foo.cc: In function 'int main()':
foo.cc:6:6: error: redeclaration of 'int x'
  int x=a,y=b
      ^
foo.cc:5:6: note: 'int x' previously declared here
  int x,y;
      ^
foo.cc:6:8: error: 'a' was not declared in this scope
  int x=a,y=b
        ^
foo.cc:5:6: warning: unused variable 'x' [-Wunused-variable]
  int x,y;
      ^
foo.cc:5:8: warning: unused variable 'y' [-Wunused-variable]
  int x,y;
        ^

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