Function findLatestQGISInstallationPath

src/proj_loader.cpp:347–471

Finds the latest QGIS installation path by first checking the `QGIS_PREFIX_PATH` environment variable. If the environment variable is not set, it searches through default installation directories and selects the latest version based on directory names. appends "bin" to the path, where the proj lib is located

/// If the environment variable is not set, it searches through default installation directories and selects the latest version based on directory names.
/// appends "bin" to the path, where the proj lib is located
static std::string findLatestQGISInstallationPath(std::set<std::filesystem::path>& searchedPaths) {
  // 1. Check the environment variable QGIS_PREFIX_PATH
  const char* qgisPathEnv = getenv("QGIS_PREFIX_PATH");
  std::string latestVersionPath;
  std::string latestVersionName;

#ifdef _WIN32
  if (qgisPathEnv) {
    try {
      if (std::filesystem::exists(qgisPathEnv)) {
        std::filesystem::path path(qgisPathEnv);
        path /= "bin";  // Append "bin" to the path
        if (std::filesystem::exists(path))  {
          searchedPaths.insert(path);
          LASMessage(LAS_VERY_VERBOSE, "PROJ library used via QGIS installation path: %s", path.string().c_str());
          return path.string();
        } else {
          LASMessage(LAS_WARNING, "QGIS_PREFIX_PATH set but bin folder [%s] not found", path.string().c_str());
        }
      } else {
        LASMessage(LAS_WARNING, "QGIS_PREFIX_PATH set [%s] but not found", qgisPathEnv);
      }
    } catch (const std::filesystem::filesystem_error&) {
    }
  }

// 2. If the environment variable is not set, check default paths
  size_t numPaths = 0;
  const char** defaultPaths = getDefaultProgramPaths(numPaths);

  // Checking the standard paths (e.g. "C:\Program Files\QGIS 3.36.3\bin\qgis-bin.exe")
  for (size_t i = 0; i < numPaths; ++i) {
    const char* pathCStr = defaultPaths[i];
    if (!pathCStr) continue;

    searchedPaths.insert(std::filesystem::path(pathCStr));
    for (const auto& programEntry : std::filesystem::directory_iterator(pathCStr)) {
      try {
        if (std::filesystem::is_directory(programEntry.path())) {
          std::string folderName = programEntry.path().filename().string();
          // Check whether the name begins with QGIS 
          if (folderName.rfind("QGIS ") == 0) {
            searchedPaths.insert(std::filesystem::path(programEntry.path()));

            if (latestVersionName.empty() || compareVersions(folderName, latestVersionName)) {
              latestVersionName = folderName;
              std::filesystem::path path(programEntry.path());
              path /= "bin";  // Append "bin" to the path
              if (std::filesystem::exists(path)) {
                searchedPaths.insert(path);
                latestVersionPath = path.string();
              }
            }
          }
        }
      }
      catch (const std::filesystem::filesystem_error&) {
        continue;