IRGen: Fix crash when emitting metadata for enum with @autoclosure case

Fixes <rdar://problem/45962425>, <https://bugs.swift.org/browse/SR-9169>.

Author: slavapestov

lib/AST/Decl.cpp

@@ -5890,9 +5890,14 @@ Type EnumElementDecl::getArgumentInterfaceType() const {
 
   auto funcTy = interfaceType->castTo<AnyFunctionType>();
   funcTy = funcTy->getResult()->castTo<FunctionType>();
-  return AnyFunctionType::composeInput(funcTy->getASTContext(),
-                                       funcTy->getParams(),
-                                       /*canonicalVararg=*/false);
+
+  auto &ctx = getASTContext();
+  SmallVector<TupleTypeElt, 4> elements;
+  for (const auto &param : funcTy->getParams()) {
+    Type eltType = param.getParameterType(/*canonicalVararg=*/false, &ctx);
+    elements.emplace_back(eltType, param.getLabel());
+  }
+  return TupleType::get(elements, ctx);
 }
 
 EnumCaseDecl *EnumElementDecl::getParentCase() const {

test/IRGen/enum_function_payload.swift

@@ -14,3 +14,11 @@ enum Multi {
   case F((Multi) -> ())
   case G((Multi) -> ())
 }
+
+enum Autoclosure<T> {
+  case first(@autoclosure () -> Bool, T)
+  case second(Int, @autoclosure () -> T)
+}
+
+_ = Autoclosure.first(false, 3)
+_ = Autoclosure.second(3, "hi")