nixd/Controller: report error on textDocument/definition on builtins

nixd/lib/Controller/AST.h

@@ -39,6 +39,12 @@ struct NotAnIdiomException : IdiomSelectorException {
 
 struct VLAException : std::exception {};
 
+struct NoLocationForBuiltinVariable : std::exception {
+ [[nodiscard]] const char *what() const noexcept override {
+ return "builtins are defined in the interpreter, not in the Nix files";
+ }
+};
+
 /// \brief No such variable.
 struct NoSuchVarException : VLAException {
  [[nodiscard]] const char *what() const noexcept override {

nixd/lib/Controller/Definition.cpp

@@ -115,6 +115,9 @@ const Definition &findVarDefinition(const ExprVar &Var,
 /// \brief Convert nixf::Definition to lspserver::Location
 Location convertToLocation(llvm::StringRef Src, const Definition &Def,
  URIForFile URI) {
+ if (!Def.syntax())
+ throw NoLocationForBuiltinVariable();
+ assert(Def.syntax());
  return Location{
  .uri = std::move(URI),
  .range = toLSPRange(Src, Def.syntax()->range()),
@@ -292,9 +295,10 @@ std::vector<T> mergeVec(std::vector<T> A, const std::vector<T> &B) {
  return A;
 }
 
-Locations defineVar(const ExprVar &Var, const VariableLookupAnalysis &VLA,
- const ParentMapAnalysis &PM, AttrSetClient &NixpkgsClient,
- const URIForFile &URI, llvm::StringRef Src) {
+llvm::Expected<Locations>
+defineVar(const ExprVar &Var, const VariableLookupAnalysis &VLA,
+ const ParentMapAnalysis &PM, AttrSetClient &NixpkgsClient,
+ const URIForFile &URI, llvm::StringRef Src) {
  try {
  Locations StaticLocs = defineVarStatic(Var, VLA, URI, Src);
 
@@ -309,8 +313,9 @@ Locations defineVar(const ExprVar &Var, const VariableLookupAnalysis &VLA,
  }
  } catch (std::exception &E) {
  elog("definition/static: {0}", E.what());
+ return Locations{};
  }
- return {};
+ return error("unreachable code! Please submit an issue");
 }
 
 /// \brief Squash a vector into smaller json variant.

nixd/tools/nixd/test/definition/builtin.md

@@ -0,0 +1,67 @@
+# RUN: nixd --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":"builtins"
+ }
+ }
+}
+```
+
+<-- 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": null
+```
+
+
+```json
+{"jsonrpc":"2.0","method":"exit"}
+```