Use the real path for resolving dependencies

[zkochan]

Node uses the real path of modules (except when executed with --preserve-symlinks) to resolve dependencies. That is why pnpm's symlinked node_modules work fine with Node applications.

However, resolve is a really popular and widely used package and it does not use the real path of modules to resolve dependencies. As a consequence, a lot of tooling fails with pnpm. See the most recent issue: pnpm/pnpm#857. And also many of these might be related: pnpm/pnpm#801

Would you accept a pull request to change the behavior of resolve to work the way Node does? It won't change anything for projects that use npm/Yarn because they don't leverage symlinks but it would be a huge help for the pnpm community!

[ljharb]

Sure, that sounds good - let's ensure that a) existing tests keep passing (ofc), b) we add a "preserve symlinks" option, so users can control the behavior if they like, and c) let's think carefully about if it's possible to avoid a semver-major.

[malash]

@zkochan Did you forget to change this condition when resolving real path for basedir ?

resolve/lib/sync.js

Line 29 in fed3f0f

var res = path.resolve(y, x);

E.g. this line may fail require('resolve').sync('../../path/to/another/package', { basedir: '/path/to/a/symlink' }).

FYI @ljharb

[ljharb]

@malash could you file a separate issue for that, with a test case?