pnpm.fetchDeps produces different hashes depending on whether the build directory and $out are on the same partition. This is a problem for setups where /nix is on its own partition

What we currently put in $out is a pnpm content-addressable store which is hardlinked with files with identical content in node_modules. During the install process for each package in node_modules pnpm will flip the permission executable bit of files that are declared in the bin field in package.json

When the workdir and $out are on the same partition files are properly hardlinked so the bit is flipped in node_modules and in the content-addressable store. When they are in different partitions there is no hardlink so original permissions are preserved in the content-addressable store.

This results in different hashes depending on the situation since permissions are taken into account when calculating the hash.

Here are the solutions that I could imagine:

• Normalize permissions in fixupPhase -> No way to easily know what the permissions should be, may break other things
• Put the store inside the workdir so we know it is on the same partition then copy it to $out

Any idea @Scrumplex @gepbird