[Sema] NFC: Add a variant of addNonIsolatedToSynthesized that checks for @preconcurrency conformances

If derived conformance is marked as `@preconcurrency` instead of
marking synthesized members as `nonisolated` the compiler should
insert dynamic checks.

Author: xedin

lib/Sema/CodeSynthesis.cpp

@@ -21,6 +21,7 @@
 #include "TypeCheckObjC.h"
 #include "TypeCheckType.h"
 #include "TypeChecker.h"
+#include "DerivedConformances.h"
 #include "swift/AST/ASTMangler.h"
 #include "swift/AST/ASTPrinter.h"
 #include "swift/AST/AvailabilityInference.h"
@@ -1728,6 +1729,15 @@ bool swift::hasLetStoredPropertyWithInitialValue(NominalTypeDecl *nominal) {
   });
 }
 
+bool swift::addNonIsolatedToSynthesized(DerivedConformance &derived,
+                                        ValueDecl *value) {
+  if (auto *conformance = derived.Conformance) {
+    if (conformance && conformance->isPreconcurrency())
+      return false;
+  }
+  return addNonIsolatedToSynthesized(derived.Nominal, value);
+}
+
 bool swift::addNonIsolatedToSynthesized(NominalTypeDecl *nominal,
                                         ValueDecl *value) {
   if (!getActorIsolation(nominal).isActorIsolated())

lib/Sema/CodeSynthesis.h

@@ -41,6 +41,7 @@ class ParamDecl;
 class Type;
 class ValueDecl;
 class VarDecl;
+class DerivedConformance;
 
 enum class SelfAccessorKind {
   /// We're building a derived accessor on top of whatever this
@@ -85,6 +86,11 @@ ValueDecl *getProtocolRequirement(ProtocolDecl *protocol, Identifier name);
 // with an initial value.
 bool hasLetStoredPropertyWithInitialValue(NominalTypeDecl *nominal);
 
+/// Add 'nonisolated' to the synthesized declaration for a derived
+/// conformance when needed. Returns true if an attribute was added.
+bool addNonIsolatedToSynthesized(DerivedConformance &conformance,
+                                 ValueDecl *value);
+
 /// Add 'nonisolated' to the synthesized declaration when needed. Returns true
 /// if an attribute was added.
 bool addNonIsolatedToSynthesized(NominalTypeDecl *nominal, ValueDecl *value);