Merge pull request #2476 from akohlmey/download-libyaml

Add CMake code to download and compile a suitable version of libyaml in case it is not found locally

cmake/Modules/YAML.cmake

@@ -0,0 +1,32 @@
+message(STATUS "Downloading and building YAML library")
+
+include(ExternalProject)
+set(YAML_URL "https://pyyaml.org/download/libyaml/yaml-0.2.5.tar.gz" CACHE STRING "URL for libyaml tarball")
+mark_as_advanced(YAML_URL)
+ExternalProject_Add(libyaml
+                    URL               ${YAML_URL}
+                    URL_MD5           bb15429d8fb787e7d3f1c83ae129a999
+                    SOURCE_DIR        "${CMAKE_BINARY_DIR}/yaml-src"
+                    BINARY_DIR        "${CMAKE_BINARY_DIR}/yaml-build"
+                    CONFIGURE_COMMAND <SOURCE_DIR>/configure ${CONFIGURE_REQUEST_PIC}
+                                      CXX=${CMAKE_CXX_COMPILER}
+                                      CC=${CMAKE_C_COMPILER}
+                                      --prefix=<INSTALL_DIR> --disable-shared
+                    BUILD_BYPRODUCTS  <INSTALL_DIR>/lib/${CMAKE_FIND_LIBRARY_PREFIXES}yaml.a
+                    TEST_COMMAND      "")
+
+ExternalProject_Get_Property(libyaml INSTALL_DIR)
+set(YAML_INCLUDE_DIR ${INSTALL_DIR}/include)
+set(YAML_LIBRARY_DIR ${INSTALL_DIR}/lib)
+
+# workaround for CMake 3.10 on ubuntu 18.04
+file(MAKE_DIRECTORY ${YAML_INCLUDE_DIR})
+file(MAKE_DIRECTORY ${YAML_LIBRARY_DIR})
+
+set(YAML_LIBRARY_PATH ${INSTALL_DIR}/lib/${CMAKE_FIND_LIBRARY_PREFIXES}yaml.a)
+
+add_library(Yaml::Yaml UNKNOWN IMPORTED)
+set_target_properties(Yaml::Yaml PROPERTIES
+        IMPORTED_LOCATION ${YAML_LIBRARY_PATH}
+        INTERFACE_INCLUDE_DIRECTORIES ${YAML_INCLUDE_DIR})
+add_dependencies(Yaml::Yaml libyaml)

doc/src/Build_development.rst

@@ -111,8 +111,10 @@ error margin).  The status of this automated testing can be viewed on
 The unit testing facility is integrated into the CMake build process
 of the LAMMPS source code distribution itself.  It can be enabled by
 setting ``-D ENABLE_TESTING=on`` during the CMake configuration step.
-It requires the `PyYAML <http://pyyaml.org/>`_ library and development
-headers to compile and will download and compile a recent version of the
+It requires the `YAML <http://pyyaml.org/>`_ library and development
+headers (if not found locally a recent version will be downloaded
+and compiled transparently) to compile and will download and compile
+a specific recent version of the
 `Googletest <https://github.com/google/googletest/>`_ C++ test framework
 for implementing the tests.
 

unittest/force-styles/CMakeLists.txt

@@ -1,8 +1,8 @@
 
 find_package(YAML)
 if(NOT YAML_FOUND)
-  message(STATUS "Skipping tests because libyaml is not found")
-  return()
+  # download and build a local copy of libyaml
+  include(YAML)
 endif()
 
 if(CMAKE_VERSION VERSION_LESS 3.12)