Description

When running compilation from a nested directory (e.g., /lib/my-lib) with output set to the root using --output ../../output, the cache-db saves file paths relative to the current working directory.

This causes the cache to be invalidated when compilation is subsequently run from the root directory or from a differently nested directory, resulting in a full rebuild.

To Reproduce

1. Navigate to a subdirectory within your project
2. Compile with the output directory set at a higher level than the current working directory
3. Observe that file paths in cache-db.json are relative to the current working directory (e.g., ../../.spago/some-root-dep)
4. Run compilation from a different directory and observe that the cache is invalidated

Expected behavior

File paths could be stored relative to the location of cache-db.json - the output folder - rather than relative to the working directory from which compilation was run. This would ensure cache consistency regardless of where compilation is invoked.

PureScript version

0.15.15