cmake don't automatically enable ccache if already enabled

CMakeLists.txt

@@ -231,7 +231,18 @@ endforeach()
 option(CCACHE "Use ccache if available" ON)
 find_program(CCACHE_PROGRAM ccache)
 if (CCACHE AND CCACHE_PROGRAM AND NOT DEFINED ENV{CCACHE_DISABLE})
-	set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CCACHE_PROGRAM}")
+
+	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} -> ${cxx_real_path})")
+	else()
+		message(STATUS "ccache enabled (export CCACHE_DISABLE=1 to disable)")
+		set_property(GLOBAL PROPERTY RULE_LAUNCH_COMPILE "${CCACHE_PROGRAM}")
+	endif()
+
 endif()
 
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