nixd/AST: drop lib.attrValues attribute keys from option paths

nixd/lib/Controller/AST.cpp

@@ -15,6 +15,29 @@ struct AttrPathHasDynamicError : std::exception {
   }
 };
 
+/// \brief Is \p Call a call to `<x>.attrValues <arg>` (e.g. `lib.attrValues`,
+/// `builtins.attrValues`) with a single argument?
+///
+/// Purely syntactic: matches an ExprSelect callee whose last AttrPath name
+/// is `attrValues`. Doesn't resolve through identifier rebinding. False
+/// positives are bounded by the options-tree lookup downstream — a
+/// misrecognized call only causes the analyzer to construct a path that
+/// won't match any real option, producing no hover (same as today).
+bool isAttrValuesCall(const nixf::ExprCall &Call) {
+  if (Call.args().size() != 1)
+    return false;
+  const nixf::Expr &Fn = Call.fn();
+  if (Fn.kind() != Node::NK_ExprSelect)
+    return false;
+  const auto &Sel = static_cast<const nixf::ExprSelect &>(Fn);
+  const nixf::AttrPath *SelPath = Sel.path();
+  if (!SelPath || SelPath->names().empty())
+    return false;
+  const auto &LastName = SelPath->names().back();
+  return LastName && LastName->isStatic() &&
+         LastName->staticName() == "attrValues";
+}
+
 /// \brief Find nested attrpath.
 /// e.g.   a.b.c.d
 ///               ^<-  a.b.c.d
@@ -62,6 +85,22 @@ void getValueAttrPath(const nixf::Node &N, const nixf::ParentMapAnalysis &PM,
   if (Up->kind() != Node::NK_ExprAttrs)
     return;
 
+  // Transparency for `lib.attrValues <attrset>` / `builtins.attrValues
+  // <attrset>`. When the enclosing attrset is itself the sole argument of an
+  // attrValues call, the call discards the attribute names — the keys of
+  // `Up` are not option-path components. Recurse past the call as if
+  // `N` were a list-literal element of the surrounding context, without
+  // appending `N`'s key in `Up`.
+  if (const nixf::Node *UpUp = PM.query(*Up)) {
+    if (UpUp->kind() == Node::NK_ExprCall) {
+      const auto &Call = static_cast<const nixf::ExprCall &>(*UpUp);
+      if (isAttrValuesCall(Call) && Call.args()[0].get() == Up) {
+        getValueAttrPath(Call, PM, Path);
+        return;
+      }
+    }
+  }
+
   std::vector<std::string_view> Basic;
   // Recursively search up all nested entries
   if (!PM.isRoot(*Up))

nixd/tools/nixd/test/hover/attrvalues-transparency.md

@@ -0,0 +1,60 @@
+# RUN: nixd --lit-test \
+# RUN: --nixos-options-expr="{ services.openssh.enable = { _type = \"option\"; description = \"openssh option\"; type.description = \"bool\"; }; }" \
+# RUN: < %s | FileCheck %s
+
+# Cursor on `enable` inside `lib.mkMerge (lib.attrValues { ssh = MODULE; })`.
+# Without the attrValues transparency in AST.cpp::getValueAttrPath, the
+# attribute key `ssh` would be incorrectly prepended to the option path,
+# producing the unresolvable `ssh.services.openssh.enable` and no hover.
+# With it, the key is treated as transparent (since attrValues discards
+# names) and the option resolves normally.
+
+<-- initialize(0)
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":0,
+   "method":"initialize",
+   "params":{"processId":123,"rootPath":"","capabilities":{},"trace":"off"}
+}
+```
+
+
+<-- textDocument/didOpen
+
+```nix file:///test.nix
+{ lib, ... }: lib.mkMerge (lib.attrValues {
+  ssh = {
+    services.openssh.enable = true;
+  };
+})
+```
+
+
+<-- textDocument/hover(2)
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":2,
+   "method":"textDocument/hover",
+   "params":{
+      "textDocument":{"uri":"file:///test.nix"},
+      "position":{"line":2,"character":23}
+   }
+}
+```
+
+```
+     CHECK: "id": 2,
+CHECK-NEXT: "jsonrpc": "2.0",
+CHECK-NEXT: "result": {
+CHECK-NEXT:   "contents": {
+CHECK-NEXT:     "kind": "markdown",
+CHECK-NEXT:     "value": " (bool)\n\nopenssh option"
+```
+
+```json
+{"jsonrpc":"2.0","method":"exit"}
+```