add additional function argument where we can supply our own CMakeLists.txt file

cmake/Modules/ExternalCMakeProject.cmake

@@ -2,7 +2,7 @@
 # The sources will be unpacked to ${CMAKE_BINARY_DIR}/_deps/${target}-src
 # The binaries will be built in ${CMAKE_BINARY_DIR}/_deps/${target}-build
 #
-function(ExternalCMakeProject target url hash basedir cmakedir)
+function(ExternalCMakeProject target url hash basedir cmakedir cmakefile)
   # change settings locally
   set(BUILD_SHARED_LIBS OFF)
   set(CMAKE_POSITION_INDEPENDENT_CODE ON)
@@ -23,6 +23,9 @@ function(ExternalCMakeProject target url hash basedir cmakedir)
     endif()
     file(REMOVE_RECURSE ${CMAKE_BINARY_DIR}/_deps/${target}-src)
     file(RENAME ${TARGET_SOURCE} ${CMAKE_BINARY_DIR}/_deps/${target}-src)
+    if(NOT (cmakefile STREQUAL ""))
+      file(COPY ${cmakefile} ${CMAKE_BINARY_DIR}/_deps/${target}-src/${cmakedir}/CMakeLists.txt)
+    endif()
     add_subdirectory("${CMAKE_BINARY_DIR}/_deps/${target}-src/${cmakedir}"
       "${CMAKE_BINARY_DIR}/_deps/${target}-build")
   else()
@@ -30,6 +33,14 @@ function(ExternalCMakeProject target url hash basedir cmakedir)
     message(STATUS "Downloading ${url}")
     FetchContent_Declare(${target} URL ${url} URL_HASH MD5=${hash} SOURCE_SUBDIR ${cmakedir})
     message(STATUS "Unpacking and configuring ${archive}")
-    FetchContent_MakeAvailable(${target})
+    FetchContent_GetProperties(${target})
+    FetchContent_Populate(${target})
+    if(NOT (cmakefile STREQUAL ""))
+      file(COPY "${cmakefile}" DESTINATION "${${target}_SOURCE_DIR}/${cmakedir}/")
+      get_filename_component(_cmakefile "${cmakefile}" NAME)
+      file(RENAME "${${target}_SOURCE_DIR}/${cmakedir}/${_cmakefile}"
+        "${${target}_SOURCE_DIR}/${cmakedir}/CMakeLists.txt")
+    endif()
+    add_subdirectory("${${target}_SOURCE_DIR}/${cmakedir}" "${${target}_BINARY_DIR}")
   endif()
 endfunction(ExternalCMakeProject)

cmake/Modules/Packages/MSCG.cmake

@@ -13,7 +13,7 @@ if(DOWNLOAD_MSCG)
   mark_as_advanced(MSCG_MD5)
 
   include(ExternalCMakeProject)
-  ExternalCMakeProject(mscg ${MSCG_URL} ${MSCG_MD5} MSCG-release src/CMake)
+  ExternalCMakeProject(mscg ${MSCG_URL} ${MSCG_MD5} MSCG-release src/CMake "")
 
   # set include and link library
   target_include_directories(lammps PRIVATE "${CMAKE_BINARY_DIR}/_deps/mscg-src/src")

unittest/CMakeLists.txt

@@ -12,7 +12,7 @@ mark_as_advanced(GTEST_MD5)
 set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
 
 include(ExternalCMakeProject)
-ExternalCMakeProject(googletest ${GTEST_URL} ${GTEST_MD5} googletest .)
+ExternalCMakeProject(googletest ${GTEST_URL} ${GTEST_MD5} googletest . "")
 add_library(GTest::GTest ALIAS gtest)
 add_library(GTest::GMock ALIAS gmock)
 add_library(GTest::GTestMain ALIAS gtest_main)

unittest/force-styles/CMakeLists.libyaml

@@ -0,0 +1,33 @@
+# Custom CMake file for libyaml
+
+cmake_minimum_required(VERSION 3.10)
+project(libyaml VERSION 0.2.5
+  DESCRIPTION "LibYAML a YAML parser and emitter library"
+  LANGUAGES C
+  HOMEPAGE_URL https://pyyaml.org/wiki/LibYAML)
+
+# compilation settings and options
+option(BUILD_SHARED_LIBS "Build libYAML as a shared library" OFF)
+option(CMAKE_POSITION_INDEPENDENT_CODE "Create objects compatible with shared libraries" ON)
+
+include(GNUInstallDirs)
+
+add_library(yaml
+  src/api.c
+  src/dumper.c
+  src/emitter.c
+  src/loader.c
+  src/parser.c
+  src/reader.c
+  src/scanner.c
+  src/writer.c
+  )
+
+set (YAML_VERSION_MAJOR ${libyaml_VERSION_MAJOR})
+set (YAML_VERSION_MINOR ${libyaml_VERSION_MINOR})
+set (YAML_VERSION_PATCH ${libyaml_VERSION_PATCH})
+set (YAML_VERSION_STRING "${YAML_VERSION_MAJOR}.${YAML_VERSION_MINOR}.${YAML_VERSION_PATCH}")
+
+configure_file(cmake/config.h.in config.h)
+target_compile_definitions(yaml PRIVATE YAML_DECLARE_STATIC HAVE_CONFIG_H)
+target_include_directories(yaml PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/include ${CMAKE_CURRENT_BINARY_DIR})

unittest/force-styles/CMakeLists.txt

@@ -1,14 +1,14 @@
 
 find_package(YAML)
 if(NOT YAML_FOUND)
-  set(YAML_URL "https://github.com/akohlmey/libyaml/archive/refs/heads/new-cmake.tar.gz" CACHE STRING "URL for libyaml tarball")
+  set(YAML_URL "https://pyyaml.org/download/libyaml/yaml-0.2.5.tar.gz" CACHE STRING "URL for libyaml tarball")
-  set(YAML_MD5 "1683f5957a79d7a823e09575b0488df2" CACHE STRING "MD5 checksum of libyaml tarball")
+  set(YAML_MD5 "bb15429d8fb787e7d3f1c83ae129a999" CACHE STRING "MD5 checksum of libyaml tarball")
   mark_as_advanced(YAML_URL)
   mark_as_advanced(YAML_MD5)
 
   # download and build a local copy of libyaml
   include(ExternalCMakeProject)
-  ExternalCMakeProject(libyaml ${YAML_URL} ${YAML_MD5} libyaml .)
+  ExternalCMakeProject(libyaml ${YAML_URL} ${YAML_MD5} libyaml . CMakeLists.libyaml)
   add_library(Yaml::Yaml ALIAS yaml)
 endif()