Add verbose DLL diagnostics to debug GHA segfault during Python init

Author: akenmorris

Libs/Application/Job/PythonWorker.cpp

@@ -246,6 +246,40 @@ bool PythonWorker::init() {
     QString current_path = qgetenv("PATH");
     qputenv("PATH", (dlls_dir + ";" + python_home + ";" + app_dir + ";" + current_path).toUtf8());
 
+    // Verbose diagnostics for debugging GHA failures
+    std::cerr << "=== Bundled Python DLL diagnostics ===\n";
+    std::cerr << "  app_dir: " << app_dir.toStdString() << "\n";
+    std::cerr << "  python_home: " << python_home.toStdString() << "\n";
+    std::cerr << "  DLLs dir: " << dlls_dir.toStdString() << "\n";
+    std::cerr << "  DLLs dir exists: " << QDir(dlls_dir).exists() << "\n";
+    std::cerr << "  python_home/Library/bin exists: " << QDir(python_home + "/Library/bin").exists() << "\n";
+
+    // Check critical files
+    QStringList check_files = {
+        python_home + "/python312.dll",
+        python_home + "/python3.dll",
+        python_home + "/DLLs/pyexpat.pyd",
+        python_home + "/Library/bin/libexpat.dll",
+        python_home + "/Lib/os.py",
+        app_dir + "/python312.dll",
+        app_dir + "/libexpat.dll",
+    };
+    for (const auto& f : check_files) {
+      std::cerr << "  " << f.toStdString() << " : " << (QFile::exists(f) ? "EXISTS" : "MISSING") << "\n";
+    }
+
+    // List DLLs in app_dir matching python* or lib*
+    QDir app_dir_obj(app_dir);
+    QStringList dll_filters = {"python*.dll", "lib*.dll"};
+    auto dlls_in_app = app_dir_obj.entryList(dll_filters, QDir::Files);
+    std::cerr << "  DLLs in app_dir: ";
+    for (const auto& d : dlls_in_app) std::cerr << d.toStdString() << " ";
+    std::cerr << "\n";
+
+    std::cerr << "  PATH (first 500 chars): " << qgetenv("PATH").left(500).toStdString() << "\n";
+    std::cerr << "=== End diagnostics ===\n";
+    std::cerr.flush();
+
     SW_LOG("Registered bundled Python DLL directories");
   } else {
     // Legacy conda-based Python path
@@ -284,7 +318,11 @@ bool PythonWorker::init() {
 #endif  // ifdef _WIN32
 
   try {
+    std::cerr << "=== About to call py::initialize_interpreter() ===\n";
+    std::cerr.flush();
     py::initialize_interpreter();
+    std::cerr << "=== py::initialize_interpreter() succeeded ===\n";
+    std::cerr.flush();
     interpreter_started_ = true;
 
     py::module sys = py::module::import("sys");

cmake/BundledPython.cmake

@@ -107,20 +107,28 @@ if(WIN32)
   set(_conda_prefix "${_conda_prefix}")
   message(STATUS "Windows: skipping conda extension copy (bundled Python has its own DLLs)")
 
-  # Copy conda's Library/bin DLLs to the build output directory so the embedded
-  # interpreter can find them. Conda's .pyd extensions (pyexpat, _ssl, etc.) have
-  # implicit DLL dependencies (libexpat, libssl, etc.) in Library/bin/. In the
-  # build tree, the application directory is always searched for DLLs, so placing
-  # them next to the executables is the most reliable approach.
+  # Copy specific conda DLLs needed by Python's .pyd extensions to the build
+  # output directory. Conda's .pyd extensions (pyexpat, _ssl, etc.) have implicit
+  # DLL dependencies in Library/bin/. We only copy the Python-specific ones to
+  # avoid conflicting with Qt/VTK/Boost DLLs already in the build directory.
   set(_conda_lib_bin "${_conda_prefix}/Library/bin")
-  if(EXISTS "${_conda_lib_bin}")
-    file(GLOB _conda_dlls "${_conda_lib_bin}/*.dll")
-    list(LENGTH _conda_dlls _num_dlls)
-    message(STATUS "Copying ${_num_dlls} DLLs from conda Library/bin to build output")
-    file(COPY ${_conda_dlls} DESTINATION "${CMAKE_BINARY_DIR}/bin/Release")
-    # Also copy to bin/ for NMake builds
-    file(COPY ${_conda_dlls} DESTINATION "${CMAKE_BINARY_DIR}/bin")
-  endif()
+  set(_python_dep_dlls
+    libexpat.dll        # pyexpat.pyd
+    libssl-3-x64.dll    # _ssl.pyd
+    libcrypto-3-x64.dll # _hashlib.pyd
+    libffi-8.dll        # _ctypes.pyd (if present)
+    zlib.dll            # zlib module
+    libbz2.dll          # _bz2.pyd
+    liblzma.dll         # _lzma.pyd
+    sqlite3.dll         # _sqlite3.pyd
+  )
+  foreach(_dll ${_python_dep_dlls})
+    if(EXISTS "${_conda_lib_bin}/${_dll}")
+      message(STATUS "Copying ${_dll} from conda Library/bin to build output")
+      file(COPY "${_conda_lib_bin}/${_dll}" DESTINATION "${CMAKE_BINARY_DIR}/bin/Release")
+      file(COPY "${_conda_lib_bin}/${_dll}" DESTINATION "${CMAKE_BINARY_DIR}/bin")
+    endif()
+  endforeach()
 else()
   get_filename_component(_conda_prefix "${_conda_prefix}" DIRECTORY)       # .../
   set(_conda_lib_dynload "${_conda_prefix}/lib/python3.12/lib-dynload")