[CMake] Make non-system include paths accessible at runtime

The current implementation faces issues with accessing header files
from external libraries stored in non-system paths when the C++
interpreter tries to resolve them at runtime. This access is necessary
under certain conditions even if a corresponding module file exists.

To address this issue, we need to ensure that non-system path includes,
which are known at build time, remain accessible at runtime. The
proposed solution leverages the existing `ROOT_INCLUDE_PATH` environment
variable.

This commit introduces a new CMake variable `DEFAULT_ROOT_INCLUDE_PATH`
and a helper function `BUILD_ROOT_INCLUDE_PATH`. This function allows
us to append include paths of external libraries to `BUILD_ROOT_INCLUDE_PATH`,
for example:
`DEFAULT_ROOT_INCLUDE_PATH("${Vc_INCLUDE_DIR}" DEFAULT_ROOT_INCLUDE_PATH)`

The `DEFAULT_ROOT_INCLUDE_PATH` variable is then utilized to populate the
`ROOT_INCLUDE_PATH` environment variable in the configuration files
(`thisroot.{sh,csh,fish,bat}`).

If the library's include path is dynamically modified between build and
run time, the configuration can be updated by patching the
`thisroot.{sh,csh,fish,bat}` files.

Author: LukasBreitwieser

CMakeLists.txt

@@ -548,10 +548,6 @@ install(
    PATTERN "pkgconfig" EXCLUDE
 )
 
-if(Vc_INCLUDE_DIR)
-  set(MODULES_ROOT_INCPATH "ROOT_INCLUDE_PATH=${Vc_INCLUDE_DIR}:${ROOT_INCLUDE_PATH}")
-endif()
-
 # modules.idx
 if(runtime_cxxmodules)
   ROOT_GET_LIBRARY_OUTPUT_DIR(library_output_dir)
@@ -561,6 +557,7 @@ if(runtime_cxxmodules)
                                 ROOTIGNOREPREFIX=1 ROOT_HIST=0 $<TARGET_FILE:root.exe> -l -q -b)
   else()
     set(modules_idx_cmd COMMAND ${ld_library_path}=${library_output_dir}:$ENV{${ld_library_path}}
+                                ROOT_INCLUDE_PATH=${DEFAULT_ROOT_INCLUDE_PATH}
                                 ROOTIGNOREPREFIX=1 ROOT_HIST=0 $<TARGET_FILE:root.exe> -l -q -b)
   endif()
   add_custom_command(OUTPUT ${library_output_dir}/modules.idx
@@ -582,9 +579,10 @@ add_custom_target(hsimple ALL DEPENDS tutorials/hsimple.root)
 add_dependencies(hsimple onepcm)
 if(WIN32)
   set(hsimple_cmd COMMAND ${CMAKE_COMMAND} -E env PATH="${CMAKE_RUNTIME_OUTPUT_DIRECTORY}\\\;%PATH%"
+                          ROOT_INCLUDE_PATH="${DEFAULT_ROOT_INCLUDE_PATH}"
                           ROOTIGNOREPREFIX=1 ROOT_HIST=0 $<TARGET_FILE:root.exe> -l -q -b -n -x ${CMAKE_SOURCE_DIR}/tutorials/hsimple.C -e return)
 else()
-  set(hsimple_cmd COMMAND ${MODULES_ROOT_INCPATH} ${ld_library_path}=${CMAKE_LIBRARY_OUTPUT_DIRECTORY}:$ENV{${ld_library_path}}
+  set(hsimple_cmd COMMAND ROOT_INCLUDE_PATH="${DEFAULT_ROOT_INCLUDE_PATH}" ${ld_library_path}=${CMAKE_LIBRARY_OUTPUT_DIRECTORY}:$ENV{${ld_library_path}}
                           ROOTIGNOREPREFIX=1 ROOT_HIST=0 $<TARGET_FILE:root.exe> -l -q -b -n -x ${CMAKE_SOURCE_DIR}/tutorials/hsimple.C -e return)
 endif()
 add_custom_command(OUTPUT tutorials/hsimple.root

cmake/modules/RootMacros.cmake

@@ -2114,6 +2114,49 @@ function(ROOT_APPEND_LIBDIR_TO_INSTALL_RPATH target install_dir)
   set_property(TARGET ${target} APPEND PROPERTY INSTALL_RPATH "${new_rpath}")
 endfunction()
 
+#----------------------------------------------------------------------------
+# If path is a system include path, set the return variable
+# is_system_include_path to true.
+# The 1st argument is the path that should be checked
+# The 2nd argument is the return value
+#----------------------------------------------------------------------------
+function (IS_SYSTEM_INCLUDE_PATH path is_system_include_path)
+  foreach (dir ${CMAKE_SYSTEM_INCLUDE_PATH})
+    if ("${path}" STREQUAL "${dir}")
+      set(${is_system_include_path} TRUE PARENT_SCOPE)
+      return()
+    endif()
+  endforeach()
+  set(${is_system_include_path} FALSE PARENT_SCOPE)
+endfunction()
+
+#----------------------------------------------------------------------------
+# Include paths of third-party libraries stored outside of system directories
+# must be added to the DEFAULT_ROOT_INCLUDE_PATH variable to ensure that the
+# C++ interpreter 'cling' can locate these header files at runtime.
+# Use this function to add these paths to DEFAULT_ROOT_INCLUDE_PATH.
+#----------------------------------------------------------------------------
+function (BUILD_ROOT_INCLUDE_PATH path)
+  # filter out paths into the ROOT src, build, and install directories
+  if((${path} MATCHES "${CMAKE_SOURCE_DIR}(/.*)?") OR
+     (${path} MATCHES "${CMAKE_BINARY_DIR}(/.*)?") OR
+     (${path} MATCHES "${CMAKE_INSTALL_PREFIX}(/.*)?"))
+    return()
+  endif()
+  IS_SYSTEM_INCLUDE_PATH("${path}" is_system_include_path)
+  if (NOT is_system_include_path)
+    if ("${DEFAULT_ROOT_INCLUDE_PATH}" STREQUAL "")
+      set(DEFAULT_ROOT_INCLUDE_PATH "${path}" PARENT_SCOPE)
+    else()
+      if(WIN32)
+        set(ROOT_PATH_SEPARATOR ";")
+      elseif(UNIX)
+        set(ROOT_PATH_SEPARATOR ":")
+      endif()
+      set(DEFAULT_ROOT_INCLUDE_PATH "${DEFAULT_ROOT_INCLUDE_PATH}${ROOT_PATH_SEPARATOR}${path}" PARENT_SCOPE)
+    endif()
+  endif()
+endfunction()
 
 #-------------------------------------------------------------------------------
 #

cmake/modules/SearchInstalledSoftware.cmake

@@ -1383,6 +1383,7 @@ elseif(vc)
   endif()
   if(Vc_FOUND)
     set_property(DIRECTORY APPEND PROPERTY INCLUDE_DIRECTORIES ${Vc_INCLUDE_DIR})
+    BUILD_ROOT_INCLUDE_PATH("${Vc_INCLUDE_DIR}")
   endif()
 endif()
 
@@ -1616,6 +1617,8 @@ if(vdt OR builtin_vdt)
     install(DIRECTORY ${CMAKE_BINARY_DIR}/include/vdt
             DESTINATION ${CMAKE_INSTALL_INCLUDEDIR} COMPONENT extra-headers)
     set_property(GLOBAL APPEND PROPERTY ROOT_BUILTIN_TARGETS VDT::VDT)
+  else()
+    BUILD_ROOT_INCLUDE_PATH("${VDT_INCLUDE_DIR}")
   endif()
 endif()
 

config/thisroot.bat

@@ -12,5 +12,6 @@ cd /D %OLDPATH%
 set PATH=%ROOTSYS%\bin;%PATH%
 set CMAKE_PREFIX_PATH=%ROOTSYS%;%CMAKE_PREFIX_PATH%
 set PYTHONPATH=%ROOTSYS%\bin;%PYTHONPATH%
+set ROOT_INCLUDE_PATH=@DEFAULT_ROOT_INLUCDE_PATH@;%ROOT_INCLUDE_PATH%
 set OLDPATH=
 set THIS=

config/thisroot.csh

@@ -169,6 +169,14 @@ if ($?old_rootsys) then
                                  -e "s;^$old_rootsys/etc/notebook${DOLLAR};;g"`
    endif
 
+   if ($?ROOT_INCLUDE_PATH) then
+      setenv ROOT_INCLUDE_PATH `set DOLLAR='$'; echo $ROOT_INCLUDE_PATH | \
+                             sed -e "s;:@DEFAULT_ROOT_INCLUDE_PATH@:;:;g" \
+                                 -e "s;:@DEFAULT_ROOT_INCLUDE_PATH@${DOLLAR};;g"   \
+                                 -e "s;^@DEFAULT_ROOT_INCLUDE_PATH@:;;g"   \
+                                 -e "s;^@DEFAULT_ROOT_INCLUDE_PATH@${DOLLAR};;g"`
+   endif
+
 endif
 
 
@@ -239,6 +247,12 @@ else
    setenv JUPYTER_CONFIG_PATH ${ROOTSYS}/etc/notebook
 endif
 
+if ($?ROOT_INCLUDE_PATH) then
+   setenv ROOT_INCLUDE_PATH @DEFAULT_ROOT_INLUCDE_PATH@:$ROOT_INCLUDE_PATH
+else
+   setenv ROOT_INCLUDE_PATH @DEFAULT_ROOT_INLUCDE_PATH@
+endif
+
 endif # if ("$thisrootdir" != "")
 
 set thisrootdir=

config/thisroot.fish

@@ -55,6 +55,7 @@ update_path MANPATH "$old_rootsys" "/man" @mandir@
 update_path CMAKE_PREFIX_PATH "$old_rootsys" "" $ROOTSYS
 update_path JUPYTER_PATH "$old_rootsys" "/etc/notebook" $ROOTSYS/etc/notebook
 update_path JUPYTER_CONFIG_PATH "$old_rootsys" "/etc/notebook" $ROOTSYS/etc/notebook
+update_path ROOT_INCLUDE_PATH "@DEFAULT_ROOT_INCLUDE_PATH@" "" "@DEFAULT_ROOT_INCLUDE_PATH@"
 
 functions -e update_path
 set -e old_rootsys

config/thisroot.ps1

@@ -7,3 +7,4 @@ $ROOTSYS = split-path -parent (get-item $scriptPath)
 $env:PATH = $ROOTSYS + '\bin;' + $env:PATH
 $env:CMAKE_PREFIX_PATH = $ROOTSYS + ';' + $env:CMAKE_PREFIX_PATH
 $env:PYTHONPATH = $ROOTSYS + '\bin;' + $env:PYTHONPATH
+$env:ROOT_INCLUDE_PATH = "@DEFAULT_ROOT_INCLUDE_PATH@" + ';' + $env:ROOT_INCLUDE_PATH

config/thisroot.sh

@@ -89,6 +89,10 @@ clean_environment()
          default_manpath=""
       fi
    fi
+   if [ -n "${ROOT_INCLUDE_PATH-}" ]; then
+      drop_from_path "$ROOT_INCLUDE_PATH" "@DEFAULT_ROOT_INCLUDE_PATH@"
+      ROOT_INCLUDE_PATH=$newpath
+   fi
 }
 
 set_environment()
@@ -162,6 +166,14 @@ set_environment()
    else
       JUPYTER_CONFIG_PATH=$ROOTSYS/etc/notebook:$JUPYTER_CONFIG_PATH; export JUPYTER_CONFIG_PATH
    fi
+
+   if [ -z "${ROOT_INCLUDE_PATH-}" ]; then
+      ROOT_INCLUDE_PATH=@DEFAULT_ROOT_INCLUDE_PATH@
+      export ROOT_INCLUDE_PATH
+   else
+      ROOT_INCLUDE_PATH=@DEFAULT_ROOT_INCLUDE_PATH@:$ROOT_INCLUDE_PATH
+      export ROOT_INCLUDE_PATH
+   fi
 }
 
 getTrueShellExeName() { # mklement0 https://stackoverflow.com/a/23011530/7471760

roottest/root/io/transient/base/CMakeLists.txt

@@ -23,4 +23,4 @@ ROOTTEST_ADD_TEST(hadd_autoload
                   COMMAND hadd -f data_merge.root data1.root data2.root
                   OUTREF hadd_autoload${outref_suffix}.ref
                   FIXTURES_REQUIRED root-io-transient-base-WriteFile-fixture
-                  ENVIRONMENT ROOT_INCLUDE_PATH=${CMAKE_CURRENT_SOURCE_DIR})
+                  ENVIRONMENT ROOT_INCLUDE_PATH=${CMAKE_CURRENT_SOURCE_DIR}:${DEFAULT_ROOT_INCLUDE_PATH})

roottest/root/meta/countIncludePaths.C

@@ -17,9 +17,18 @@ int countIncludePaths()
    // Exclude from the test the builds with R as external package
    if (std::string::npos != includePath.find("RInside/include")) return 0;
 
+   // count paths coming from the ROOT_INCLUDE_PATH environment variable
+   // and exclude them
+   int nEnvVarPaths = 0;
+   auto *envVarCStr = std::getenv("ROOT_INCLUDE_PATH");
+   if (envVarCStr) {
+      std::string envVar(envVarCStr);
+      nEnvVarPaths = countSubstring(envVar, ":") + 1 - (envVar.back() == ':') - (envVar.front() == ':');
+   }
+
    // At most 10
    auto nPaths = countSubstring(includePath, "-I");
-   if (nPaths > 10){
+   if ((nPaths - nEnvVarPaths) > 10) {
       std::cerr << "The number of include paths is too high (>9) " << nPaths
                 << ". The number of \"-I\"s has been counted in the include path of ROOT (gSystem->GetIncludePath()=" << includePath << ")." << std::endl;
       return nPaths;