preprocess with `gcc -E -std=c99 quine.c -o quine.i` and compile with `gcc -std=gnu99 quine.i -o quine`

quine.c

#include <stdio.h>
#ifdef A
R"("
#else
#define A
const char *s =
#include __FILE__
;
#undef A
#endif
int main() {
 char* pre = "#include <stdio.h>\n#ifdef A\nR\"(\"\n#else\n#define A\nconst char *s =\n#include __FILE__\n;\n#undef A\n#endif\n";
 char* post = "#ifdef A\n\")\"\n#endif\n";
 printf("%s%.235s%s",pre,s+9,post);
 return 0;
}
#ifdef A
")"
#endif