In Epsilon GC, we have the call like:

EpsilonBarrierSet::EpsilonBarrierSet() : BarrierSet(
          make_barrier_set_assembler<BarrierSetAssembler>(),
          make_barrier_set_c1<BarrierSetC1>(),
          make_barrier_set_c2<BarrierSetC2>(),
          BarrierSet::FakeRtti(BarrierSet::EpsilonBarrierSet)) {};

...and some compilers (notably Mac OS builds) complain that:

/Users/yosemite/jdk-sandbox/src/hotspot/share/gc/epsilon/epsilonBarrierSet.cpp:40:11: error: base class 'BarrierSet' is uninitialized when used here to access 'BarrierSet::make_barrier_set_assembler<BarrierSetAssembler>' [-Werror,-Wuninitialized]
          make_barrier_set_assembler<BarrierSetAssembler>(),
          ^
/Users/yosemite/jdk-sandbox/src/hotspot/share/gc/epsilon/epsilonBarrierSet.cpp:41:11: error: base class 'BarrierSet' is uninitialized when used here to access 'BarrierSet::make_barrier_set_c1<BarrierSetC1>' [-Werror,-Wuninitialized]
          make_barrier_set_c1<BarrierSetC1>(),
          ^
/Users/yosemite/jdk-sandbox/src/hotspot/share/gc/epsilon/epsilonBarrierSet.cpp:42:11: error: base class 'BarrierSet' is uninitialized when used here to access 'BarrierSet::make_barrier_set_c2<BarrierSetC2>' [-Werror,-Wuninitialized]
          make_barrier_set_c2<BarrierSetC2>(),

This warning is legit: we are calling instance method of BarrierSet before initializing it. But, those methods are just factory methods, and they could be static, resolving the warning.