dd4hep_add_dictionary fails when INTERFACE_COMPILE_DEFINITIONS contains COMPILE_LANGUAGE cmake genex

[wdconinc]

Check duplicate issues.

• Checked for duplicates

Goal

I have Geant4 compiled with TiMemory profiling (GEANT4_USE_TIMEMORY=ON), and I use this Geant4 version to compile DD4hep (DD4HEP_USE_GEANT4=ON). The compile definitions and options from TiMemory contain $<COMPILE_LANGUAGE:CXX> generator expressions in their CMake config files. These generator expressions are not accepted in all contexts 1, in particular not in the add_custom_command that is used to call rootcling in dd4hep_add_dictionary 2.

Operating System and Version

Ubuntu 23.10

compiler

gcc 13.2.0

ROOT Version

6.30.04

DD4hep Version

master c72c530

Reproducer

1. Install TiMemory and Geant4. I used TiMemory@develop and Geant4@11.2.1 in spack with the PR geant4: new variant timemory spack/spack#43111, but doing this 'by hand' should work as well.

$ spack install geant4 +timemory ^timemory@develop

2. Configure DD4hep to use Geant4:

$ cmake -Bbuild -S. -DDD4HEP_USE_GEANT4:BOOL=ON -DDD4HEP_DEBUG_CMAKE:BOOL=ON --fresh

This returns the dd4hep-configure-log.txt The recurring error message is:

CMake Error at cmake/DD4hepBuild.cmake:596 (add_custom_command):
  Error evaluating generator expression:

    $<COMPILE_LANGUAGE:CXX>

  $<COMPILE_LANGUAGE:...> may only be used to specify include directories,
  compile definitions, compile options, and to evaluate components of the
  file(GENERATE) command.
Call Stack (most recent call first):
  DDDigi/CMakeLists.txt:56 (dd4hep_add_dictionary)

Additional context

I've tried a few things, without luck:

• using $<TARGET_GENEX_EVAL:tgt,expr> around the relevant expressions, but this still didn't work
• using string(GENEX_STRIP) seems too aggressive
• using file(GENERATE) to write the command in a script and then call that script: this doesn't evaluate the CMake variables

I think the last option seemed most promising.

[wdconinc]

A sufficient workaround (but not a fix) for now appears to be:

diff --git a/cmake/DD4hepBuild.cmake b/cmake/DD4hepBuild.cmake
index ef84a22d..33b86710 100644
--- a/cmake/DD4hepBuild.cmake
+++ b/cmake/DD4hepBuild.cmake
@@ -574,7 +574,11 @@ function(dd4hep_add_dictionary dictionary )
     # Get INCLUDE DIRECTORIES from Dependencies
     LIST(APPEND inc_dirs $<TARGET_PROPERTY:${DEP},INTERFACE_INCLUDE_DIRECTORIES>)
     # Get COMPILE DEFINITIONS from Dependencies
-    LIST(APPEND comp_defs $<TARGET_PROPERTY:${DEP},INTERFACE_COMPILE_DEFINITIONS>)
+    if (NOT ${DEP} MATCHES "Geant4::Interface" AND NOT ${DEP} MATCHES "DD4hep::DDG4")
+      LIST(APPEND comp_defs $<TARGET_PROPERTY:${DEP},INTERFACE_COMPILE_DEFINITIONS>)
+    else()
+      message(STATUS "${DEP} INTERFACE_COMPILE_DEFINITIONS skipped")
+    endif()
   endforeach()
 
   #

[andresailer]

• file(GENERATE doesn't have COMMAND_EXPAND_LISTS, so the genex to join definitions etc. doesn't work
• In my debug build timemory defines DEBUG which clashes with a DEBUG enum in dd4hep

FAILED: DD4hep/DDG4/G__DDG4.cxx DD4hep/lib/G__DDG4_rdict.pcm /home/sailer/software/MetaMarlin/build103/DD4hep/DDG4/G__DDG4.cxx /home/sailer/software/MetaMarlin/build103/DD4hep/lib/G__DDG4_rdict.pcm 
cd /home/sailer/software/MetaMarlin/build103/DD4hep/DDG4 && /bin/bash fixed_create_G__DDG4_DebugCXX.sh
In file included from input_line_8:32:
In file included from /home/sailer/software/MetaMarlin/DD4hep/DDG4/include/DDG4/Geant4Config.h:102:
In file included from /home/sailer/software/MetaMarlin/DD4hep/DDG4/include/DDG4/Geant4Kernel.h:17:
In file included from /home/sailer/software/MetaMarlin/DD4hep/DDG4/include/DDG4/Geant4ActionContainer.h:17:
In file included from /cvmfs/sft.cern.ch/lcg/views/LCG_103/x86_64-centos7-gcc11-opt/include/DD4hep/Printout.h:21:
/cvmfs/sft.cern.ch/lcg/views/LCG_103/x86_64-centos7-gcc11-opt/include/Parsers/Printout.h:41:5: error: expected identifier
    DEBUG    = 2,
    ^
<command line>:4:15: note: expanded from here
#define DEBUG 1

• Can you please try with dd4hep_add_dictionary: use temporary file to create dictionary, needed for reasons (was 'Args') #1241