Remove unused PolymorphicFunctionType::substGenericArgs.

NFC.

Author: jckarter

include/swift/AST/Types.h

@@ -2350,16 +2350,6 @@ class PolymorphicFunctionType : public AnyFunctionType {
 
   GenericParamList &getGenericParams() const { return *Params; }
 
-  /// Substitute the given generic arguments into this polymorphic
-  /// function type and return the resulting non-polymorphic type.
-  FunctionType *substGenericArgs(ModuleDecl *M, ArrayRef<Type> args);
-
-  /// Substitute the given generic arguments into this polymorphic
-  /// function type and return the resulting non-polymorphic type.
-  ///
-  /// The order of Substitutions must match the order of generic archetypes.
-  FunctionType *substGenericArgs(ModuleDecl *M, ArrayRef<Substitution> subs);
-
   // Implement isa/cast/dyncast/etc.
   static bool classof(const TypeBase *T) {
     return T->getKind() == TypeKind::PolymorphicFunction;

lib/AST/Type.cpp

@@ -2109,22 +2109,6 @@ PolymorphicFunctionType::getGenericParameters() const {
   return Params->getParams();
 }
 
-FunctionType *PolymorphicFunctionType::substGenericArgs(Module *module,
-                                                        ArrayRef<Type> args) {
-  TypeSubstitutionMap map;
-  for (auto &param : getGenericParams().getNestedGenericParams()) {
-    map.insert(std::make_pair(param->getArchetype(), args.front()));
-    args = args.slice(1);
-  }
-  
-  assert(args.empty()
-         && "number of args did not match number of generic params");
-  
-  Type input = getInput().subst(module, map, SubstFlags::IgnoreMissing);
-  Type result = getResult().subst(module, map, SubstFlags::IgnoreMissing);
-  return FunctionType::get(input, result, getExtInfo());
-}
-
 TypeSubstitutionMap
 GenericParamList::getSubstitutionMap(ArrayRef<swift::Substitution> Subs) const {
   TypeSubstitutionMap map;
@@ -2140,16 +2124,6 @@ GenericParamList::getSubstitutionMap(ArrayRef<swift::Substitution> Subs) const {
   return map;
 }
 
-FunctionType *PolymorphicFunctionType::substGenericArgs(Module *module,
-                                                  ArrayRef<Substitution> subs) {
-  TypeSubstitutionMap map
-    = getGenericParams().getSubstitutionMap(subs);
-  
-  Type input = getInput().subst(module, map, SubstFlags::IgnoreMissing);
-  Type result = getResult().subst(module, map, SubstFlags::IgnoreMissing);
-  return FunctionType::get(input, result, getExtInfo());
-}
-
 FunctionType *
 GenericFunctionType::substGenericArgs(Module *M, ArrayRef<Type> args) const {
   auto params = getGenericParams();