From 7ec9a535b2c8b24c38abd331fcecc5fb5068ec7d Mon Sep 17 00:00:00 2001
From: Luc Grosheintz <luc.grosheintz@gmail.com>
Date: Tue, 5 Nov 2024 16:19:06 +0100
Subject: [PATCH] Guard targets in `HighFiveConfig.cmake`. (#1053)

---
 cmake/HighFiveConfig.cmake                    | 16 ++++---
 .../test_cmake_integration.sh                 | 43 ++++++++++++-------
 .../test_dependent_library/CMakeLists.txt     | 23 ++++++++++
 3 files changed, 60 insertions(+), 22 deletions(-)

diff --git a/cmake/HighFiveConfig.cmake b/cmake/HighFiveConfig.cmake
index 33ce7b7b0..a263264cf 100644
--- a/cmake/HighFiveConfig.cmake
+++ b/cmake/HighFiveConfig.cmake
@@ -8,12 +8,16 @@ if(HIGHFIVE_FIND_HDF5)
   find_dependency(HDF5)
 endif()
 
-include("${CMAKE_CURRENT_LIST_DIR}/HighFiveTargets.cmake")
+if(NOT TARGET HighFive)
+  include("${CMAKE_CURRENT_LIST_DIR}/HighFiveTargets.cmake")
 
-if(HDF5_IS_PARALLEL)
-  find_dependency(MPI)
-  target_link_libraries(HighFive::HighFive INTERFACE MPI::MPI_C MPI::MPI_CXX)
+  if(HDF5_IS_PARALLEL)
+    find_dependency(MPI)
+    target_link_libraries(HighFive::HighFive INTERFACE MPI::MPI_C MPI::MPI_CXX)
+  endif()
+
+  add_library(HighFive ALIAS HighFive::HighFive)
+  add_library(HighFiveInclude ALIAS HighFive::Include)
 endif()
 
-add_library(HighFive ALIAS HighFive::HighFive)
-add_library(HighFiveInclude ALIAS HighFive::Include)
+
diff --git a/tests/cmake_integration/test_cmake_integration.sh b/tests/cmake_integration/test_cmake_integration.sh
index cf80fbfdd..74fd743c1 100644
--- a/tests/cmake_integration/test_cmake_integration.sh
+++ b/tests/cmake_integration/test_cmake_integration.sh
@@ -16,6 +16,15 @@ HIGHFIVE_INSTALL_DIR="${HIGHFIVE_BUILD_DIR}/install"
 export HIGHFIVE_GIT_REPOSITORY="file://$(realpath "$HIGHFIVE_DIR")"
 export HIGHFIVE_GIT_TAG=$(git rev-parse HEAD)
 
+make_submodule() {
+    local project_dir="$1"
+    local dep_dir="${project_dir}/deps/HighFive"
+
+    rm "${dep_dir}" || true
+    mkdir -p "$(dirname "${dep_dir}")"
+    ln -sf "${HIGHFIVE_DIR}" "${dep_dir}"
+}
+
 test_dependent_library() {
     local project="dependent_library"
     local project_dir="${TEST_DIR}/${project}"
@@ -35,33 +44,35 @@ test_dependent_library() {
 
       cmake --build "${build_dir}" --verbose --target install
 
-      local test_project="test_dependent_library"
-      local test_build_dir="${TMP_DIR}/test_build"
-      local test_install_dir="${TMP_DIR}/test_build/install"
 
-      rm -rf ${test_build_dir} || true
+      for vendor in submodule fetch_content external none
+      do
+        local test_project="test_dependent_library"
+        local test_build_dir="${TMP_DIR}/test_build"
+        local test_install_dir="${TMP_DIR}/test_build/install"
+
+        make_submodule ${test_project}
 
-      cmake -DUSE_BOOST=${use_boost} \
-            -DCMAKE_PREFIX_PATH="${HIGHFIVE_INSTALL_DIR};${install_dir}" \
-            -DCMAKE_INSTALL_PREFIX="${test_install_dir}" \
-            -B "${test_build_dir}" "${test_project}"
 
-      cmake --build "${test_build_dir}" --verbose
-      ctest --test-dir "${test_build_dir}" --verbose
+        rm -rf ${test_build_dir} || true
 
+        cmake -DUSE_BOOST=${use_boost} \
+              -DVENDOR_STRATEGY=${vendor} \
+              -DCMAKE_PREFIX_PATH="${HIGHFIVE_INSTALL_DIR};${install_dir}" \
+              -DCMAKE_INSTALL_PREFIX="${test_install_dir}" \
+              -B "${test_build_dir}" "${test_project}"
+
+        cmake --build "${test_build_dir}" --verbose
+        ctest --test-dir "${test_build_dir}" --verbose
+      done
     done
 }
 
 test_application() {
     local project="application"
     local project_dir="${TEST_DIR}/${project}"
-    local dep_dir="${TEST_DIR}/${project}/deps/HighFive"
-
-    rm "${dep_dir}" || true
-    ln -sf "${HIGHFIVE_DIR}" "${dep_dir}"
 
-    echo ${HIGHFIVE_DIR}
-    echo ${dep_dir}
+    make_submodule ${project_dir}
 
     for vendor in submodule fetch_content external
     do
diff --git a/tests/cmake_integration/test_dependent_library/CMakeLists.txt b/tests/cmake_integration/test_dependent_library/CMakeLists.txt
index c9023f98a..15851c3c6 100644
--- a/tests/cmake_integration/test_dependent_library/CMakeLists.txt
+++ b/tests/cmake_integration/test_dependent_library/CMakeLists.txt
@@ -7,8 +7,31 @@ if(NOT DEFINED CMAKE_CXX_STANDARD)
   set(CMAKE_CXX_EXTENSIONS OFF)
 endif()
 
+set(VENDOR_STRATEGY "submodule" CACHE STRING "Use 'submodule' for Git submodules, 'fetch_content' for FetchContent, 'external' for `find_package`, 'none' for making to attempt at finding HighFive.")
+
 add_executable(test_hi5_dependent test_dependent_library.cpp)
 
+if(${VENDOR_STRATEGY} STREQUAL "submodule")
+  # When vendoring via a Git submodule, this is the correct
+  # line to include HighFive.
+  add_subdirectory("deps/HighFive" EXCLUDE_FROM_ALL)
+elseif(${VENDOR_STRATEGY} STREQUAL "fetch_content")
+  include(FetchContent)
+  FetchContent_Declare(HighFive
+    GIT_REPOSITORY $ENV{HIGHFIVE_GIT_REPOSITORY}
+    GIT_TAG $ENV{HIGHFIVE_GIT_TAG}
+  )
+  FetchContent_MakeAvailable(HighFive)
+elseif(${VENDOR_STRATEGY} STREQUAL "external")
+  # When HighFive is installed like regular software and then "found", do the
+  # following:
+  find_package(HighFive REQUIRED)
+endif()
+
+if(NOT ${VENDOR_STRATEGY} STREQUAL "none")
+  target_link_libraries(test_hi5_dependent PUBLIC HighFive::HighFive)
+endif()
+
 if(NOT USE_BOOST)
   find_package(Hi5Dependent REQUIRED)
   target_link_libraries(test_hi5_dependent PUBLIC Hi5Dependent::Read Hi5Dependent::Write)