#include <stdio.h>
int main(int argc, char **argv) { printf("Hello world!n"); return 0; }

$ gcc test.c -o test
 $ ./test
 Hello world!

$ clang test.c -o test -target
 $ ./test
 Hello world!

#include <stdio.h>
#include <float.h>
int main(int argc, char **argv) { printf("Hello world!n"); return 0; }

$ gcc test.c -o test
 $ ./test
 Hello world!

 $ clang test.c -o test -target x86_64-pc-windows-gnu
 In file included from test.c:2:
 In file included from C:llvmbuiltlibclang8.0.0includefloat.h:45:
 C:mingw64-8.1.0x86_64-w64-mingw32includefloat.h:28:15: fatal error: 'float.h' file not found
 #include_next <float.h>
               ^~~~~~~~~
 1 error generated.