foo.cc: In function 'int main()':
foo.cc:15:5: warning: 'sum' is used uninitialized in this function [-Wuninitialized]
  sum+=g+s+t;
  ~~~^~~~~~~
foo.cc:15:10: warning: 't' may be used uninitialized in this function [-Wmaybe-uninitialized]
  sum+=g+s+t;
       ~~~^~
foo.cc:12:4: warning: 's' may be used uninitialized in this function [-Wmaybe-uninitialized]
   s+=x2;
   ~^~~~
foo.cc:11:4: warning: 'g' may be used uninitialized in this function [-Wmaybe-uninitialized]
   g+=x1;
   ~^~~~

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