···1+diff --git a/CMakeLists.txt b/CMakeLists.txt
2+--- a/CMakeLists.txt
3++++ b/CMakeLists.txt
4+@@ -37,21 +37,6 @@ message(STATUS "default momentum and length are ${HEPMC_DEFAULT_MOM_UNIT} ${HEPM
5+ # find the HepMC cmake modules
6+ set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_SOURCE_DIR}/cmake/Modules ${CMAKE_MODULE_PATH})
7+8+-# make sure we are not building from within the source code directory
9+-string(COMPARE EQUAL "${CMAKE_SOURCE_DIR}" "${CMAKE_BINARY_DIR}" in_source)
10+-string( REGEX MATCH "${CMAKE_SOURCE_DIR}/" in_source_subdir
11+-"${CMAKE_BINARY_DIR}")
12+-if (in_source OR in_source_subdir)
13+- message(FATAL_ERROR "
14+-ERROR: In source builds of this project are not allowed.
15+-A separate build directory is required.
16+-Please create one and run cmake from the build directory.
17+-Also note that cmake has just added files to your source code directory.
18+-We suggest getting a new copy of the source code.
19+-Otherwise, delete `CMakeCache.txt' and the directory `CMakeFiles'.
20+- ")
21+-endif ()
22+-
23+ # build_docs is OFF (false) by default
24+ if ( build_docs )
25+ message(STATUS "documents WILL be built and installed" )