[rush] Rush treats npm alias as link when subspace is enabled

[fzxen]

Summary

Rush treats npm alias as link when subspace is enabled.

Repro steps

This repository can reproduce this issue：https://github.com/fzxen/rushstack_reproduce

My project has two subspaces, one is default subspace, and the other is named test-library.

There is a package existing under the default space, which uses npm alias to declare its dependencies.

{
  "devDependencies": {
      "@testing-library/dom": "workspace:*",
      "@testing-library/dom-npm": "npm:@testing-library/dom@^10.4.0"
    }
}

@testing-library/dom is a package in test-library subspace. I expect @testing-library/dom-npm can be downloaded from npm instead of directly creating a local symbol link.

Expected result:

pnpm will download @testing-library/dom from npm.

  ../../../projects/project1:
    devDependencies:
      '@testing-library/dom':
        specifier: link:../test-library-dom
        version: link:../test-library-dom
      '@testing-library/dom-npm':
        specifier: npm:@testing-library/dom@^10.4.0
        version: 10.4.0

Actual result:

pnpm directly links to a package named @testing-library/dom in another sub-space.
I also tried adding @testing-library/dom-npm to decoupledLocalDependencies, but got the same result.

  ../../../projects/project1:
    devDependencies:
      '@testing-library/dom':
        specifier: link:../test-library-dom
        version: link:../test-library-dom
      '@testing-library/dom-npm':
        specifier: link:../test-library-dom
        version: link:../test-library-dom

Details

I located the code causing this problem.

rushstack/libraries/rush-lib/src/logic/pnpm/SubspaceGlobalPnpmfileShim.ts

Lines 127 to 148 in 66196ff

	} else if (currentVersion.startsWith('npm:')) {
	// Case 3. "<alias>": "npm:<package_name>@<dep_version>"
	const packageSpec: string = currentVersion.slice('npm:'.length);
	const nameEndsAt: number =
	packageSpec[0] === '@' ? packageSpec.slice(1).indexOf('@') + 1 : packageSpec.indexOf('@');
	const aliasedPackageName: string = nameEndsAt > 0 ? packageSpec.slice(0, nameEndsAt) : packageSpec;
	// const depVersion: string = nameEndsAt > 0 ? packageSpec.slice(nameEndsAt + 1) : '';
	const aliasedWorkspaceProjectInfo: IWorkspaceProjectInfo | undefined =
	settings.workspaceProjects[aliasedPackageName];
	if (aliasedWorkspaceProjectInfo) {
	const relativePath: string = path.normalize(
	path.relative(
	workspaceProject.projectRelativeFolder,
	aliasedWorkspaceProjectInfo.projectRelativeFolder
	)
	);
	const newVersion: string = 'link:' + relativePath;
	dependencies[dependencyName] = newVersion;
	}
	}
	}
	}

The rush pnpmfile script will resolve npm aliases. As long as there is a dependency with the same name in the workspace, it will directly change to link:.

I think that the original specifier should be maintained and should not be changed to link: When this dependency is added to decoupledLocalDependencies.

Standard questions

Please answer these questions to help us investigate your issue more quickly:

Question	Answer
@microsoft/rush globally installed version?	5.153.1
rushVersion from rush.json?	5.153.1
useWorkspaces from rush.json?	Yes
Operating system?	Mac
Would you consider contributing a PR?	Yes
Node.js version (node -v)?	20.16.0

[iclanton]

Does this repro when subspaces aren't enabled?

Would you be willing to put together a fix?