Cmake naming patterns for Fortran submodules inconsistent with cce/19 and cce/20 in buildtools EasyConfig

[gregordecristoforo]

The EasyConfig for the buildtools module downloads Cmake source code that doesn't have the correct filename extension for Fortran submodules with cce/19.0.0 and cce/20.0.0 compilers.

The problem is likely in '/appl/lumi/SW/LUMI-25.03/common/EB/buildtools/25.03/share/cmake-3.31/Modules/Compiler/Cray-Fortran.cmake', lines 7-8 with
'set(CMAKE_Fortran_SUBMODULE_SEP "")' and
'set(CMAKE_Fortran_SUBMODULE_EXT ".mod")'.
These settings work with cce/17.0.1, where submodules are named '.mod'.
In cce19 and 20 however, the naming convention is changed to '..smod'.

See ticket #7697 for more details.

Providing a patch file with something like the following might work:

--- Modules/Compiler/Cray-Fortran.cmake.orig   2023-10-01 12:00:00.000000000 +0000
+++ Modules/Compiler/Cray-Fortran.cmake        2023-10-01 12:00:00.000000000 +0000
@@ -6,8 +6,14 @@
 # Cray Fortran Compiler
 set(CMAKE_Fortran_COMPILER_ID_RUN 1)
 set(CMAKE_Fortran_SUBMODULE_SEP "")
-set(CMAKE_Fortran_SUBMODULE_EXT ".mod")
+set(CMAKE_Fortran_SUBMODULE_EXT ".mod") # Default for older versions
+# Adjust for CCE 19.0.0 and above
+if(CMAKE_Fortran_COMPILER_VERSION VERSION_GREATER_EQUAL 19.0.0)
+  set(CMAKE_Fortran_SUBMODULE_SEP "." CACHE STRING "submodule separator" FORCE)
+  set(CMAKE_Fortran_SUBMODULE_EXT ".smod" CACHE STRING "submodule extension" FORCE)
+endif()
+
 set(CMAKE_Fortran_FORMAT_FIXED_FLAG "-ffixed-form")
 set(CMAKE_Fortran_FORMAT_FREE_FLAG "-ffree-form")

[klust]

It would be good to have some not too large codes where this occur to test on.

[klust]

Looks like the compiler version is known already at that point as it is also used elsewhere in that file, and that the file is indeed only for cce Fortran so it should be relatively safe to change.

Likely solution: Replace

set(CMAKE_Fortran_SUBMODULE_SEP "")
set(CMAKE_Fortran_SUBMODULE_EXT ".mod")

with

if (NOT CMAKE_Fortran_COMPILER_VERSION VERSION_LESS 18.0.1)
  set(CMAKE_Fortran_SUBMODULE_SEP ".")
  set(CMAKE_Fortran_SUBMODULE_EXT ".smod")
else()
  set(CMAKE_Fortran_SUBMODULE_SEP "")
  set(CMAKE_Fortran_SUBMODULE_EXT ".mod")
endif()

The only question is when exactly this changed. We have 18.0.1 in a container though I haven't tested that one after the January 2026 update. We never had cce/18.0.0 which was in 24.07. We should probably take the older container into account also.

[klust]

And I did note that the issue is not solved yet in even the newest version of CMake. Looks like HPE should collaborate a bit closer with the CMake developers...

[alazzaro]

The name convention changed starting from cce/18.0.1.
Another problem has been fixed in CCE 20 (which is yet a new convention with respect to CCE 18.0.0 and lower).
The change should be added to Modules/Compiler/Cray-Fortran.cmake.

PE doesn't support CMake, it is up to the cmake users to support it :(

CC @tlunttl

[klust]

What is the exact change in CCE 20? For a very simple test example I did not note a difference in the naming scheme.

[alazzaro]

What is the exact change in CCE 20? For a very simple test example I did not note a difference in the naming scheme.

Sorry, my comment was confusing: it was a fix on capital VS lower letters (which is fixed with -ef). Nothing related to cmake.