https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119136
--- Comment #10 from Jerry DeLisle <jvdelisle at gcc dot gnu.org> --- I looking around in libgfortran/io I found a file called lock.c. At the top of this file is a comment: /* Thread/recursion locking ... The content of the file is very short and it contains no obvious locking mechanism though I can see how we might do this. The file was created in 2004. Thus, "we" have been aware of this requirement since the creation of the universe. I think this will be a good place to put a check. We do have to be careful of the asynchronous I/O implemented elsewhere. I will be thinking on this.
