cp --no-dereference --preserve=links copies directory symlinks as file symlinks

[basinilya]

cp -a implies --no-dereference --preserve=links

When as an elevated user I archive-copy a directory containing directory symlinks I expect them to be preserved as true directory symlinks but regular file symlinks are created instead in the destination and they're dysfunctional: you cannot list files inside or chdir into them.

>cmd.exe

>"C:\Program Files\coreutils\bin\cp.exe" --version
cp (uutils coreutils) 0.8.0

>mkdir src\aaa1\sub

>mklink /D src\aaa2 aaa1
symbolic link created for src\aaa2 <<===>> aaa1

>dir src
 Directory of L:\BASINPAD\bench\src

09/06/2026  09:32    <DIR>          .
09/06/2026  09:32    <DIR>          ..
09/06/2026  09:32    <DIR>          aaa1
09/06/2026  09:32    <SYMLINKD>     aaa2 [aaa1]
               0 File(s)              0 bytes
               4 Dir(s)  11,395,715,072 bytes free

>"C:\Program Files\coreutils\bin\cp.exe" -av src dst
'src' -> 'dst\'
'src\aaa1' -> 'dst\aaa1'
'src\aaa1\sub' -> 'dst\aaa1\sub'
'src\aaa2' -> 'dst\aaa2'

>dir dst
 Directory of L:\BASINPAD\bench\dst

09/06/2026  09:32    <DIR>          .
09/06/2026  09:32    <DIR>          ..
09/06/2026  09:32    <DIR>          aaa1
09/06/2026  09:32    <SYMLINK>      aaa2 [aaa1]
               1 File(s)              0 bytes
               3 Dir(s)  11,395,715,072 bytes free

>dir src\aaa2\
 Directory of L:\BASINPAD\bench\src\aaa2

09/06/2026  09:32    <DIR>          .
09/06/2026  09:32    <DIR>          ..
09/06/2026  09:32    <DIR>          sub
               0 File(s)              0 bytes
               3 Dir(s)  11,395,715,072 bytes free

>dir dst\aaa2\
 Directory of L:\BASINPAD\bench\dst\aaa2

File Not Found

[caomengxuan666]

I traced this to cp recreating symlinks with std::os::windows::fs::symlink_file unconditionally. On Windows, directory symlinks need to be recreated with symlink_dir; otherwise a copied <SYMLINKD> becomes a regular <SYMLINK> and cannot be used as a directory.

I opened an upstream PR here:
uutils/coreutils#12741

I also pushed a branch against the Microsoft fork's windows/aggregated-fixes branch here:
microsoft/uutils-coreutils@windows/aggregated-fixes...caomengxuan666:uutils-coreutils:fix-windows-cp-directory-symlink

The change uses the source symlink metadata's FILE_ATTRIBUTE_DIRECTORY bit on Windows to decide whether to call symlink_dir or symlink_file, and strengthens the existing directory-symlink copy test.

Verified locally:

• cargo fmt -p uu_cp -- --check
• cargo check -p uu_cp
• manual elevated Windows runtime repro: copied <SYMLINKD> hello_world_symlink [hello_world] with cp.exe -a; the result was <SYMLINKD> test [hello_world], dir test worked, and test\file.txt was readable.