Add sending to subscript getter sending result

Author: stzn

lib/AST/ASTPrinter.cpp

@@ -4450,6 +4450,13 @@ void PrintAST::visitSubscriptDecl(SubscriptDecl *decl) {
     Printer.printDeclResultTypePre(decl, elementTy);
     Printer.callPrintStructurePre(PrintStructureKind::FunctionReturnType);
 
+    if (!Options.SuppressSendingArgsAndResults) {
+      if (auto typeRepr = decl->getElementTypeRepr()) {
+        if (isa<SendingTypeRepr>(decl->getResultTypeRepr()))
+          Printer << "sending ";
+      }
+    }
+
     PrintWithOpaqueResultTypeKeywordRAII x(Options);
     printTypeLocForImplicitlyUnwrappedOptional(
       elementTy, decl->isImplicitlyUnwrappedOptional());

lib/AST/Decl.cpp

@@ -10754,6 +10754,9 @@ AccessorDecl *AccessorDecl::createParsed(
 
       newParams.push_back(param);
     }
+
+    if (isa<SendingTypeRepr>(SD->getElementTypeRepr()))
+      accessor->setSendingResult();
   }
   accessor->setParameters(
       ParameterList::create(ctx, paramsStart, newParams, paramsEnd));

lib/Sema/TypeCheckDecl.cpp

@@ -2638,6 +2638,10 @@ InterfaceTypeRequest::evaluate(Evaluator &eval, ValueDecl *D) const {
     AnyFunctionType::ExtInfoBuilder infoBuilder;
     maybeAddParameterIsolation(infoBuilder, argTy);
 
+    if (auto typeRepr = SD->getElementTypeRepr())
+      if (isa<SendingTypeRepr>(typeRepr))
+        infoBuilder = infoBuilder.withSendingResult();
+
     Type funcTy;
     // FIXME: Verify ExtInfo state is correct, not working by accident.
     auto info = infoBuilder.build();

test/Concurrency/sending_subscript.swift

@@ -0,0 +1,13 @@
+// RUN: %target-swift-frontend -swift-version 6 %s -emit-silgen | %FileCheck %s
+
+// REQUIRES: concurrency
+
+class NonSendableKlass {}
+
+// CHECK: subscript(_: sending NonSendableKlass) -> sending NonSendableKlass { get }
+
+// CHECK: sil hidden [ossa] @$s17sending_subscript1SVyAA16NonSendableKlassCAEncig : $@convention(method) (@sil_sending @owned NonSendableKlass, S) -> @sil_sending @owned NonSendableKlass {
+struct S {
+  subscript(_: sending NonSendableKlass) -> sending NonSendableKlass { NonSendableKlass() }
+}
+