More re Bug 331877 -  [compiler][generics] implicit inheritance must apply substitution for type variables from outer scope
Motivated by OTREInternalError "base-call impossible" due to discrepancy between compiler & OTRE:
Improve the strategy for parameterized role methods from r1170:
- NPE-fix in setCopyInheritanceSrc()
- re-usable helper method MethodBinding.getCodeGenType(int)
  - this helper also reverts substitution of mapping-level type variables
- apply the same strategy (from MethodBinding.signature()) consistently to all
  uses of MethodSpec, too, including especially CallinMethodMappingsAttribute.
Revert structure from r1143, which is superseded by the above strategy change:
- we no longer need to know where a mapping is inherited from, since we 
  will find the correct method using signature comparison
9 files changed