foo.cc: In function 'int main(int, char**)':
foo.cc:28:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   28 |         while (nIndex < strExpression.size())
      |                ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
foo.cc:46:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   46 |         while (nIndex < strExpression.size())
      |                ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~
foo.cc:91:35: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<CharUnit>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   91 |                 for (int i = 0; i < vtCharStack.size(); i++)
      |                                 ~~^~~~~~~~~~~~~~~~~~~~
foo.cc:98:43: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<CharUnit>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   98 |                         for (int i = 0; i < vtLeftSet.size(); i++)
      |                                         ~~^~~~~~~~~~~~~~~~~~
foo.cc:27:25: warning: unused variable 'nDepth' [-Wunused-variable]
   27 |         int nIndex = 0, nDepth = 0;
      |                         ^~~~~~
foo.cc:81:27: warning: unused variable 'nRightTag' [-Wunused-variable]
   81 |         int nLeftTag = 0, nRightTag = 0;
      |                           ^~~~~~~~~

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