Fix empty EvalFile option

some GUIs send an empty string for EvalFile, in that case explicitly try the default name

fixes https://github.com/official-stockfish/Stockfish/issues/3675

closes https://github.com/official-stockfish/Stockfish/pull/3678

No functional change.

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 64f9172574a4d7fda710a4ffde587e9ea4fc065d..62d4be847ffd31af8bf032a0d1c248f83cff183a 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -78,6 +78,8 @@ namespace Eval {
         return;
 
     string eval_file = string(Options["EvalFile"]);
+    if (eval_file.empty())
+        eval_file = EvalFileDefaultName;
 
     #if defined(DEFAULT_NNUE_DIRECTORY)
     #define stringify2(x) #x
@@ -118,16 +120,16 @@ namespace Eval {
   void NNUE::verify() {
 
     string eval_file = string(Options["EvalFile"]);
+    if (eval_file.empty())
+        eval_file = EvalFileDefaultName;
 
     if (useNNUE && eval_file_loaded != eval_file)
     {
-        UCI::OptionsMap defaults;
-        UCI::init(defaults);
 
         string msg1 = "If the UCI option \"Use NNUE\" is set to true, network evaluation parameters compatible with the engine must be available.";
         string msg2 = "The option is set to true, but the network file " + eval_file + " was not loaded successfully.";
         string msg3 = "The UCI option EvalFile might need to specify the full path, including the directory name, to the network file.";
-        string msg4 = "The default net can be downloaded from: https://tests.stockfishchess.org/api/nn/" + string(defaults["EvalFile"]);
+        string msg4 = "The default net can be downloaded from: https://tests.stockfishchess.org/api/nn/" + std::string(EvalFileDefaultName);
         string msg5 = "The engine will be terminated now.";
 
         sync_cout << "info string ERROR: " << msg1 << sync_endl;