Created attachment 396 [details]
CMake file

Hi,
I build geant4 10.2.1 with external CLHEP 2.3.1.1. the building is successful. I get a Geant4Config.cmake that contains the path to CLHEP

273 # Builtin/External packages
274 set(Geant4_builtin_clhep_FOUND )
275 if(NOT Geant4_builtin_clhep_FOUND)
276   set(Geant4_system_clhep_ISGRANULAR OFF)
277 
278   set(CLHEP_ROOT_DIR "/Users/mpetric/Desktop/CI/clhep-2.3.1.1")
279   find_package(CLHEP 2.3.1.1 REQUIRED )
280   unset(CLHEP_ROOT_DIR)
281   #CLHEP doesn't use target properties fully yet, so always include_directories
282   include_directories(${CLHEP_INCLUDE_DIRS})
283 endif()

So at this point geant knows where CLHEP is and I don't in practice need to worry about this if I use include(${Geant4_USE_FILE}).

However I observe a rather strange behavior. I have attached the CMakeList.txt and I am trying to build a simple example.cpp containing only
===== example.cpp
#include <CLHEP/Matrix/Matrix.h>
int main(int argc,char** argv) {
    CLHEP::HepMatrix a;
    return 0;
}
=====


We first have an empty environment then we source __path_to__/geant4.10.02.p01/bin/geant4.sh and then execute cmake on the attached CMakeList which results in cmake --trace-expand complaining

=======================================================================================================================
/Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake(261):  list(GET _g4dataset_tuple 2 Geant4_DATASET_G4ENSDFSTATE_PATH )
/Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake(263):  unset(Geant4_DATASET_DESCRIPTIONS )
/Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake(274):  set(Geant4_builtin_clhep_FOUND )
/Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake(275):  if(NOT Geant4_builtin_clhep_FOUND )
/Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake(276):  set(Geant4_system_clhep_ISGRANULAR OFF )
/Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake(278):  set(CLHEP_ROOT_DIR /Users/mpetric/Desktop/CI/clhep-2.3.1.1 )
/Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake(279):  find_package(CLHEP 2.3.1.1 REQUIRED )
CMake Error at /Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake:279 (find_package):
  By not providing "FindCLHEP.cmake" in CMAKE_MODULE_PATH this project has
  asked CMake to find a package configuration file provided by "CLHEP", but
  CMake did not find one.

  Could not find a package configuration file provided by "CLHEP" (requested
  version 2.3.1.1) with any of the following names:

    CLHEPConfig.cmake
    clhep-config.cmake

  Add the installation prefix of "CLHEP" to CMAKE_PREFIX_PATH or set
  "CLHEP_DIR" to a directory containing one of the above files.  If "CLHEP"
  provides a separate development package or SDK, be sure it has been
  installed.
Call Stack (most recent call first):
  CMakeLists.txt:4 (find_package)

=======================================================================================================================

So the cmake sets set(CLHEP_ROOT_DIR /Users/mpetric/Desktop/CI/clhep-2.3.1.1 ) but the find package does find clhep?

The only way I get this to work is to add clhep-2.3.1.1/bin to the PATH, but then find_package automatically searches in the directories 
=============
<prefix>/                                               (W)
<prefix>/(cmake|CMake)/                                 (W)
<prefix>/<name>*/                                       (W)
<prefix>/<name>*/(cmake|CMake)/                         (W)
<prefix>/(lib/<arch>|lib|share)/cmake/<name>*/          (U)
<prefix>/(lib/<arch>|lib|share)/<name>*/                (U)
<prefix>/(lib/<arch>|lib|share)/<name>*/(cmake|CMake)/  (U)
=============
https://cmake.org/cmake/help/v3.0/command/find_package.html


This can also be seen from the cmake trace


=======================================================================================================================
/Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake(274):  set(Geant4_builtin_clhep_FOUND )
/Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake(275):  if(NOT Geant4_builtin_clhep_FOUND )
/Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake(276):  set(Geant4_system_clhep_ISGRANULAR OFF )
/Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake(278):  set(CLHEP_ROOT_DIR /Users/mpetric/Desktop/CI/clhep-2.3.1.1 )
/Users/mpetric/Desktop/CI/geant4.10.02.p01/lib/Geant4-10.2.1/Geant4Config.cmake(279):  find_package(CLHEP 2.3.1.1 REQUIRED )
/Users/mpetric/Desktop/CI/clhep-2.3.1.1/lib/CLHEP-2.3.1.1/CLHEPConfigVersion.cmake(12):  set(PACKAGE_VERSION 2.3.1.1 )
/Users/mpetric/Desktop/CI/clhep-2.3.1.1/lib/CLHEP-2.3.1.1/CLHEPConfigVersion.cmake(15):  if(2.3.1.1 VERSION_LESS 2.3.1.1 )
/Users/mpetric/Desktop/CI/clhep-2.3.1.1/lib/CLHEP-2.3.1.1/CLHEPConfigVersion.cmake(17):  else()
/Users/mpetric/Desktop/CI/clhep-2.3.1.1/lib/CLHEP-2.3.1.1/CLHEPConfigVersion.cmake(18):  set(PACKAGE_VERSION_COMPATIBLE TRUE )
/Users/mpetric/Desktop/CI/clhep-2.3.1.1/lib/CLHEP-2.3.1.1/CLHEPConfigVersion.cmake(19):  if(2.3.1.1 VERSION_EQUAL 2.3.1.1 )
/Users/mpetric/Desktop/CI/clhep-2.3.1.1/lib/CLHEP-2.3.1.1/CLHEPConfigVersion.cmake(20):  set(PACKAGE_VERSION_EXACT TRUE )
=======================================================================================================================


However the FindCLHEP.cmake provided in geant in lib/Geant4-10.2.1/Modules/FindCLHEP.cmake is never used?


So the question is weather there is a bug in the geant cmake or how to properly setup cmake for my project so that using only include(${Geant4_USE_FILE}) I will get the same clhep as geant was build with?

Cheers,
Marko