[CoroutineAccessors] Separate requires predicates.

Whether read2/modify2 are required will not always be identical to
whether read/modify are required.  Add separate prediates for the
former.  For now, duplicate the latter's implementation.

Author: nate-chandler

include/swift/AST/Decl.h

@@ -6032,13 +6032,20 @@ class AbstractStorageDecl : public ValueDecl {
   /// Does this storage require a '_read' accessor in its opaque-accessors set?
   bool requiresOpaqueReadCoroutine() const;
 
+  /// Does this storage require a 'read' accessor in its opaque-accessors set?
+  bool requiresOpaqueRead2Coroutine() const;
+
   /// Does this storage require a 'set' accessor in its opaque-accessors set?
   bool requiresOpaqueSetter() const { return supportsMutation(); }
 
   /// Does this storage require a '_modify' accessor in its opaque-accessors
   /// set?
   bool requiresOpaqueModifyCoroutine() const;
 
+  /// Does this storage require a 'modify' accessor in its opaque-accessors
+  /// set?
+  bool requiresOpaqueModify2Coroutine() const;
+
   /// Does this storage have any explicit observers (willSet or didSet) attached
   /// to it?
   bool hasObservers() const {

lib/AST/Decl.cpp

@@ -2990,11 +2990,13 @@ bool AbstractStorageDecl::requiresOpaqueAccessor(AccessorKind kind) const {
   case AccessorKind::Set:
     return requiresOpaqueSetter();
   case AccessorKind::Read:
-  case AccessorKind::Read2:
     return requiresOpaqueReadCoroutine();
+  case AccessorKind::Read2:
+    return requiresOpaqueRead2Coroutine();
   case AccessorKind::Modify:
-  case AccessorKind::Modify2:
     return requiresOpaqueModifyCoroutine();
+  case AccessorKind::Modify2:
+    return requiresOpaqueModify2Coroutine();
 
   // Other accessors are never part of the opaque-accessors set.
 #define OPAQUE_ACCESSOR(ID, KEYWORD)
@@ -3010,13 +3012,30 @@ bool AbstractStorageDecl::requiresOpaqueReadCoroutine() const {
   return getOpaqueReadOwnership() != OpaqueReadOwnership::Owned;
 }
 
+bool AbstractStorageDecl::requiresOpaqueRead2Coroutine() const {
+  ASTContext &ctx = getASTContext();
+  if (!ctx.LangOpts.hasFeature(Feature::CoroutineAccessors))
+    return false;
+  return getOpaqueReadOwnership() != OpaqueReadOwnership::Owned;
+}
+
 bool AbstractStorageDecl::requiresOpaqueModifyCoroutine() const {
   ASTContext &ctx = getASTContext();
   return evaluateOrDefault(ctx.evaluator,
     RequiresOpaqueModifyCoroutineRequest{const_cast<AbstractStorageDecl *>(this)},
     false);
 }
 
+bool AbstractStorageDecl::requiresOpaqueModify2Coroutine() const {
+  ASTContext &ctx = getASTContext();
+  if (!ctx.LangOpts.hasFeature(Feature::CoroutineAccessors))
+    return false;
+  return evaluateOrDefault(ctx.evaluator,
+                           RequiresOpaqueModifyCoroutineRequest{
+                               const_cast<AbstractStorageDecl *>(this)},
+                           false);
+}
+
 AccessorDecl *AbstractStorageDecl::getSynthesizedAccessor(AccessorKind kind) const {
   if (auto *accessor = getAccessor(kind))
     return accessor;