Fix build-tree DLL search: add conda Library/bin for pyexpat and other extensions

Author: akenmorris

Libs/Application/Job/PythonWorker.cpp

@@ -246,15 +246,26 @@ bool PythonWorker::init() {
     AddDllDirectory(dlls_dir.toStdWString().c_str());
     AddDllDirectory(python_home.toStdWString().c_str());
 
-    // Also add the directory containing ShapeWorksStudio.exe (for dependency DLLs)
+    // Also add the directory containing the executable (for dependency DLLs)
     QString app_dir = QCoreApplication::applicationDirPath();
     AddDllDirectory(app_dir.toStdWString().c_str());
 
-    // Also prepend DLLs/ and python home to PATH. In the embedded interpreter,
+    // In the build tree, PYTHONHOME points to conda's prefix. Conda's .pyd
+    // files need DLLs from conda's Library/bin/ (e.g. libexpat.dll for pyexpat).
+    QString conda_library_bin = python_home + "/Library/bin";
+    if (QDir(conda_library_bin).exists()) {
+      AddDllDirectory(conda_library_bin.toStdWString().c_str());
+    }
+
+    // Prepend DLL directories to PATH as well. In the embedded interpreter,
     // implicit DLL dependencies of .pyd files (e.g. _ctypes.pyd -> libffi-8.dll)
-    // are not found via AddDllDirectory alone — PATH is still needed.
+    // are not always found via AddDllDirectory alone — PATH is still needed.
     QString current_path = qgetenv("PATH");
-    QString new_path = dlls_dir + ";" + python_home + ";" + app_dir + ";" + current_path;
+    QString new_path = dlls_dir + ";" + python_home + ";" + app_dir;
+    if (QDir(conda_library_bin).exists()) {
+      new_path += ";" + conda_library_bin;
+    }
+    new_path += ";" + current_path;
     qputenv("PATH", new_path.toUtf8());
 
     SW_LOG("Registered bundled Python DLL directories");