[rush] Build cache does not support symbolic links with relative paths

[chengbapi]

Summary

When the output folder contains a symbolic link, Rush throws an error.

Details

I think this is a good default behavior in most cases, since it helps prevent people from making mistakes.

However, in some cases the symbolic link is a relative path that points to another file within the same repo. Would it make sense to make the symbolic-link check (code linked below) more precise, so that it ignores cases where the relative target resolves to a path inside the repo?

rushstack/libraries/rush-lib/src/logic/buildCache/OperationBuildCache.ts

Line 349 in 98d7c1a

if (child.isSymbolicLink()) {

Standard questions

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

Question	Answer
@microsoft/rush globally installed version?	-
rushVersion from rush.json?	-
useWorkspaces from rush.json?	No
Operating system?	All
Would you consider contributing a PR?	Yes
Node.js version (node -v)?	-

[dmichon-msft]

We categorically don't support putting symbolic links in the build cache because the vast majority of security issues related to unpacking of archives are related to symbolic link handling. It's a difficult thing to get right and we'd need an extremely convincing reason to support them.