foo.cc: In function 'int main()':
foo.cc:15:5: error: unable to find numeric literal operator 'operator""x'
   15 |   y=2x-1;
      |     ^~
foo.cc:15:5: note: use '-fext-numeric-literals' to enable more built-in suffixes
foo.cc:19:5: error: unable to find numeric literal operator 'operator""x'
   19 |   y=3x+4;
      |     ^~
foo.cc:19:5: note: use '-fext-numeric-literals' to enable more built-in suffixes
foo.cc:23:8: error: unable to find numeric literal operator 'operator""x'
   23 |   y=90-5x;
      |        ^~
foo.cc:23:8: note: use '-fext-numeric-literals' to enable more built-in suffixes
foo.cc:27:8: error: unable to find numeric literal operator 'operator""x'
   27 |   y=80+3x;
      |        ^~
foo.cc:27:8: note: use '-fext-numeric-literals' to enable more built-in suffixes

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