fixes SetColumnName/SetRowName not removing old name from label map

SetColumnName and SetRowName add the new name to the internal label
map but do not remove the old name. After renaming, the old name
still resolves via GetColumnIdx/GetRowIdx, which can cause silent
data misdirection when the old name is used after a rename.

Remove the old name from the map before inserting the new one.
Add test104 to verify old names are properly cleaned up.

Author: MarkLee131

CMakeLists.txt

@@ -193,6 +193,7 @@ if(RAPIDCSV_BUILD_TESTS)
   endif()
   add_unit_test(test102)
   add_unit_test(test103)
+  add_unit_test(test104)
 
   # perf tests
   add_perf_test(ptest001)

src/rapidcsv.h

@@ -1448,6 +1448,14 @@ namespace rapidcsv
       }
 
       const size_t dataColumnIdx = GetDataColumnIndex(pColumnIdx);
+
+      // remove old name from map before adding new one
+      const size_t nameRowIdx = static_cast<size_t>(mLabelParams.mColumnNameIdx);
+      if ((nameRowIdx < mData.size()) && (dataColumnIdx < mData.at(nameRowIdx).size()))
+      {
+        const std::string oldName = mData.at(nameRowIdx).at(dataColumnIdx);
+        mColumnNames.erase(oldName);
+      }
       mColumnNames[pColumnName] = dataColumnIdx;
 
       // increase table size if necessary:
@@ -1505,6 +1513,14 @@ namespace rapidcsv
     void SetRowName(size_t pRowIdx, const std::string& pRowName)
     {
       const size_t dataRowIdx = GetDataRowIndex(pRowIdx);
+
+      // remove old name from map before adding new one
+      if ((mLabelParams.mRowNameIdx >= 0) && (dataRowIdx < mData.size()) &&
+          (static_cast<size_t>(mLabelParams.mRowNameIdx) < mData.at(dataRowIdx).size()))
+      {
+        const std::string oldName = mData.at(dataRowIdx).at(static_cast<size_t>(mLabelParams.mRowNameIdx));
+        mRowNames.erase(oldName);
+      }
       mRowNames[pRowName] = dataRowIdx;
       if (mLabelParams.mRowNameIdx < 0)
       {

tests/test104.cpp

@@ -0,0 +1,61 @@
+// test104.cpp - SetColumnName / SetRowName stale label cleanup
+
+#include <rapidcsv.h>
+#include "unittest.h"
+
+int main()
+{
+  int rv = 0;
+
+  std::string csv =
+    "name,value\n"
+    "row1,100\n"
+    "row2,200\n"
+  ;
+
+  std::string path = unittest::TempPath();
+  unittest::WriteFile(path, csv);
+
+  try
+  {
+    // Test 1: SetColumnName removes old name from map
+    {
+      rapidcsv::Document doc(path, rapidcsv::LabelParams(0, 0));
+
+      unittest::ExpectEqual(int, doc.GetColumnIdx("value"), 0);
+      doc.SetColumnName(0, "price");
+      unittest::ExpectEqual(int, doc.GetColumnIdx("price"), 0);
+      unittest::ExpectEqual(int, doc.GetColumnIdx("value"), -1);
+    }
+
+    // Test 2: SetRowName removes old name from map
+    {
+      rapidcsv::Document doc(path, rapidcsv::LabelParams(0, 0));
+
+      unittest::ExpectEqual(int, doc.GetRowIdx("row1"), 0);
+      doc.SetRowName(0, "item1");
+      unittest::ExpectEqual(int, doc.GetRowIdx("item1"), 0);
+      unittest::ExpectEqual(int, doc.GetRowIdx("row1"), -1);
+    }
+
+    // Test 3: Data access by new name works correctly
+    {
+      rapidcsv::Document doc(path, rapidcsv::LabelParams(0, 0));
+
+      doc.SetColumnName(0, "price");
+      unittest::ExpectEqual(std::string, doc.GetCell<std::string>("price", "row1"), "100");
+
+      doc.SetRowName(0, "item1");
+      unittest::ExpectEqual(std::string, doc.GetCell<std::string>("price", "item1"), "100");
+    }
+  }
+  catch (const std::exception& ex)
+  {
+    std::cout << ex.what() << std::endl;
+    rv = 1;
+  }
+
+  unittest::DeleteFile(path);
+
+  return rv;
+}