foo.cc:3:7: error: conversion from ‘double’ to ‘long unsigned int’ in a converted constant expression
    3 | int p[1e6];
      |       ^~~
foo.cc:3:7: error: could not convert ‘1.0e+6’ from ‘double’ to ‘long unsigned int’
    3 | int p[1e6];
      |       ^~~
      |       |
      |       double
foo.cc:3:7: error: size of array ‘p’ has non-integral type ‘double’