Merge pull request #263478 from tweag/fileset/unknown-type-error

      # Filter suited when there's some files

      # This can't be used for when there's no files, because the base directory is always included

      nonEmpty =

        path: _:

        path: type:

        let

          # Add a slash to the path string, turning "/foo" to "/foo/",

          # making sure to not have any false prefix matches below.

          # meaning this function can never receive "/" as an argument

          pathSlash = path + "/";

        in

        (

          # Same as `hasPrefix pathSlash baseString`, but more efficient.

          # With base /foo/bar we need to include /foo:

          # hasPrefix "/foo/" "/foo/bar/"

            # inTree (split "/" (removePrefix "/foo/" "/foo/bar/baz"))

            # == inTree (split "/" "bar/baz")

            # == inTree [ "bar" "baz" ]

          inTree (split "/" (substring baseLength (-1) path));

            inTree (split "/" (substring baseLength (-1) path))

        )

        # This is a way have an additional check in case the above is true without any significant performance cost

        && (

          # This relies on the fact that Nix only distinguishes path types "directory", "regular", "symlink" and "unknown",

          # so everything except "unknown" is allowed, seems reasonable to rely on that

          type != "unknown"

          || throw ''

            lib.fileset.toSource: `fileset` contains a file that cannot be added to the store: ${path}

                This file is neither a regular file nor a symlink, the only file types supported by the Nix store.

                Therefore the file set cannot be added to the Nix store as is. Make sure to not include that file to avoid this error.''

        );

    in

    # Special case because the code below assumes that the _internalBase is always included in the result

    # which shouldn't be done when we have no files at all in the base

\s*`root`: root "'"$work"'/foo/mock-root"

\s*`fileset`: root "'"$work"'/bar/mock-root"

\s*Different roots are not supported.'

rm -rf *

rm -rf -- *

# `root` needs to exist

expectFailure 'toSource { root = ./a; fileset = ./.; }' 'lib.fileset.toSource: `root` \('"$work"'/a\) does not exist.'

expectFailure 'toSource { root = ./a; fileset = ./a; }' 'lib.fileset.toSource: `root` \('"$work"'/a\) is a file, but it should be a directory instead. Potential solutions:

\s*- If you want to import the file into the store _without_ a containing directory, use string interpolation or `builtins.path` instead of this function.

\s*- If you want to import the file into the store _with_ a containing directory, set `root` to the containing directory, such as '"$work"', and set `fileset` to the file path.'

rm -rf *

rm -rf -- *

# The fileset argument should be evaluated, even if the directory is empty

expectFailure 'toSource { root = ./.; fileset = abort "This should be evaluated"; }' 'evaluation aborted with the following error message: '\''This should be evaluated'\'

expectFailure 'toSource { root = ./a; fileset = ./.; }' 'lib.fileset.toSource: `fileset` could contain files in '"$work"', which is not under the `root` \('"$work"'/a\). Potential solutions:

\s*- Set `root` to '"$work"' or any directory higher up. This changes the layout of the resulting store path.

\s*- Set `fileset` to a file set that cannot contain files outside the `root` \('"$work"'/a\). This could change the files included in the result.'

rm -rf *

rm -rf -- *

# non-regular and non-symlink files cannot be added to the Nix store

mkfifo a

expectFailure 'toSource { root = ./.; fileset = ./a; }' 'lib.fileset.toSource: `fileset` contains a file that cannot be added to the store: '"$work"'/a

\s*This file is neither a regular file nor a symlink, the only file types supported by the Nix store.

\s*Therefore the file set cannot be added to the Nix store as is. Make sure to not include that file to avoid this error.'

rm -rf -- *

# Path coercion only works for paths

expectFailure 'toSource { root = ./.; fileset = 10; }' 'lib.fileset.toSource: `fileset` is of type int, but it should be a file set or a path instead.'

\s*element 0: root "'"$work"'/foo/mock-root"

\s*element 1: root "'"$work"'/bar/mock-root"

\s*Different roots are not supported.'

rm -rf *

rm -rf -- *

# Coercion errors show the correct context

expectFailure 'toSource { root = ./.; fileset = union ./a ./.; }' 'lib.fileset.union: first argument \('"$work"'/a\) does not exist.'