Feature: Reintroduce FetchContent

.github/workflows/test_preparation.yml

@@ -68,10 +68,6 @@ jobs:
       # This seems to be necessary because of the docker container
     - name: disable ownership checks
       run: git config --global --add safe.directory '*'
-    - name: init submodules
-      run: git submodule init
-    - name: update submodules
-      run: git submodule update
     - name: Get input vars
       run: export MAKEFLAGS="${{ inputs.MAKEFLAGS }}"
         && export IGNORE_CACHE="${{ inputs.IGNORE_CACHE }}"
@@ -85,11 +81,16 @@ jobs:
 #       SC installation
 #
     - name: store sc folders in var
-      run: echo SC_BUILD=$PWD/sc/build >> $GITHUB_ENV
+      run: echo SC_SOURCE=$PWD/sc >> $GITHUB_ENV
+        && echo SC_BUILD=$PWD/sc/build >> $GITHUB_ENV
         && echo SC_DEBUG=$PWD/sc/build/Debug >> $GITHUB_ENV
         && echo SC_RELEASE=$PWD/sc/build/Release >> $GITHUB_ENV
-    - name: Get sc commit hash
-      run: hash=`git rev-parse HEAD:sc` && echo sc_commit=$hash >> $GITHUB_ENV
+    - name: Get sc commit hash  and url from thirdparty.json
+      run: |
+        hash=$(jq -r '.thirdparty[] | select(.name=="SC") .source.ref' cmake/thirdparty.json)
+        echo sc_commit=$hash >> $GITHUB_ENV
+        url=$(jq -r '.thirdparty[] | select(.name=="SC") .source.url' cmake/thirdparty.json)
+        echo sc_url=$url >> $GITHUB_ENV
     - name: Check cache for previous sc installation
       id: sc_cmake_cache
       uses: actions/cache@v5
@@ -109,22 +110,29 @@ jobs:
       if: ${{ inputs.IGNORE_CACHE == 1 }}
       # The true at the end is to ignore errors that i.e. occur when the folders do not exist
       run: rm -r $SC_BUILD || true
-    - name: make folders
-      run: mkdir -p $SC_DEBUG $SC_RELEASE
-      if: ${{ steps.sc_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
     - name: install sc
       run: echo "Install sc"
       if: ${{ steps.sc_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
-      ## sc debug
+    - uses: actions/checkout@v6
+      with:
+        repository: cburstedde/libsc
+        ref: ${{ env.sc_commit }}
+        fetch-depth: 1
+        path: ${{ env.SC_SOURCE }}
+      if: ${{ steps.sc_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
+    - name: make folders
+      run: mkdir -p $SC_DEBUG $SC_RELEASE
+      if: ${{ steps.sc_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
+      ## sc debug build
     - name: sc cmake debug
-      run: cd $SC_DEBUG && cmake ../../ -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=$SC_DEBUG/install -Dmpi=$MPI -GNinja
+      run: cd $SC_DEBUG && cmake $SC_SOURCE -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=$SC_DEBUG/install -Dmpi=$MPI -GNinja
       if: ${{ steps.sc_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
     - name: sc build debug
       run: cd $SC_DEBUG && ninja $MAKEFLAGS && ninja $MAKEFLAGS install
       if: ${{ steps.sc_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
-      ## sc release
+      ## sc release build
     - name: sc cmake release
-      run: cd $SC_RELEASE && cmake ../../ -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$SC_RELEASE/install -Dmpi=$MPI -GNinja
+      run: cd $SC_RELEASE && cmake $SC_SOURCE -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$SC_RELEASE/install -Dmpi=$MPI -GNinja
       if: ${{ steps.sc_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
     - name: sc build release
       run: cd $SC_RELEASE && ninja $MAKEFLAGS && ninja $MAKEFLAGS install
@@ -133,11 +141,16 @@ jobs:
 # P4EST
 #
     - name: store p4est folders in var
-      run: echo P4EST_BUILD=$PWD/p4est/build >> $GITHUB_ENV
+      run: echo P4EST_SOURCE=$PWD/p4est >> $GITHUB_ENV
+        && echo P4EST_BUILD=$PWD/p4est/build >> $GITHUB_ENV
         && echo P4EST_DEBUG=$PWD/p4est/build/Debug >> $GITHUB_ENV
         && echo P4EST_RELEASE=$PWD/p4est/build/Release >> $GITHUB_ENV
-    - name: Get p4est commit hash
-      run: hash=`git rev-parse HEAD:p4est` && echo p4est_commit=$hash >> $GITHUB_ENV
+    - name: Get p4est commit hash and url from thirdparty.json
+      run: |
+        hash=$(jq -r '.thirdparty[] | select(.name=="P4EST") .source.ref' cmake/thirdparty.json)
+        echo p4est_commit=$hash >> $GITHUB_ENV
+        url=$(jq -r '.thirdparty[] | select(.name=="P4EST") .source.url' cmake/thirdparty.json)
+        echo p4est_url=$url >> $GITHUB_ENV
     - name: Check cache for previous p4est installation
       id: p4est_cmake_cache
       uses: actions/cache@v5
@@ -153,26 +166,33 @@ jobs:
     - name: Cache info
       if: ${{ steps.p4est_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
       run: echo No cache found or cache will be ignored. IGNORE_CACHE=$IGNORE_CACHE
-    - name: install p4est
-      run: echo "Install p4est"
-      if: ${{ steps.p4est_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
     - name: if ignore cache, delete folders
       if: ${{ steps.p4est_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
       # The true at the end is to ignore errors that i.e. occur when the folders do not exist
       run: rm -r $P4EST_BUILD || true
+    - name: install p4est
+      run: echo "Install p4est"
+      if: ${{ steps.p4est_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
+    - uses: actions/checkout@v6
+      with:
+        repository: cburstedde/p4est
+        ref: ${{ env.p4est_commit }}
+        fetch-depth: 1
+        path: ${{ env.P4EST_SOURCE }}
+      if: ${{ steps.p4est_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
     - name: make folders
       if: ${{ steps.p4est_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
       run: mkdir -p $P4EST_DEBUG $P4EST_RELEASE
-    ## p4est debug
+    ## p4est debug build
     - name: p4est cmake debug
-      run: cd $P4EST_DEBUG && cmake ../../ -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=$P4EST_DEBUG/install -DP4EST_USE_SYSTEM_SC=ON -DSC_DIR=$SC_DEBUG/install/cmake -DP4EST_ENABLE_MPI=$MPI -GNinja
+      run: cd $P4EST_DEBUG && cmake $P4EST_SOURCE -DCMAKE_BUILD_TYPE=Debug -DCMAKE_INSTALL_PREFIX=$P4EST_DEBUG/install -DP4EST_USE_SYSTEM_SC=ON -DSC_DIR=$SC_DEBUG/install/cmake -DP4EST_ENABLE_MPI=$MPI -GNinja
       if: ${{ steps.p4est_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
     - name: p4est build debug
       run: cd $P4EST_DEBUG && ninja $MAKEFLAGS && ninja $MAKEFLAGS install
       if: ${{ steps.p4est_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
-    ## p4est release
+    ## p4est release build
     - name: p4est cmake release
-      run: cd $P4EST_RELEASE && cmake ../../ -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$P4EST_RELEASE/install -DP4EST_USE_SYSTEM_SC=ON -DSC_DIR=$SC_DEBUG/install/cmake -DP4EST_ENABLE_MPI=$MPI -GNinja
+      run: cd $P4EST_RELEASE && cmake $P4EST_SOURCE -DCMAKE_BUILD_TYPE=Release -DCMAKE_INSTALL_PREFIX=$P4EST_RELEASE/install -DP4EST_USE_SYSTEM_SC=ON -DSC_DIR=$SC_RELEASE/install/cmake -DP4EST_ENABLE_MPI=$MPI -GNinja
       if: ${{ steps.p4est_cmake_cache.outputs.cache-hit != 'true' || inputs.IGNORE_CACHE == 1 }}
     - name: p4est build release
       run: cd $P4EST_RELEASE && ninja $MAKEFLAGS && ninja $MAKEFLAGS install

.github/workflows/test_t8code_w_shipped_submodules.yml

@@ -62,10 +62,6 @@ jobs:
       # This seems to be necessary because of the docker container
     - name: disable ownership checks
       run: git config --global --add safe.directory '*'
-    - name: init submodules
-      run: git submodule init
-    - name: update submodules
-      run: git submodule update
     - name: Get input vars
       run: export MAKEFLAGS="${{ inputs.MAKEFLAGS }}"
         && export MPI="${{ inputs.MPI }}"

.github/workflows/testsuite.yml

@@ -120,7 +120,7 @@ jobs:
     with:
       MAKEFLAGS: ${{ matrix.MAKEFLAGS }}
       IGNORE_CACHE: false # Use this to force a new installation of sc and p4est for this specific workflow run
-      CACHE_COUNTER: 0 # Increase this number to force a new installation of sc and p4est and to update the cache once
+      CACHE_COUNTER: 8 # Increase this number to force a new installation of sc and p4est and to update the cache once
       MPI: ${{ matrix.MPI }}
 
   # Run parallel tests for sc and p4est with and without MPI

CMakeLists.txt

@@ -2,7 +2,7 @@
 #  t8code is a C library to manage a collection (a forest) of multiple
 #  connected adaptive space-trees of general element types in parallel.
 #
-#  Copyright (C) 2025 the developers
+#  Copyright (C) 2026 the developers
 #
 #  t8code is free software; you can redistribute it and/or modify
 #  it under the terms of the GNU General Public License as published by
@@ -18,11 +18,9 @@
 #  along with t8code; if not, write to the Free Software Foundation, Inc.,
 #  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 
-cmake_minimum_required( VERSION 3.16 )
+cmake_minimum_required( VERSION 3.19 )
 
 include( cmake/GitProjectVersion.cmake )
-include( FetchContent )
-# All fetchcontent cmake options+ are marked as advanced below.
 
 project(
     T8CODE
@@ -35,18 +33,6 @@ include( GNUInstallDirs)
 include( CTest )
 include( CMakeDependentOption )
 
-FetchContent_Declare(
-    googletest
-    GIT_REPOSITORY "https://github.com/DLR-SC/googletest_mpi.git"
-    GIT_TAG 98bfff426b057400268a00f97677d749a9e25096 #v1.17.0_mpi
-    GIT_PROGRESS TRUE
-	GIT_SHALLOW TRUE
-    )
-
-set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
-mark_as_advanced( FORCE gtest_force_shared_crt)
-
-
 option( T8CODE_BUILD_AS_SHARED_LIBRARY "Whether t8code should be built as a shared or a static library" ON )
 option( T8CODE_BUILD_PEDANTIC "Compile t8code with `-pedantic` as done in the Github CI." OFF )
 option( T8CODE_BUILD_WALL "Compile t8code with `-Wall` as done in the Github CI." OFF )
@@ -124,17 +110,79 @@ if( T8CODE_ENABLE_MPI )
     else()
       find_package( MPI 3.0 COMPONENTS C REQUIRED )
     endif()
-    set (gtest_disable_mpi OFF CACHE BOOL "disable gtest mpi support" FORCE)
+    set (gtest_disable_mpi OFF CACHE INTERNAL "disable gtest mpi support" FORCE)
 
     if( NOT MPIEXEC_EXECUTABLE )
         message( FATAL_ERROR "MPIEXEC was not found" )
     endif()
-    set( SC_ENABLE_MPI ON )
+    set( SC_ENABLE_MPI ON CACHE INTERNAL "enable mpi support in libsc" FORCE)
+else()
+    set( gtest_disable_mpi ON CACHE INTERNAL "disable gtest mpi support" FORCE)
+endif()
+
+############################################ ThirdParty ############################################
+
+# Set some variables for the thirdparty libraries
+set(gtest_force_shared_crt ON CACHE INTERNAL "" FORCE)
+set( P4EST_BUILD_EXAMPLES ${T8CODE_BUILD_TPL_EXAMPLES} )
+set( P4EST_BUILD_TESTING ${T8CODE_BUILD_TPL_TESTS} )
+set( SC_BUILD_EXAMPLES ${T8CODE_BUILD_TPL_EXAMPLES} )
+set( SC_BUILD_TESTING ${T8CODE_BUILD_TPL_TESTS} )
+
+# When executing CMake tests for some thirdparty libraries like sc, i.e. check_c_source_compiles/check_cxx_source_compiles and others
+# we need to ignore the -Werror option, since these tests often produce warnings (see check_mpicommshared.cmake from sc for example).
+# If theses warnings are interpreted as errors, the test fails even though we want it to pass.
+# This behaviour caused a serious bug and did not initialize our shared memory. See https://github.com/DLR-AMR/t8code/issues/1985.
+set( T8CODE_OLD_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}" )
+if (WIN32 AND NOT MINGW)
+    set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} /w" )
+else()
+    set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -w" )
+endif()
+
+# Do the same for the normal build flags to suppress warnings from the thirdparty library
+set(ORIGINAL_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+set(ORIGINAL_C_FLAGS   "${CMAKE_C_FLAGS}")
+if (WIN32 AND NOT MINGW)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /w" CACHE STRING "" FORCE)
+    set(CMAKE_C_FLAGS   "${CMAKE_C_FLAGS}   /w" CACHE STRING "" FORCE)
 else()
-    set( gtest_disable_mpi ON CACHE BOOL "disable gtest mpi support" FORCE)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -w" CACHE STRING "" FORCE)
+    set(CMAKE_C_FLAGS   "${CMAKE_C_FLAGS}   -w" CACHE STRING "" FORCE)
 endif()
 
-mark_as_advanced( FORCE gtest_disable_mpi)
+# Capture the list of variables before adding the thirdparty libraries to mark the added ones as advanced.
+get_cmake_property(_vars_before_thirdparty VARIABLES )
+
+# Populate the thirdparty libraries
+include (cmake/thirdparty.cmake)
+
+# Capture the list of variables after adding thirdparty libraries
+get_cmake_property(_vars_after_thirdparty VARIABLES)
+
+# Find variables that exist after but not before
+set(_new_thirdparty_vars)
+foreach(_var IN LISTS _vars_after_thirdparty)
+    list(FIND _vars_before_thirdparty "${_var}" _index)
+    if(_index EQUAL -1)
+        list(APPEND _new_thirdparty_vars ${_var})
+    endif()
+endforeach()
+
+# Mark the new variables as advanced
+if(_new_thirdparty_vars)
+    mark_as_advanced(FORCE ${_new_thirdparty_vars})
+endif()
+
+# Reactivate previous CMAKE_REQUIRED_FLAGS and CMAKE_C/CXX_FLAGS
+set( CMAKE_REQUIRED_FLAGS "${T8CODE_OLD_CMAKE_REQUIRED_FLAGS}" )
+unset( T8CODE_OLD_CMAKE_REQUIRED_FLAGS )
+set(CMAKE_CXX_FLAGS "${ORIGINAL_CXX_FLAGS}" CACHE STRING "" FORCE)
+set(CMAKE_C_FLAGS   "${ORIGINAL_C_FLAGS}"   CACHE STRING "" FORCE)
+unset (ORIGINAL_CXX_FLAGS)
+unset (ORIGINAL_C_FLAGS)
+
+############################################ End of ThirdParty ############################################
 
 
 if( T8CODE_ENABLE_VTK )
@@ -183,39 +231,6 @@ endif()
 if ( T8CODE_USE_SYSTEM_SC )
     find_package( SC REQUIRED )
 else()
-    set( SC_BUILD_EXAMPLES ${T8CODE_BUILD_TPL_EXAMPLES} )
-    set( SC_BUILD_TESTING ${T8CODE_BUILD_TPL_TESTS} )
-
-    # When executing CMake tests for libsc, i.e. check_c_source_compiles/check_cxx_source_compiles and others
-    # we need to ignore the -Werror option, since these tests often produce warnings (see check_mpicommshared.cmake for example).
-    # If theses warnings are interpreted as errors, the test fails even though we want it to pass.
-    # This behaviour caused a serious bug and did not initialize our shared memory. See https://github.com/DLR-AMR/t8code/issues/1985.
-    set( T8CODE_OLD_CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS}" )
-    if (WIN32 AND NOT MINGW)
-        set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} /w" )
-    else()
-        set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -w" )
-    endif()
-
-    # Capture the list of variables before adding the subdirectory to mark the added ones as advanced.
-    get_cmake_property(_vars_before_sc VARIABLES )
-    list( APPEND CMAKE_MESSAGE_CONTEXT "sc" )
-    add_subdirectory( ${CMAKE_CURRENT_LIST_DIR}/sc )
-    list( POP_BACK CMAKE_MESSAGE_CONTEXT )
-    add_library(SC INTERFACE)
-    # Capture the list of variables after adding the subdirectory
-    get_cmake_property(_vars_after_sc VARIABLES )
-    # Compute the difference (new variables added by the subdirectory)
-    set( _new_sc_vars)
-    foreach( _var IN LISTS _vars_after_sc )
-        if( NOT _var IN_LIST _vars_before_sc )
-            list( APPEND _new_sc_vars ${_var} )
-        endif()
-    endforeach()
-
-    # Mark the new variables as advanced
-    mark_as_advanced( FORCE ${_new_sc_vars} )
-
     ########################## Fix for OpenMPI ############################################
     # OpenMPI sometimes has a mismatch between their C and CXX interface which produces a warning in SC.
     # The warning makes t8codes build fail when Werror is activated. This fix checks if t8code
@@ -247,63 +262,13 @@ else()
         message(WARNING "mpi.h not found!")
     endif()
     ########################## End of fix for OpenMPI ############################################
-
-    # Reactivate previous CMAKE_REQUIRED_FLAGS  
-    set( CMAKE_REQUIRED_FLAGS "${T8CODE_OLD_CMAKE_REQUIRED_FLAGS}" )
-    unset( T8CODE_OLD_CMAKE_REQUIRED_FLAGS )
 endif()
 
+
 if ( T8CODE_USE_SYSTEM_P4EST )
     find_package( P4EST REQUIRED )
-else()
-    set( P4EST_BUILD_EXAMPLES ${T8CODE_BUILD_TPL_EXAMPLES} )
-    set( P4EST_BUILD_TESTING ${T8CODE_BUILD_TPL_TESTS} )
-
-    # Capture the list of variables before adding the subdirectory to mark the added ones as advanced.
-    get_cmake_property( _vars_before_p4est VARIABLES )
-    list( APPEND CMAKE_MESSAGE_CONTEXT "p4est" )
-    add_subdirectory( ${CMAKE_CURRENT_LIST_DIR}/p4est )
-    list( POP_BACK CMAKE_MESSAGE_CONTEXT )
-    # Capture the list of variables after adding the subdirectory
-    get_cmake_property( _vars_after_p4est VARIABLES )
-    # Compute the difference (new variables added by the subdirectory)
-    set( _new_p4est_vars )
-    foreach( _var IN LISTS _vars_after_p4est )
-        if( NOT _var IN_LIST _vars_before_p4est )
-            list( APPEND _new_p4est_vars ${_var} )
-        endif()
-    endforeach()
-
-    # Mark the new variables as advanced
-    mark_as_advanced( FORCE ${_new_p4est_vars} )
 endif()
 
-# Workaround: Suppress warnings for googletests, so it does not compromise the usage of -WError for t8code.
-# -----------
-# 1. Save original flags
-set(ORIGINAL_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
-set(ORIGINAL_C_FLAGS   "${CMAKE_C_FLAGS}")
-
-# 2. Suppress warnings for GoogleTest build
-set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -w" CACHE STRING "" FORCE)
-set(CMAKE_C_FLAGS   "${CMAKE_C_FLAGS}   -w" CACHE STRING "" FORCE)
-
-FetchContent_MakeAvailable( googletest )
-
-# 3. Restore original flags
-set(CMAKE_CXX_FLAGS "${ORIGINAL_CXX_FLAGS}" CACHE STRING "" FORCE)
-set(CMAKE_C_FLAGS   "${ORIGINAL_C_FLAGS}"   CACHE STRING "" FORCE)
-
-# End of workaround
-
-# Mark all cmake options starting with FETCHCONTENT as advanced.
-get_cmake_property(_cmake_vars VARIABLES)
-foreach(_var ${_cmake_vars})
-    if(_var MATCHES "^FETCHCONTENT_.*")
-	    mark_as_advanced(${_var})
-    endif()
-endforeach()
-
 add_subdirectory( ${CMAKE_CURRENT_LIST_DIR}/src )
 
 if( T8CODE_BUILD_MESH_HANDLE )