Fortran 2018 (ISO/IEC 1539:2018) is the most recent version of the Fortran language standard. GNU Fortran implements some of the new features of this standard:

• All Fortran 2018 features derived from ISO/IEC TS 29113:2012, “Further Interoperability of Fortran with C”, are supported by GNU Fortran. This includes assumed-type and assumed-rank objects and the SELECT RANK construct as well as the parts relating to BIND(C) functions. See also Further Interoperability of Fortran with C.
• GNU Fortran supports a subset of features derived from ISO/IEC TS 18508:2015, “Additional Parallel Features in Fortran”:
  • The new atomic ADD, CAS, FETCH and ADD/OR/XOR, OR and XOR intrinsics.
  • The CO_MIN and CO_MAX and SUM reduction intrinsics, and the CO_BROADCAST and CO_REDUCE intrinsic, except that those do not support polymorphic types or types with allocatable, pointer or polymorphic components.
  • Events (EVENT POST, EVENT WAIT, EVENT_QUERY).
  • Failed images (FAIL IMAGE, IMAGE_STATUS, FAILED_IMAGES, STOPPED_IMAGES).
• An ERROR STOP statement is permitted in a PURE procedure.
• GNU Fortran supports the IMPLICIT NONE statement with an implicit-none-spec-list.
• The behavior of the INQUIRE statement with the RECL= specifier now conforms to Fortran 2018.