`builtins.readFileType` regression on symlink handling

[quantenzitrone]

Describe the bug

builtins.readFileType doesn't resolve symlinks

in nix 2.18 and lix it does

Steps To Reproduce

$ mkdir -p test
$ touch test/file
$ ln -s test symlink
$ nix eval --impure --expr 'builtins.readFileType ./symlink/file'
error:
       … while calling the 'readFileType' builtin
         at «string»:1:1:
            1| builtins.readFileType ./symlink/file
             | ^

       error: path '/home/zitrone/symlink' is a symlink

Expected behavior

this is the behavior in nix 2.18 and lix:

$ nix eval --impure --expr 'builtins.readFileType ./symlink/file'
"regular"

Metadata

nix:

nix-env (Nix) 2.31.3`

lix:

nix-env (Lix, like Nix) 2.96.0-dev-pre20260328-dev_d0190cf
System type: x86_64-linux
Additional system types: i686-linux, x86_64-v1-linux, x86_64-v2-linux, x86_64-v3-linux
Features: gc, signed-caches
System configuration file: /etc/nix/nix.conf
User configuration files: /home/zitrone/.config/nix/nix.conf:/etc/xdg/nix/nix.conf:/home/zitrone/.local/share/flatpak/exports/etc/xdg/nix/nix.conf:/var/lib/flatpak/exports/etc/xdg/nix/nix.conf:/home/zitrone/.nix-profile/etc/xdg/nix/nix.conf:/nix/profile/etc/xdg/nix/nix.conf:/home/zitrone/.local/state/nix/profile/etc/xdg/nix/nix.conf:/etc/profiles/per-user/zitrone/etc/xdg/nix/nix.conf:/nix/var/nix/profiles/default/etc/xdg/nix/nix.conf:/run/current-system/sw/etc/xdg/nix/nix.conf
Store directory: /nix/store
State directory: /nix/var/nix
Data directory: /nix/store/ypfrasnv3jwdiw4v2ii5w9dbnc0cih72-lix-2.96.0-dev-pre20260328-dev_d0190cf/share

Additional context

Checklist

• checked latest Nix manual (source)
• checked open bug issues and pull requests for possible duplicates

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[xokdvium]

This should probably be just a matter of doing:

--- a/src/libexpr/primops.cc
+++ b/src/libexpr/primops.cc
@@ -2369,7 +2369,7 @@ static const Value & fileTypeToString(EvalState & state, SourceAccessor::Type ty
 
 static void prim_readFileType(EvalState & state, const PosIdx pos, Value ** args, Value & v)
 {
-    auto path = state.realisePath(pos, *args[0], std::nullopt);
+    auto path = state.realisePath(pos, *args[0], SymlinkResolution::Ancestors);
     /* Retrieve the directory entry type and stringize it. */
     v = fileTypeToString(state, path.lstat().type);
 }