[concurrency] Make captured self in a closure show up as an @sil_isolated parameter in the closure's function signature.

This ensures that when region isolation is enabled, we can begin properly
modeling when a closure should not be allowed to be isolated. In the next
commit, I am going to loosen this and we should be able to pass in actors
outside of methods without the closure being afflicted with "actor
derived-ness".

lib/SIL/IR/SILFunctionType.cpp

@@ -1917,6 +1917,7 @@ lowerCaptureContextParameters(TypeConverter &TC, SILDeclRef function,
   // signature from the AST for that.
   auto origGenericSig = function.getAnyFunctionRef()->getGenericSignature();
   auto loweredCaptures = TC.getLoweredLocalCaptures(function);
+  auto *isolatedParam = loweredCaptures.getIsolatedParamCapture();
 
   for (auto capture : loweredCaptures.getCaptures()) {
     if (capture.isDynamicSelfMetadata()) {
@@ -1955,13 +1956,17 @@ lowerCaptureContextParameters(TypeConverter &TC, SILDeclRef function,
       continue;
     }
 
-    auto *VD = capture.getDecl();
-    auto type = VD->getInterfaceType();
+    auto *varDecl = capture.getDecl();
+    auto type = varDecl->getInterfaceType();
     auto canType = type->getReducedType(origGenericSig);
 
+    auto options = SILParameterInfo::Options();
+    if (isolatedParam == varDecl)
+      options |= SILParameterInfo::Isolated;
+
     // If we're capturing a parameter pack, wrap it in a tuple.
     if (isa<PackExpansionType>(canType)) {
-      assert(!cast<ParamDecl>(VD)->supportsMutation() &&
+      assert(!cast<ParamDecl>(varDecl)->supportsMutation() &&
              "Cannot capture a pack as an lvalue");
 
       SmallVector<TupleTypeElt, 1> elts;
@@ -1983,7 +1988,7 @@ lowerCaptureContextParameters(TypeConverter &TC, SILDeclRef function,
       } else {
         convention = ParameterConvention::Direct_Guaranteed;
       }
-      SILParameterInfo param(loweredTy.getASTType(), convention);
+      SILParameterInfo param(loweredTy.getASTType(), convention, options);
       inputs.push_back(param);
       break;
     }
@@ -1995,10 +2000,10 @@ lowerCaptureContextParameters(TypeConverter &TC, SILDeclRef function,
               .getLoweredType();
       // Lvalues are captured as a box that owns the captured value.
       auto boxTy = TC.getInterfaceBoxTypeForCapture(
-          VD, minimalLoweredTy.getASTType(),
+          varDecl, minimalLoweredTy.getASTType(),
           /*mutable*/ true);
       auto convention = ParameterConvention::Direct_Guaranteed;
-      auto param = SILParameterInfo(boxTy, convention);
+      auto param = SILParameterInfo(boxTy, convention, options);
       inputs.push_back(param);
       break;
     }
@@ -2009,20 +2014,20 @@ lowerCaptureContextParameters(TypeConverter &TC, SILDeclRef function,
                              TypeExpansionContext::minimal())
               .getLoweredType();
       // Lvalues are captured as a box that owns the captured value.
-      auto boxTy =
-          TC.getInterfaceBoxTypeForCapture(VD, minimalLoweredTy.getASTType(),
-                                           /*mutable*/ false);
+      auto boxTy = TC.getInterfaceBoxTypeForCapture(
+          varDecl, minimalLoweredTy.getASTType(),
+          /*mutable*/ false);
       auto convention = ParameterConvention::Direct_Guaranteed;
-      auto param = SILParameterInfo(boxTy, convention);
+      auto param = SILParameterInfo(boxTy, convention, options);
       inputs.push_back(param);
       break;
     }
     case CaptureKind::StorageAddress: {
       // Non-escaping lvalues are captured as the address of the value.
       SILType ty = loweredTy.getAddressType();
-      auto param =
-          SILParameterInfo(ty.getASTType(),
-                           ParameterConvention::Indirect_InoutAliasable);
+      auto param = SILParameterInfo(
+          ty.getASTType(), ParameterConvention::Indirect_InoutAliasable,
+          options);
       inputs.push_back(param);
       break;
     }
@@ -2030,9 +2035,9 @@ lowerCaptureContextParameters(TypeConverter &TC, SILDeclRef function,
       // 'let' constants that are address-only are captured as the address of
       // the value and will be consumed by the closure.
       SILType ty = loweredTy.getAddressType();
-      auto param =
-          SILParameterInfo(ty.getASTType(),
-                           ParameterConvention::Indirect_In_Guaranteed);
+      auto param = SILParameterInfo(ty.getASTType(),
+                                    ParameterConvention::Indirect_In_Guaranteed,
+                                    options);
       inputs.push_back(param);
       break;
     }

test/SILGen/isolated_self_capture.swift

@@ -0,0 +1,23 @@
+// RUN: %target-swift-frontend -emit-silgen %s -module-name test -swift-version 5 | %FileCheck %s
+
+// REQUIRES: concurrency
+
+class NonSendableKlass {}
+
+func useValue<T>(_ t: T) {}
+
+@MainActor func transferToMain<T>(_ t: T) async {}
+
+actor MyActor {
+  var ns = NonSendableKlass()
+
+  // CHECK-LABEL: sil hidden [ossa] @$s4test7MyActorC19passSelfIntoClosureyyYaF : $@convention(method) @async (@sil_isolated @guaranteed MyActor) -> () {
+  // CHECK: bb0([[ARG:%.*]] : @guaranteed $
+  // CHECK:   [[COPY:%.*]] = copy_value [[ARG]]
+  // CHECK:   [[PAI:%.*]] = partial_apply [callee_guaranteed] {{.*}}([[COPY]]) : $@convention(thin) (@sil_isolated @guaranteed MyActor) -> ()
+  // CHECK: } // end sil function '$s4test7MyActorC19passSelfIntoClosureyyYaF'
+  func passSelfIntoClosure() async {
+    let closure = { useValue(self.ns) }
+    await transferToMain(closure) 
+  }
+}