foo.cc: In function 'int main()':
foo.cc:36:3: warning: 'a' may be used uninitialized [-Wmaybe-uninitialized]
   36 | a =a+r;
      | ~~^~~~
foo.cc:8:9: note: 'a' was declared here
    8 |     int a,b;
      |         ^

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