 16.6.0
@nx/storybook      : 16.6.0
@nrwl/tao          : 16.6.0
@nx/vite           : 16.6.0
@nx/web            : 16.6.0
typescript         : 5.1.6

Failure Logs

No response

Operating System

• macOS
• Linux
• Windows
• Other (Please specify)

Additional Information

No response

[barbados-clemens]

this should be resolved with #18477
i still need to do more testing, but basically will allow projects without package.json or export fields to work.

[ms-tng]

@barbados-clemens Thanks for the fix!

Unfortunately, the issue persists in Nx 16.8.0. I created another reproducing example at https://github.com/ms-tng/nx-buildlibsfromsource-repro2.

When the lib has an exports field, everything works as expected: Setting "buildLibsFromSource": false in the app causes the app to use the build artifact of the lib. When there is no exports field, however, the lib is built/served from source.

Could you take another look?

[ms-tng]

Ok, I figured it out: You can set the mainFields option of the nxViteTsPaths Vite plugin to something not containing exports, e.g.:

nxViteTsPaths({
  mainFields: ['module', 'main'],
}),

The default setting is [['exports', '.', 'import'], 'module', 'main'], which causes the issue when there is no exports field.

[github-actions]

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