Fixed size comparisons that could lead to infinite loops

src/buffer/out/Row.cpp

@@ -433,7 +433,9 @@ OutputCellIterator ROW::WriteCells(OutputCellIterator it, const til::CoordType c
     auto colorStarts = gsl::narrow_cast<uint16_t>(columnBegin);
     auto currentIndex = colorStarts;
 
-    while (it && currentIndex <= finalColumnInRow)
+    // finalColumnInRow is 32-bit and currentIndex is 16-bit. If finalColumnInRow is higher
+    // than the 16-bit integer limit, we will loop indefinitely.
+    while (it && currentIndex <= saturated_cast<uint16_t>(finalColumnInRow))
     {
         // Fill the color if the behavior isn't set to keeping the current color.
         if (it->TextAttrBehavior() != TextAttributeBehavior::Current)

src/terminal/adapter/SixelParser.cpp

@@ -610,7 +610,9 @@ void SixelParser::_updateTextColors()
     // the text output as well.
     if (_conformanceLevel <= 3 && _maxColors > 2 && _colorTableChanged) [[unlikely]]
     {
-        for (IndexType tableIndex = 0; tableIndex < _maxColors; tableIndex++)
+        // _maxColors is 64-bit and tableIndex is 8-bit. If _maxColors is higher
+        // than the 8-bit integer limit, we will loop indefinitely.
+        for (IndexType tableIndex = 0; tableIndex < (saturated_cast<uint8_t>(_maxColors)); tableIndex++)
         {
             _dispatcher.SetColorTableEntry(tableIndex, _colorFromIndex(tableIndex));
         }

src/terminal/adapter/charsets.hpp

@@ -19,7 +19,7 @@ namespace Microsoft::Console::VirtualTerminal
     public:
         constexpr CharSet(const std::initializer_list<std::pair<wchar_t, wchar_t>> replacements)
         {
-            for (auto i = L'\0'; i < _translationTable.size(); i++)
+            for (size_t i = L'\0'; i < _translationTable.size(); i++)
                 _translationTable.at(i) = BaseChar + i;
             for (auto replacement : replacements)
                 _translationTable.at(replacement.first - BaseChar) = replacement.second;