Reentrant yy_scan_string impossible?

[Bart Kus]

 Hello,

Using flex 2.5.35 and bison 2.4.2.  Setting up a yy_scan_string() like so:

    yyscan_t scanner;
    clilex_init(&scanner);
    YY_BUFFER_STATE lex_buff = cli_scan_string(cmd, scanner);
    if(cliparse(*this))
        clierror(*this, cmd);
    cli_delete_buffer(lex_buff, scanner);
    clilex_destroy(scanner);

Prefix="cli" for both flex and bison.  Get a segfault on first operation 
tried.  When running through gdb, the fault is hit in the flex code, but 
it seems like a user issue, or less likely, a bison design issue.  
cliparse() calls clilex() with what seems like its own yyscanner 
variable.  Looking at the call syntax, there's no place in where I tell 
cliparse(), "hey, use this yyscanner when talking to clilex".  It's 
probably just trying to read from yyin, instead of processing my buffer.

How do I tell bison about my custom flex scanner instance?

--Bart