gzdoom-gles/cmake/precompiled_headers.cmake
alexey.lysiuk 220d923e65 Do not write g_pch.cpp if it's already up-to-date
This eliminates rebuilding of main executable by MSVC on every project generation by CMake
2018-04-19 11:36:52 +03:00

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CMake

#
# Christoph Heindl 2010
# Precompiled Headers Demo
# http://cheind.wordpress.com
#
# Instructs the MSVC toolset to use the precompiled header PRECOMPILED_HEADER
# for each source file given in the collection named by SOURCE_VARIABLE_NAME.
function(enable_precompiled_headers PRECOMPILED_HEADER SOURCE_VARIABLE_NAME)
if(MSVC)
set(files ${${SOURCE_VARIABLE_NAME}})
# Generate precompiled header translation unit
get_filename_component(pch_basename ${PRECOMPILED_HEADER} NAME_WE)
set(pch_abs ${CMAKE_CURRENT_SOURCE_DIR}/${PRECOMPILED_HEADER})
set(pch_unity ${CMAKE_CURRENT_BINARY_DIR}/${pch_basename}.cpp)
set(pch_content "// Precompiled header unity generated by CMake\n#include <${pch_abs}>\n")
# Read .cpp if exists
if(EXISTS ${pch_unity})
file(READ ${pch_unity} pch_content_prev)
endif()
# Compare existing .cpp content with the actual one
if (pch_content_prev AND pch_content STREQUAL pch_content_prev)
unset(pch_content)
endif()
# Write .cpp if it's out-of-date
if (pch_content)
FILE(WRITE ${pch_unity} "${pch_content}")
endif()
set_source_files_properties(${pch_unity} PROPERTIES COMPILE_FLAGS "/Yc\"${pch_abs}\"")
# Update properties of source files to use the precompiled header.
# Additionally, force the inclusion of the precompiled header at beginning of each source file.
foreach(source_file ${files} )
set_source_files_properties(
${source_file}
PROPERTIES COMPILE_FLAGS
"/Yu\"${pch_abs}\" /FI\"${pch_abs}\""
)
endforeach(source_file)
# Finally, update the source file collection to contain the precompiled header translation unit
set(${SOURCE_VARIABLE_NAME} ${${SOURCE_VARIABLE_NAME}} ${pch_unity} PARENT_SCOPE)
endif(MSVC)
endfunction(enable_precompiled_headers)