[Concurrency] Always diagnose invalid isolated parameter types in type resolution.

include/swift/AST/DiagnosticsSema.def

@@ -5528,10 +5528,8 @@ NOTE(protocol_isolated_to_global_actor_here,none,
      "%0 is isolated to global actor %1 here", (Type, Type))
 
 ERROR(isolated_parameter_not_actor,none,
-      "'isolated' parameter has non-actor type %0", (Type))
-ERROR(isolated_parameter_no_actor_conformance,none,
-      "'isolated' parameter %0 must conform to 'Actor' "
-      "or 'DistributedActor' protocol", (Type))
+      "'isolated' parameter type %0 does not conform to 'Actor' "
+      "or 'DistributedActor'", (Type))
 ERROR(isolated_parameter_duplicate,none,
       "cannot have more than one 'isolated' parameter", ())
 ERROR(isolated_parameter_duplicate_type,none,

lib/Sema/TypeCheckConcurrency.cpp

@@ -4759,27 +4759,8 @@ ActorIsolation ActorIsolationRequest::evaluate(
     checkDeclWithIsolatedParameter(value);
 
     ParamDecl *param = getParameterList(value)->get(*paramIdx);
-    Type paramType = param->getInterfaceType();
-    if (paramType->isTypeParameter()) {
-      paramType = param->getDeclContext()->mapTypeIntoContext(paramType);
-
-      auto &ctx = value->getASTContext();
-      auto conformsTo = [&](KnownProtocolKind kind) {
-        if (auto *proto = ctx.getProtocol(kind))
-          return value->getModuleContext()->checkConformance(paramType, proto);
-        return ProtocolConformanceRef::forInvalid();
-      };
-
-      // The type parameter must be bound by Actor or DistributedActor, as they
-      // have an unownedExecutor. AnyActor does NOT have an unownedExecutor!
-      if (!conformsTo(KnownProtocolKind::Actor)
-          && !conformsTo(KnownProtocolKind::DistributedActor)) {
-        ctx.Diags.diagnose(param->getLoc(),
-                           diag::isolated_parameter_no_actor_conformance,
-                           paramType);
-      }
-    }
-
+    Type paramType = param->getDeclContext()->mapTypeIntoContext(
+        param->getInterfaceType());
     Type actorType;
     if (auto wrapped = paramType->getOptionalObjectType()) {
       actorType = wrapped;

lib/Sema/TypeCheckType.cpp

@@ -3927,18 +3927,6 @@ NeverNullType TypeResolver::resolveASTFunctionType(
       repr->setWarned();
   }
 
-  // Use parameter isolation if we have any.  This overrides all other
-  // forms (and should cause conflict diagnostics).
-  if (numIsolatedParams > 0) {
-    isolation = FunctionTypeIsolation::forParameter();
-
-    if (isolatedAttr) {
-      diagnose(repr->getLoc(), diag::isolated_parameter_isolated_attr_type,
-               isolatedAttr->getIsolationKindName());
-      isolatedAttr->setInvalid();
-    }
-  }
-
   if (attrs) {
     CustomAttr *globalActorAttr = nullptr;
     Type globalActor = resolveGlobalActor(repr->getLoc(), parentOptions,
@@ -3996,6 +3984,18 @@ NeverNullType TypeResolver::resolveASTFunctionType(
   auto params =
       resolveASTFunctionTypeParams(repr->getArgsTypeRepr(), options, diffKind);
 
+  // Use parameter isolation if we have any.  This overrides all other
+  // forms (and should cause conflict diagnostics).
+  if (hasIsolatedParameter(params)) {
+    isolation = FunctionTypeIsolation::forParameter();
+
+    if (isolatedAttr) {
+      diagnose(repr->getLoc(), diag::isolated_parameter_isolated_attr_type,
+               isolatedAttr->getIsolationKindName());
+      isolatedAttr->setInvalid();
+    }
+  }
+
   auto resultOptions = options.withoutContext();
   resultOptions.setContext(TypeResolverContext::FunctionResult);
   auto outputTy = resolveType(repr->getResultTypeRepr(), resultOptions);
@@ -4891,14 +4891,18 @@ TypeResolver::resolveIsolatedTypeRepr(IsolatedTypeRepr *repr,
   if (auto dynamicSelfType = dyn_cast<DynamicSelfType>(unwrappedType)) {
     unwrappedType = dynamicSelfType->getSelfType();
   }
+  // here
 
-  // isolated parameters must be of actor type
-  if (!unwrappedType->isTypeParameter() &&
-      !unwrappedType->isAnyActorType() &&
-      !unwrappedType->hasError()) {
-    diagnoseInvalid(
-        repr, repr->getSpecifierLoc(), diag::isolated_parameter_not_actor, type);
-    return ErrorType::get(type);
+  if (inStage(TypeResolutionStage::Interface)) {
+    if (auto *env = resolution.getGenericSignature().getGenericEnvironment())
+      unwrappedType = env->mapTypeIntoContext(unwrappedType);
+
+    if (!unwrappedType->isAnyActorType() && !unwrappedType->hasError()) {
+      diagnoseInvalid(
+          repr, repr->getSpecifierLoc(),
+          diag::isolated_parameter_not_actor, type);
+      return ErrorType::get(type);
+    }
   }
 
   return type;

test/Concurrency/isolated_parameters.swift

@@ -20,7 +20,7 @@ extension Actor {
 func testA<T: Actor>(
   a: isolated A,  // expected-note{{previous 'isolated' parameter 'a'}}
   b: isolated T,  // expected-warning{{cannot have more than one 'isolated' parameter; this is an error in Swift 6}}
-  c: isolated Int // expected-error {{'isolated' parameter has non-actor type 'Int'}}
+  c: isolated Int // expected-error {{'isolated' parameter type 'Int' does not conform to 'Actor' or 'DistributedActor'}}
 ) {
   a.f()
   a.g()
@@ -350,14 +350,14 @@ func getValues(
 }
 
 func isolated_generic_bad_1<T>(_ t: isolated T) {}
-// expected-error@-1 {{'isolated' parameter 'T' must conform to 'Actor' or 'DistributedActor' protocol}}
+// expected-error@-1 {{'isolated' parameter type 'T' does not conform to 'Actor' or 'DistributedActor'}}
 func isolated_generic_bad_2<T: Equatable>(_ t: isolated T) {}
-// expected-error@-1 {{'isolated' parameter 'T' must conform to 'Actor' or 'DistributedActor' protocol}}
+// expected-error@-1 {{'isolated' parameter type 'T' does not conform to 'Actor' or 'DistributedActor'}}
 func isolated_generic_bad_3<T: AnyActor>(_ t: isolated T) {}
-// expected-error@-1 {{'isolated' parameter 'T' must conform to 'Actor' or 'DistributedActor' protocol}}
+// expected-error@-1 {{'isolated' parameter type 'T' does not conform to 'Actor' or 'DistributedActor'}}
 
 func isolated_generic_bad_4<T>(_ t: isolated Array<T>) {}
-// expected-error@-1 {{'isolated' parameter has non-actor type 'Array<T>'}}
+// expected-error@-1 {{'isolated' parameter type 'Array<T>' does not conform to 'Actor' or 'DistributedActor'}}
 
 func isolated_generic_ok_1<T: Actor>(_ t: isolated T) {}
 
@@ -473,3 +473,7 @@ func preciseIsolated(a: isolated MyActor) async {
 nonisolated func fromNonisolated(ns: NotSendable) async -> NotSendable {
   await pass(value: ns, isolation: nil)
 }
+
+func invalidIsolatedClosureParam<A: AnyActor> (
+  _: (isolated A) async throws -> Void // expected-error {{'isolated' parameter type 'A' does not conform to 'Actor' or 'DistributedActor'}}
+) {}