nixd: goto definition(declaration) for nixos options

Fixes: #265

nixd/include/nixd/Controller/Controller.h

@@ -180,7 +180,7 @@ class Controller : public lspserver::LSPServer {
                           lspserver::Callback<lspserver::CompletionItem> Reply);
 
   void onDefinition(const lspserver::TextDocumentPositionParams &Params,
-                    lspserver::Callback<lspserver::Location> Reply);
+                    lspserver::Callback<llvm::json::Value> Reply);
 
   void
   onReferences(const lspserver::TextDocumentPositionParams &Params,

nixd/lib/Controller/AST.cpp

@@ -132,7 +132,9 @@ nixd::findAttrPath(const nixf::Node &N, const nixf::ParentMapAnalysis &PM) {
       AttrPath = getValueAttrPath(*Expr, PM);
     auto Select = getSelectAttrPath(static_cast<const AttrName &>(*Name), PM);
     AttrPath.insert(AttrPath.end(), Select.begin(), Select.end());
-    assert(!AttrPath.empty());
+    // Select "AttrPath" might come from "inherit", thus it can be empty.
+    if (AttrPath.empty())
+      return std::nullopt;
     return AttrPath;
   }
 

nixd/lib/Controller/Definition.cpp

@@ -26,6 +26,7 @@ using namespace llvm;
 
 using LookupResult = VariableLookupAnalysis::LookupResult;
 using ResultKind = VariableLookupAnalysis::LookupResultKind;
+using Locations = std::vector<Location>;
 
 namespace {
 
@@ -165,6 +166,36 @@ class NixpkgsDefinitionProvider {
   }
 };
 
+/// \brief Try to get "location" by invoking options worker
+class OptionsDefinitionProvider {
+  AttrSetClient &Client;
+
+public:
+  OptionsDefinitionProvider(AttrSetClient &Client) : Client(Client) {}
+  void resolveLocations(const std::vector<std::string> &Params,
+                        Locations &Locs) {
+    std::binary_semaphore Ready(0);
+    Expected<OptionInfoResponse> Info = error("not replied");
+    OptionCompleteResponse Names;
+    auto OnReply = [&Ready, &Info](llvm::Expected<OptionInfoResponse> Resp) {
+      Info = std::move(Resp);
+      Ready.release();
+    };
+    // Send request.
+
+    Client.optionInfo(Params, std::move(OnReply));
+    Ready.acquire();
+
+    if (!Info) {
+      elog("getting locations: {0}", Info.takeError());
+      return;
+    }
+
+    for (const auto &Decl : Info->Declarations)
+      Locs.emplace_back(Decl);
+  }
+};
+
 } // namespace
 
 Expected<const Definition &>
@@ -191,7 +222,7 @@ nixd::findDefinition(const Node &N, const ParentMapAnalysis &PMA,
 }
 
 void Controller::onDefinition(const TextDocumentPositionParams &Params,
-                              Callback<Location> Reply) {
+                              Callback<llvm::json::Value> Reply) {
   auto Action = [Reply = std::move(Reply), URI = Params.textDocument.uri,
                  Pos = toNixfPosition(Params.position), this]() mutable {
     std::string File(URI.file());
@@ -200,24 +231,54 @@ void Controller::onDefinition(const TextDocumentPositionParams &Params,
         const VariableLookupAnalysis &VLA = *TU->variableLookup();
         const ParentMapAnalysis &PM = *TU->parentMap();
         const Node *N = AST->descend({Pos, Pos});
+        Locations Locs;
         if (!N) [[unlikely]] {
           Reply(error("cannot find AST node on given position"));
           return;
         }
+        if (std::optional<std::vector<std::string_view>> Path =
+                findAttrPath(*N, PM)) {
+          std::lock_guard _(OptionsLock);
+          // For each option worker, try to get it's decl position.
+          for (const auto &[_, Client] : Options) {
+            if (AttrSetClient *C = Client->client()) {
+              OptionsDefinitionProvider ODP(*C);
+              std::vector<std::string> Params;
+              Params.reserve(Path->size());
+              for (const auto &P : *Path)
+                Params.emplace_back(P);
+              ODP.resolveLocations(Params, Locs);
+            }
+          }
+        }
         if (havePackageScope(*N, VLA, PM) && nixpkgsClient()) {
           // Ask nixpkgs client what's current package documentation.
           NixpkgsDefinitionProvider NDP(*nixpkgsClient());
           auto [Scope, Name] = getScopeAndPrefix(*N, PM);
-          Expected<Location> Loc =
-              NDP.resolvePackage(std::move(Scope), std::move(Name));
-          if (Loc) {
-            Reply(std::move(*Loc));
-            return;
-          }
-          elog("cannot get nixpkgs definition for this package: {0}",
-               Loc.takeError());
+          if (Expected<Location> Loc =
+                  NDP.resolvePackage(std::move(Scope), std::move(Name)))
+            Locs.emplace_back(*Loc);
+          else
+            elog("cannot get nixpkgs definition for package: {0}",
+                 Loc.takeError());
+        }
+
+        if (Expected<Location> StaticLoc = staticDef(URI, *N, PM, VLA))
+          Locs.emplace_back(*StaticLoc);
+        else
+          elog("cannot get static def location: {0}", StaticLoc.takeError());
+
+        if (Locs.empty()) {
+          Reply(nullptr);
+          return;
+        }
+
+        if (Locs.size() == 1) {
+          Reply(Locs.back());
+          return;
         }
-        Reply(staticDef(URI, *N, PM, VLA));
+
+        Reply(std::move(Locs));
         return;
       }
     }

nixd/tools/nixd/test/definition-options.md

@@ -0,0 +1,80 @@
+# RUN: nixd \
+# RUN: --nixos-options-expr="{ foo.declarationPositions = [ { file = \"/foo\"; line = 8; column = 7; } ];  }" \
+# RUN: --lit-test < %s | FileCheck %s
+
+<-- initialize(0)
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":0,
+   "method":"initialize",
+   "params":{
+      "processId":123,
+      "rootPath":"",
+      "capabilities":{
+      },
+      "trace":"off"
+   }
+}
+```
+
+
+<-- textDocument/didOpen
+
+```json
+{
+   "jsonrpc":"2.0",
+   "method":"textDocument/didOpen",
+   "params":{
+      "textDocument":{
+         "uri":"file:///basic.nix",
+         "languageId":"nix",
+         "version":1,
+         "text":"{ foo = 1; }"
+      }
+   }
+}
+```
+
+<-- textDocument/definition(2)
+
+
+```json
+{
+   "jsonrpc":"2.0",
+   "id":2,
+   "method":"textDocument/definition",
+   "params":{
+      "textDocument":{
+         "uri":"file:///basic.nix"
+      },
+      "position":{
+        "line": 0,
+        "character":3
+      }
+   }
+}
+```
+
+```
+     CHECK: "id": 2,
+CHECK-NEXT: "jsonrpc": "2.0",
+CHECK-NEXT: "result": {
+CHECK-NEXT:   "range": {
+CHECK-NEXT:     "end": {
+CHECK-NEXT:       "character": 7,
+CHECK-NEXT:       "line": 8
+CHECK-NEXT:     },
+CHECK-NEXT:     "start": {
+CHECK-NEXT:       "character": 7,
+CHECK-NEXT:       "line": 8
+CHECK-NEXT:     }
+CHECK-NEXT:   },
+CHECK-NEXT:   "uri": "file:///foo"
+```
+
+
+```json
+{"jsonrpc":"2.0","method":"exit"}
+```

nixd/tools/nixd/test/definition-package.md

@@ -58,18 +58,33 @@
 ```
      CHECK: "id": 2,
 CHECK-NEXT: "jsonrpc": "2.0",
-CHECK-NEXT: "result": {
-CHECK-NEXT:   "range": {
-CHECK-NEXT:     "end": {
-CHECK-NEXT:       "character": 33,
-CHECK-NEXT:       "line": 33
+CHECK-NEXT: "result": [
+CHECK-NEXT:   {
+CHECK-NEXT:     "range": {
+CHECK-NEXT:       "end": {
+CHECK-NEXT:         "character": 33,
+CHECK-NEXT:         "line": 33
+CHECK-NEXT:       },
+CHECK-NEXT:       "start": {
+CHECK-NEXT:         "character": 33,
+CHECK-NEXT:         "line": 33
+CHECK-NEXT:       }
 CHECK-NEXT:     },
-CHECK-NEXT:     "start": {
-CHECK-NEXT:       "character": 33,
-CHECK-NEXT:       "line": 33
-CHECK-NEXT:     }
+CHECK-NEXT:     "uri": "file:///foo"
 CHECK-NEXT:   },
-CHECK-NEXT:   "uri": "file:///foo"
+CHECK-NEXT:   {
+CHECK-NEXT:     "range": {
+CHECK-NEXT:       "end": {
+CHECK-NEXT:         "character": 4,
+CHECK-NEXT:         "line": 0
+CHECK-NEXT:       },
+CHECK-NEXT:       "start": {
+CHECK-NEXT:         "character": 0,
+CHECK-NEXT:         "line": 0
+CHECK-NEXT:       }
+CHECK-NEXT:     },
+CHECK-NEXT:     "uri": "file:///basic.nix"
+CHECK-NEXT:   }
 ```