foo.cc: In function 'int main(int, const char**)':
foo.cc:11:26: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   11 |     for (size_t i = 0; i < kinds; i++)
      |                        ~~^~~~~~~
foo.cc:15:26: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   15 |     for (size_t i = 0; i < kinds; i++)
      |                        ~~^~~~~~~
foo.cc:25:30: warning: comparison of integer expressions of different signedness: 'size_t' {aka 'long unsigned int'} and 'int' [-Wsign-compare]
   25 |         for (size_t i = 0; i < kinds; i++)
      |                            ~~^~~~~~~

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