Don't change nix::fs for now

src/libutil/file-system.cc

@@ -29,7 +29,7 @@
 
 namespace nix {
 
-namespace fs = std::filesystem;
+namespace fs { using namespace std::filesystem; }
 
 /**
  * Treat the string as possibly an absolute path, by inspecting the

src/libutil/file-system.hh

@@ -126,6 +126,8 @@ std::optional<struct stat> maybeLstat(const Path & path);
  */
 bool pathExists(const Path & path);
 
+namespace fs {
+
 /**
  *  ```
  *  symlink_exists(p) = std::filesystem::exists(std::filesystem::symlink_status(p))
@@ -139,6 +141,8 @@ inline bool symlink_exists(const std::filesystem::path & path) {
     return std::filesystem::exists(std::filesystem::symlink_status(path));
 }
 
+} // namespace fs
+
 /**
  * A version of pathExists that returns false on a permission error.
  * Useful for inferring default paths across directories that might not

src/libutil/tarfile.cc

@@ -8,7 +8,9 @@
 
 namespace nix {
 
-namespace fs = std::filesystem;
+namespace fs {
+using namespace std::filesystem;
+}
 
 namespace {