px4-firmware/cmake/ccache.cmake

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# ccache

option(CCACHE "Use ccache if available" ON)
find_program(CCACHE_PROGRAM ccache)
if(CCACHE AND CCACHE_PROGRAM AND NOT DEFINED ENV{CCACHE_DISABLE})
	get_filename_component(ccache_real_path ${CCACHE_PROGRAM} REALPATH)
	get_filename_component(cxx_real_path ${CMAKE_CXX_COMPILER} REALPATH)
	get_filename_component(cxx_abs_path ${CMAKE_CXX_COMPILER} ABSOLUTE)

	if ("${ccache_real_path}" STREQUAL "${cxx_real_path}")
		message(STATUS "ccache enabled via symlink (${cxx_abs_path} -> ${cxx_real_path})")
		set(CCACHE_PROGRAM "" CACHE INTERNAL "ccache program" FORCE)
	else()
		message(STATUS "ccache enabled (export CCACHE_DISABLE=1 to disable)")
		set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CCACHE_PROGRAM}")
	endif()
else()
	set(CCACHE_PROGRAM "" CACHE INTERNAL "ccache program" FORCE)
endif()