foo.cc: In function 'int main()':
foo.cc:16:9: warning: empty parentheses were disambiguated as a function declaration [-Wvexing-parse]
   16 | int main()
      |         ^~
foo.cc:16:9: note: remove parentheses to default-initialize a variable
   16 | int main()
      |         ^~
      |         --
foo.cc:16:9: note: or replace parentheses with braces to value-initialize a variable
foo.cc:17:1: error: a function-definition is not allowed here before '{' token
   17 | {
      | ^

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