To: J3                                                     J3/25-155
From: Lorri Menard
Subject: US11 - Provide intrinsics for source location
Date: 2025-June-24

Reference: 23-193r1

I  Introduction

Paper 23-193r1 notes that users have requested a way to get the source
name and source line in their programs, as well as the current
procedure name.  Uses for this would be for debugging, for
logging purposes, etc.

The source name and source line request is being addressed in the
preprocessor work via __FILE__ and __LINE__ respectively.  However
the preprocessor would not be able to determine the current procedure
name without actually parsing the program itself.

There was a question raised earlier as to whether a run-time routine
would be useful when a template was instantiated, to at least point back
to the instantiation line itself.  Further investigation showed that
this would not be possible without a stack-trace facility, since an
implementation may (likely) create only a single routine called from
each identical instantiation within the entire set of files for a
program.

This paper addresses only the request for getting the current
procedure name.

II Specifications

PROCEDURE_NAME()
Description: Processor-dependent string that describes the name of the
             current procedure being executed or the current program
             unit if it appears in the specification section.
             If the program unit is an unnamed main program, the result
             is processor-dependent.

Class: Transformational function
Argument: None
Result Characteristics: Default character scalar with processor-dependent
                        length

Examples for PROCEDURE_NAME():

! For a module procedure
MODULE MYMOD
CHARACTER*(*), PARAMETER :: mymod_name = PROCEDURE_NAME()
                           ! Might become MYMOD
contains
   subroutine mymod_sub1
   character(*), PARAMETER, &
       private :: myname = mymod_name // "::" // PROCEDURE_NAME()
   print *, myname        ! Might print MYMOD::MYMOD_SUB1
   end subroutine mymod_sub1
end module mymod

! For an unnamed program
print *, PROCEDURE_NAME() ! Processor dependent output

! For a named program
PROGRAM EXAMPLE3
print *, PROCEDURE_NAME() ! Might print EXAMPLE3

! For a templated procedure
PROGRAM EXAMPLE4
    TEMPLATE iterate_tmpl(T)
       PRIVATE
       CHARACTER*(*), PARAMETER :: mytempl_name = PROCEDURE_NAME()
                                 ! Might become ITERATE_TEMPL
       PUBLIC :: iterate
       DEFERRED TYPE :: T
    CONTAINS
       SUBROUTINE iterate(x)
          TYPE(T), INTENT(INOUT) :: x
          character(*), PARAMETER, &
           private :: myname = mytempl_name // "::" // PROCEDURE_NAME()
          print *, "My name is ", PROCEDURE_NAME()
          print *, "but my full name is ", myname
       END SUBROUTINE iterate