Migrate idfupd.F90 from integer-packed datetime to ESMF_Time (MAPL3 migration)

[tclune]

Summary

As part of the MAPL3 migration, MAPL_UnpackDateTime (and all legacy integer-packed time) is being removed from MAPL_Base (tracked in GEOS-ESM/MAPL#4805 and GEOS-ESM/MAPL#4811). idfupd.F90 must be updated to use ESMF_Time directly — no integer-packed datetime should remain.

File

src/Applications/@GEOSgcm_App/idfupd.F90

Background

idfupd.F90 uses MAPL_GetResource to read 2-element integer arrays (datetime(2)) from RC files and from the cap_restart file, where datetime(1) is YYYYMMDD and datetime(2) is HHMMSS. It then calls MAPL_UnpackDateTime to extract the individual components (yy, mm, dd, h, m, s) before passing them to ESMF_TimeSet.

There are 4 call sites (lines ~540, ~565, ~595, ~698).

Change needed

The goal is to eliminate the integer datetime(2) intermediate entirely and work with ESMF_Time directly:

1. For RC file resources (BEG_DATE:, END_DATE:, JOB_SGMT:/JOB_DURATION:): Replace MAPL_GetResource(..., datetime, label=...) + MAPL_UnpackDateTime + ESMF_TimeSet with a direct read of an ISO8601 datetime string using MAPL_GetResource (string overload) and ESMF_TimeSet string interface — or read year/month/day/hour/minute/second components individually as already done in the fallback branches below each if(STATUS==ESMF_SUCCESS) block, and use ESMF_TimeSet(yy=...,mm=...,dd=...,h=...,m=...,s=...) directly.

2. For cap_restart file (line ~695-698): The file is read as read(UNIT,100) datetime with format (i8.8,1x,i6.6). Replace with reading the two integers directly into component variables and calling ESMF_TimeSet with keyword arguments — or update the restart format to ISO8601 if the broader team agrees.

3. Remove integer :: datetime(2), all MAPL_UnpackDateTime calls, and the corresponding use of MAPL_UnpackDateTime.

Note

The fallback branches (individual BEG_YY:, BEG_MM:, etc. resource items) already use the right pattern — the MAPL_UnpackDateTime branches should be brought in line with those.

Blocks

GEOS-ESM/MAPL#4811 (deletion of MAPL_UnpackDateTime from Base_Base.F90)