In file included from hb-ot-face.cc:41:
./hb-ot-layout-gsub-table.hh:293:7: error: template parameter redefines default argument
         hb_requires (hb_is_sorted_source_of (Iterator,
         ^
./hb-meta.hh:59:27: note: expanded from macro 'hb_requires'
 define hb_requires(Cond) hb_enable_if((Cond))
                          ^
./hb-meta.hh:57:67: note: expanded from macro 'hb_enable_if'
 define hb_enable_if(Cond) typename hb_enable_if<(Cond)>::type* = nullptr
                                                                  ^
./hb-ot-layout-gsub-table.hh:40:5: note: previous default template argument defined here
    hb_requires (hb_is_sorted_source_of (Iterator,
    ^
./hb-meta.hh:59:27: note: expanded from macro 'hb_requires'
 define hb_requires(Cond) hb_enable_if((Cond))
                          ^
./hb-meta.hh:57:67: note: expanded from macro 'hb_enable_if'
 define hb_enable_if(Cond) typename hb_enable_if<(Cond)>::type* = nullptr
                                                                  ^
1 error generated.