Drop the ModuleDecl parameter from SILFunctionType::getWitnessMethodClass().

Nothing uses this parameter.

Author: DougGregor

include/swift/AST/Types.h

@@ -4010,7 +4010,7 @@ class SILFunctionType final : public TypeBase, public llvm::FoldingSetNode,
   /// If this is a @convention(witness_method) function with a class
   /// constrained self parameter, return the class constraint for the
   /// Self type.
-  ClassDecl *getWitnessMethodClass(ModuleDecl &M) const;
+  ClassDecl *getWitnessMethodClass() const;
 
   /// If this is a @convention(witness_method) function, return the conformance
   /// for which the method is a witness.

lib/SIL/SILFunctionType.cpp

@@ -99,7 +99,7 @@ CanType SILFunctionType::getSelfInstanceType() const {
 }
 
 ClassDecl *
-SILFunctionType::getWitnessMethodClass(ModuleDecl &M) const {
+SILFunctionType::getWitnessMethodClass() const {
   auto selfTy = getSelfInstanceType();
   auto genericSig = getGenericSignature();
   if (auto paramTy = dyn_cast<GenericTypeParamType>(selfTy)) {

lib/SILOptimizer/Utils/Devirtualize.cpp

@@ -950,7 +950,7 @@ swift::getWitnessMethodSubstitutions(SILModule &Module, ApplySite AI,
   auto *mod = Module.getSwiftModule();
   bool isSelfAbstract =
     witnessFnTy->getSelfInstanceType()->is<GenericTypeParamType>();
-  auto *classWitness = witnessFnTy->getWitnessMethodClass(*mod);
+  auto *classWitness = witnessFnTy->getWitnessMethodClass();
 
   return ::getWitnessMethodSubstitutions(mod, CRef, requirementSig,
                                          witnessThunkSig, origSubs,