Remove parent hackery from the path fetcher

Relative paths of subflakes are now handled in lockFlake().

src/libexpr/flake/flakeref.cc

@@ -204,11 +204,8 @@ std::pair<FlakeRef, std::string> parseFlakeRefWithFragment(
         std::string fragment;
         std::swap(fragment, parsedURL.fragment);
 
-        auto input = Input::fromURL(parsedURL);
-        input.parent = baseDir;
-
         return std::make_pair(
-            FlakeRef(std::move(input), getOr(parsedURL.query, "dir", "")),
+            FlakeRef(Input::fromURL(parsedURL), getOr(parsedURL.query, "dir", "")),
             fragment);
     }
 }

src/libfetchers/fetchers.hh

@@ -37,9 +37,6 @@ struct Input
     bool locked = false;
     bool direct = true;
 
-    /* path of the parent of this input, used for relative path resolution */
-    std::optional<Path> parent;
-
 public:
     static Input fromURL(const std::string & url);
 

src/libfetchers/path.cc

@@ -93,23 +93,7 @@ struct PathInputScheme : InputScheme
         if (path[0] == '/')
             return CanonPath(path);
 
-        // FIXME: remove this?
-        if (!input.parent)
         throw Error("cannot fetch input '%s' because it uses a relative path", input.to_string());
-
-        CanonPath parent(*input.parent);
-
-        // the path isn't relative, prefix it
-        auto absPath = CanonPath(path, parent);
-
-        // for security, ensure that if the parent is a store path, it's inside it
-        if (store->isInStore(parent.abs())) {
-            auto storePath = store->printStorePath(store->toStorePath(parent.abs()).first);
-            if (!absPath.isWithin(CanonPath(storePath)))
-                throw BadStorePath("relative path '%s' points outside of its parent's store path '%s'", path, storePath);
-        }
-
-        return absPath;
     }
 
     std::pair<StorePath, Input> fetch(ref<Store> store, const Input & _input) override