+ darwin | darwin[1-7] | darwin[1-7].*)
+ # On Darwin, performance is improved if libstdc++ is single-module.
+ # Up to at least 10.3.7, -flat_namespace is required for proper
+ # treatment of coalesced symbols.
+ OPT_LDFLAGS="${OPT_LDFLAGS} -Wl,-single_module -Wl,-flat_namespace"
+ os_include_dir="os/bsd/darwin"
+ ;;
+ darwin[89] | darwin[89].* | darwin[1-9][0-9]* )
+ # On Darwin, performance is improved if libstdc++ is single-module,
+ # and on 8+ compatibility is better if not -flat_namespace.
+ OPT_LDFLAGS="${OPT_LDFLAGS} -Wl,-single_module"
+ os_include_dir="os/bsd/darwin"
+ ;;