https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83064
--- Comment #14 from Christian Felter <cfztol at hotmail dot com> --- I looked into the working draft of Fortran 2015 (J3/16-007r1). In Note 12.52 it says: The above constraints are designed to guarantee that a pure procedure is free from side effects (modifications of data visible outside the procedure), which means that it is safe to reference it in constructs such as DO CONCURRENT and FORALL, where there is no explicit order of evaluation. <...more text skipped...> From that I believe that the test program is valid Fortran.
