[hal] Fix USB serial port assignment in SerialHelper

Avoid mutating the sorted hub path list when assigning an unclaimed USB serial port. This keeps the second USB device from reusing the first device's mapping, and resets cached hub/resource state before rescanning.

Author: nobody5050

hal/src/main/native/athena/cpp/SerialHelper.cpp

@@ -138,10 +138,10 @@ void SerialHelper::SortHubPathVector() {
   m_sortedHubPath = m_unsortedHubPath;
   std::sort(m_sortedHubPath.begin(), m_sortedHubPath.end(),
             [](const wpi::SmallVectorImpl<char>& lhs,
-               const wpi::SmallVectorImpl<char>& rhs) -> int {
+               const wpi::SmallVectorImpl<char>& rhs) -> bool {
               std::string_view lhsRef(lhs.begin(), lhs.size());
               std::string_view rhsRef(rhs.begin(), rhs.size());
-              return lhsRef.compare(rhsRef);
+              return lhsRef < rhsRef;
             });
 }
 
@@ -162,6 +162,11 @@ void SerialHelper::CoiteratedSort(
 }
 
 void SerialHelper::QueryHubPaths(int32_t* status) {
+  m_unsortedHubPath.clear();
+  m_visaResource.clear();
+  m_osResource.clear();
+  m_sortedHubPath.clear();
+
   // VISA resource matching string
   const char* str = "?*";
   // Items needed for VISA
@@ -275,12 +280,14 @@ void SerialHelper::QueryHubPaths(int32_t* status) {
         continue;
       }
 
+      std::string_view hubPathComponent = pathSplitVec[hubIndex - 2];
+      std::string_view osPath =
+          wpi::split(wpi::split(osName, "(").second, ")").first;
+
       // Add our devices to our list
-      m_unsortedHubPath.emplace_back(
-          std::string_view{pathSplitVec[hubIndex - 2]});
+      m_unsortedHubPath.emplace_back(hubPathComponent);
       m_visaResource.emplace_back(desc);
-      m_osResource.emplace_back(
-          wpi::split(wpi::split(osName, "(").second, ")").first);
+      m_osResource.emplace_back(osPath);
       break;
     }
   }
@@ -303,14 +310,16 @@ int32_t SerialHelper::GetIndexForPort(HAL_SerialPort port, int32_t* status) {
 
   // If port has not been assigned, find the one to assign
   if (portString.empty()) {
+    // local copy to avoid modifying original
+    auto availableHubPaths = m_sortedHubPath;
+
     for (size_t i = 0; i < 2; i++) {
-      // Remove all used ports
+      // Remove all used ports from the local copy
       auto idx = std::find_if(
-          m_sortedHubPath.begin(), m_sortedHubPath.end(),
+          availableHubPaths.begin(), availableHubPaths.end(),
           [&](const auto& s) { return wpi::equals(s, m_usbNames[i]); });
-      if (idx != m_sortedHubPath.end()) {
-        // found
-        m_sortedHubPath.erase(idx);
+      if (idx != availableHubPaths.end()) {
+        availableHubPaths.erase(idx);
       }
       if (m_usbNames[i] == "") {
         indices.push_back(i);
@@ -330,12 +339,12 @@ int32_t SerialHelper::GetIndexForPort(HAL_SerialPort port, int32_t* status) {
       return -1;
     }
 
-    if (idx >= static_cast<int32_t>(m_sortedHubPath.size())) {
+    if (idx >= static_cast<int32_t>(availableHubPaths.size())) {
       *status = HAL_SERIAL_PORT_NOT_FOUND;
       return -1;
     }
 
-    portString = m_sortedHubPath[idx].str();
+    portString = availableHubPaths[idx].str();
     m_usbNames[port - 2] = portString;
   }