If I run ./configure.developer and then make and don't have flex installed, I get the following error:


Build failed                                                                                  
Traceback (most recent call last):                                                            
  File "/home/asn/workspace/projects/samba/third_party/waf/waflib/Context.py", line 452, in cmd_and_log
    ret, out, err = Utils.run_process(cmd, kw, cargs)             
  File "/home/asn/workspace/projects/samba/third_party/waf/waflib/Utils.py", line 992, in run_process
    return run_prefork_process(cmd, kwargs, cargs)
  File "/home/asn/workspace/projects/samba/third_party/waf/waflib/Utils.py", line 927, in run_prefork_process
    raise Exception(trace)
Exception: ['--noline', '../../source4/heimdal/lib/com_err/lex.l']
Traceback (most recent call last):                                                                                                                                                           
  File "<string>", line 37, in run
  File "/usr/lib64/python3.8/subprocess.py", line 854, in __init__
    self._execute_child(args, executable, preexec_fn, close_fds,               
  File "/usr/lib64/python3.8/subprocess.py", line 1702, in _execute_child                                                                                                                    
    raise child_exception_type(errno_num, err_msg, err_filename) 
FileNotFoundError: [Errno 2] No such file or directory: '--noline'


configure should check for flex and abort if it isn't installed in heimdal case.