Add inputs.self.submodules flake attribute

src/libcmd/common-eval-args.cc

@@ -34,7 +34,9 @@ EvalSettings evalSettings {
                 // FIXME `parseFlakeRef` should take a `std::string_view`.
                 auto flakeRef = parseFlakeRef(fetchSettings, std::string { rest }, {}, true, false);
                 debug("fetching flake search path element '%s''", rest);
-                auto storePath = flakeRef.resolve(state.store).fetchTree(state.store).first;
+                auto [accessor, lockedRef] = flakeRef.resolve(state.store).lazyFetch(state.store);
+                auto storePath = nix::fetchToStore(*state.store, SourcePath(accessor), FetchMode::Copy, lockedRef.input.getName());
+                state.allowPath(storePath);
                 return state.rootPath(state.store->toRealPath(storePath));
             },
         },
@@ -183,7 +185,9 @@ SourcePath lookupFileArg(EvalState & state, std::string_view s, const Path * bas
     else if (hasPrefix(s, "flake:")) {
         experimentalFeatureSettings.require(Xp::Flakes);
         auto flakeRef = parseFlakeRef(fetchSettings, std::string(s.substr(6)), {}, true, false);
-        auto storePath = flakeRef.resolve(state.store).fetchTree(state.store).first;
+        auto [accessor, lockedRef] = flakeRef.resolve(state.store).lazyFetch(state.store);
+        auto storePath = nix::fetchToStore(*state.store, SourcePath(accessor), FetchMode::Copy, lockedRef.input.getName());
+        state.allowPath(storePath);
         return state.rootPath(CanonPath(state.store->toRealPath(storePath)));
     }
 

src/libexpr/parser.y

@@ -359,11 +359,18 @@ string_parts_interpolated
 
 path_start
   : PATH {
-    Path path(absPath(std::string_view{$1.p, $1.l}, state->basePath.path.abs()));
+    std::string_view literal({$1.p, $1.l});
+    Path path(absPath(literal, state->basePath.path.abs()));
     /* add back in the trailing '/' to the first segment */
-    if ($1.p[$1.l-1] == '/' && $1.l > 1)
-      path += "/";
-    $$ = new ExprPath(ref<SourceAccessor>(state->rootFS), std::move(path));
+    if (literal.size() > 1 && literal.back() == '/')
+      path += '/';
+    $$ =
+        /* Absolute paths are always interpreted relative to the
+           root filesystem accessor, rather than the accessor of the
+           current Nix expression. */
+        literal.front() == '/'
+        ? new ExprPath(state->rootFS, std::move(path))
+        : new ExprPath(state->basePath.accessor, std::move(path));
   }
   | HPATH {
     if (state->settings.pureEval) {

src/libfetchers/fetchers.cc

@@ -186,6 +186,7 @@ bool Input::contains(const Input & other) const
     return false;
 }
 
+// FIXME: remove
 std::pair<StorePath, Input> Input::fetchToStore(ref<Store> store) const
 {
     if (!scheme)
@@ -200,10 +201,6 @@ std::pair<StorePath, Input> Input::fetchToStore(ref<Store> store) const
             auto narHash = store->queryPathInfo(storePath)->narHash;
             result.attrs.insert_or_assign("narHash", narHash.to_string(HashFormat::SRI, true));
 
-            // FIXME: we would like to mark inputs as final in
-            // getAccessorUnchecked(), but then we can't add
-            // narHash. Or maybe narHash should be excluded from the
-            // concept of "final" inputs?
             result.attrs.insert_or_assign("__final", Explicit<bool>(true));
 
             assert(result.isFinal());
@@ -284,6 +281,8 @@ std::pair<ref<SourceAccessor>, Input> Input::getAccessor(ref<Store> store) const
     try {
         auto [accessor, result] = getAccessorUnchecked(store);
 
+        result.attrs.insert_or_assign("__final", Explicit<bool>(true));
+
         checkLocks(*this, result);
 
         return {accessor, std::move(result)};