RFR [XS]: 8236709: struct SwitchRange in HS violates C++ One Definition Rule - was RE: struct SwitchRange and C++ One Definition Rule [-Wodr]

[Baesken, Matthias]

Hello, please review  this small fix for an issue  that I was running into  when experimenting  with  gcc8  and   the -flto compiler flag .
When building with those flags,  the gcc8 warns that  the  SwitchRange   classes  in HS code   violate the C++ One Definition Rule .
So I renamed one of those 2  SwitchRange   classes .

 Bug/webrev :

https://bugs.openjdk.java.net/browse/JDK-8236709

http://cr.openjdk.java.net/~mbaesken/webrevs/8236709.0/


Thanks, Matthias


> > Hello,  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_LIRGener
> > ator.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
> >
> >
> > Do  you think this should be fixed ( renaming  one SwitchRange  ) ?
> >
> >
> > Martin suggested that  even without  flto added   it could be problematic .
>
> Yes, please file a bug and let's get this fixed quickly.  This sort of thing can
> lead
> to really weird looking problems, like using the same vtable (which one
> picked
> “at random”) for instances of both classes.