when experimenting with gcc8 and the -flto compiler flag I was running into these warnings in the c1 coding :
  
  
 /open_jdk/jdk_3/jdk/src/hotspot/share/c1/c1_LIRGenerator.hpp:50:7: warning: type 'struct SwitchRange' violates the C++ One Definition Rule [-Wodr]
 class SwitchRange: public CompilationResourceObj {
        ^
 /open_jdk/jdk_3/jdk/src/hotspot/share/opto/parse2.cpp:319: note: a different type is defined in another translation unit
 class SwitchRange : public StackObj {
   /usr/work/d040975/open_jdk/jdk_3/jdk/src/hotspot/share/c1/c1_LIRGenerator.hpp:52:7: note: the first difference of corresponding definitions is field '_low_key'
    int _low_key;
        ^
 /open_jdk/jdk_3/jdk/src/hotspot/share/opto/parse2.cpp:321: note: a field with different name is defined in another translation unit
    jint _lo; // inclusive lower limit