Intel® Fortran Compiler 18.0 Developer Guide and Reference
General Compiler Directives: DECLARE generates warnings for variables that have been used but have not been declared (like the IMPLICIT NONE statement). NODECLARE (the default) disables these warnings.
!DIR$ DECLARE
!DIR$ NODECLARE
The DECLARE directive is primarily a debugging tool that locates variables that have not been properly initialized, or that have been defined but never used.