Hopefully Pizlo will correct me if I get this wrong, but I don't think Fil-C's pointer tagging enforces constness, which isn't needed for C in any case. This C code compiles with no warnings and outputs "Howlong\n" with GCC 12.2.0-14 -ansi -pedantic -Wall -Wextra:

    #include <stdio.h>

    int main()
    {
      const char c[] = "Howling\n";
      char *p = (char*)c;
      p[4] = 'o';
      printf("%s", c);
      return 0;
    }

Somewhat to my surprise, it still compiles successfully with no warnings as C++ (renaming to deconst.cc and compiling with g++). I don't know C++ that well, since I've only been using it for 35 years, which isn't nearly long enough to learn the whole language unless you write a compiler for it.

Same results with Debian clang (and clang++) version 14.0.6 with the same options.

Of course, if you change c[] to *c, it will segfault. But it still compiles successfully without warnings.

Laundering your pointer through an integer is evidently not necessary.