foo.cc: In function 'int main()':
foo.cc:11:8: warning: unused variable 'a' [-Wunused-variable]
   11 |  float a=1,sum;
      |        ^
foo.cc:17:6: warning: 'sum' may be used uninitialized in this function [-Wmaybe-uninitialized]
   17 |   sum+=z;
      |   ~~~^~~

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