> That wasn't quite what I was trying to show with the snippet - I was intimating that you can use tcc to run C directly in something like a shell script.

I know, but the first example in the link was:

  $ runc 'printf("%s\n", "Hello!");'  
  Hello!

So I figured I'd complement your example use with one that was more analogous to that.

> I can't edit my parent comment now, but it can be improved with e.g.

To be honest, I liked your original example more. Using that `//` "shebang" depends on what shell it's invoked from, and it wouldn't work when calling exec from other languages. For example, with your last example using `//`:

  $ python -c 'import subprocess; subprocess.run(["./hello-tcc-double-slash-shebang.c"])'   
  Traceback (most recent call last):
    File "<string>", line 1, in <module>
    File "/usr/lib/python3.8/subprocess.py", line 489, in run
      with Popen(*popenargs, **kwargs) as process:
    File "/usr/lib/python3.8/subprocess.py", line 854, in __init__
      self._execute_child(args, executable, preexec_fn, close_fds,
    File "/usr/lib/python3.8/subprocess.py", line 1702, in _execute_child
      raise child_exception_type(errno_num, err_msg, err_filename)
  OSError: [Errno 8] Exec format error: './hello-tcc-double-slash-shebang.c'

while it would work with the `#!` shebang, since that's handled by the kernel.