[CoroutineAccessors] Initial framing.

docs/ABI/Mangling.rst

@@ -387,11 +387,13 @@ Entities
   ACCESSOR ::= 'G'                           // global getter
   ACCESSOR ::= 'w'                           // willSet
   ACCESSOR ::= 'W'                           // didSet
-  ACCESSOR ::= 'r'                           // read
-  ACCESSOR ::= 'M'                           // modify (temporary)
+  ACCESSOR ::= 'r'                           // _read
+  ACCESSOR ::= 'M'                           // _modify (temporary)
   ACCESSOR ::= 'a' ADDRESSOR-KIND            // mutable addressor
   ACCESSOR ::= 'l' ADDRESSOR-KIND            // non-mutable addressor
   ACCESSOR ::= 'p'                           // pseudo accessor referring to the storage itself
+  ACCESSOR ::= 'x'                           // modify
+  ACCESSOR ::= 'y'                           // read
 
   ADDRESSOR-KIND ::= 'u'                     // unsafe addressor (no owner)
   ADDRESSOR-KIND ::= 'O'                     // owning addressor (non-native owner), not used anymore

include/swift/ABI/MetadataValues.h

@@ -372,6 +372,8 @@ class MethodDescriptorFlags {
     Setter,
     ModifyCoroutine,
     ReadCoroutine,
+    Read2Coroutine,
+    Modify2Coroutine,
   };
 
 private:
@@ -594,6 +596,8 @@ class ProtocolRequirementFlags {
     ModifyCoroutine,
     AssociatedTypeAccessFunction,
     AssociatedConformanceAccessFunction,
+    Read2Coroutine,
+    Modify2Coroutine,
   };
 
 private:

include/swift/AST/AccessorKinds.def

@@ -73,6 +73,14 @@
 #define COROUTINE_ACCESSOR(ID, KEYWORD) OPAQUE_ACCESSOR(ID, KEYWORD)
 #endif
 
+/// EXPERIMENTAL_COROUTINE_ACCESSOR(ID, KEYWORD, FEATURE)
+///   The given coroutine accessor is experimental.
+///
+///   Defaults to COROUTINE_ACCESSOR(ID, KEYWORD)
+#ifndef EXPERIMENTAL_COROUTINE_ACCESSOR
+#define EXPERIMENTAL_COROUTINE_ACCESSOR(ID, KEYWORD, FEATURE) COROUTINE_ACCESSOR(ID, KEYWORD)
+#endif
+
 /// ANY_ADDRESSOR(ID, KEYWORD)
 ///   The given keyword corresponds to an addressor of the given kind.
 ///
@@ -108,11 +116,6 @@
 #define INIT_ACCESSOR(ID, KEYWORD) SINGLETON_ACCESSOR(ID, KEYWORD)
 #endif
 
-// Suppress entries for accessors which can't be written in source code.
-#ifndef SUPPRESS_ARTIFICIAL_ACCESSORS
-#define SUPPRESS_ARTIFICIAL_ACCESSORS 0
-#endif
-
 /// This is a getter: a function that is called when a value is loaded
 /// from the storage.  It returns an owned value of the storage type.
 ///
@@ -150,6 +153,14 @@ OBJC_ACCESSOR(Set, set)
 /// one can always be synthesized (even if the storage type is move-only).
 COROUTINE_ACCESSOR(Read, _read)
 
+/// This is a read accessor: a yield-once coroutine which is called when a
+/// value is loaded from the storage, like a getter, but which works
+/// by yielding a borrowed value of the storage type.
+///
+/// If the storage is not implemented with a read accessor then
+/// one can always be synthesized (even if the storage type is move-only).
+EXPERIMENTAL_COROUTINE_ACCESSOR(Read2, read, CoroutineAccessors)
+
 /// This is a modify accessor: a yield-once coroutine which is called when a
 /// the storage is modified which works by yielding an inout value
 /// of the storage type.
@@ -158,6 +169,14 @@ COROUTINE_ACCESSOR(Read, _read)
 /// one can be synthesized if the storage is mutable at all.
 COROUTINE_ACCESSOR(Modify, _modify)
 
+/// This is a modify accessor: a yield-once coroutine which is called when a
+/// the storage is modified which works by yielding an inout value
+/// of the storage type.
+///
+/// If the storage is not implemented with a modify accessor then
+/// one can be synthesized if the storage is mutable at all.
+EXPERIMENTAL_COROUTINE_ACCESSOR(Modify2, modify, CoroutineAccessors)
+
 /// This is a willSet observer: a function which "decorates" an
 /// underlying assignment operation by being called prior to the
 /// operation when a value is assigned to the storage.
@@ -210,6 +229,7 @@ LAST_ACCESSOR(Init)
 #undef OBJC_ACCESSOR
 #undef OPAQUE_ACCESSOR
 #undef COROUTINE_ACCESSOR
+#undef EXPERIMENTAL_COROUTINE_ACCESSOR
 #undef OBSERVING_ACCESSOR
 #undef SINGLETON_ACCESSOR
 #undef ACCESSOR

include/swift/AST/AnyFunctionRef.h

@@ -260,9 +260,10 @@ class AnyFunctionRef {
                                          ->getReferenceStorageReferent();
           if (mapIntoContext)
             valueTy = AD->mapTypeIntoContext(valueTy);
-          YieldTypeFlags flags(AD->getAccessorKind() == AccessorKind::Modify
-                                 ? ParamSpecifier::InOut
-                                 : ParamSpecifier::LegacyShared);
+          YieldTypeFlags flags(
+              isYieldingDefaultMutatingAccessor(AD->getAccessorKind())
+                  ? ParamSpecifier::InOut
+                  : ParamSpecifier::LegacyShared);
           buffer.push_back(AnyFunctionType::Yield(valueTy, flags));
           return buffer;
         }
@@ -304,4 +305,3 @@ struct DenseMapInfo<swift::AnyFunctionRef> {
 }
 
 #endif // LLVM_SWIFT_AST_ANY_FUNCTION_REF_H
-

include/swift/AST/DiagnosticsParse.def

@@ -305,6 +305,9 @@ ERROR(observing_accessor_in_subscript,none,
       "%select{'willSet'|'didSet'}0 is not allowed in subscripts", (unsigned))
 ERROR(getset_cannot_be_implied,none,
       "variable with implied type cannot have implied getter/setter", ())
+ERROR(accessor_requires_coroutine_accessors,none,
+      "%0 is only valid when experimental feature coroutine accessors is enabled",
+      (StringRef))
 
 // Import
 ERROR(decl_expected_module_name,none,

include/swift/AST/DiagnosticsSema.def

@@ -1710,9 +1710,10 @@ ERROR(functions_mutating_and_not,none,
 ERROR(static_functions_not_mutating,none,
       "static functions must not be declared mutating", ())
 
-ERROR(modify_mutatingness_differs_from_setter,none,
-      "'modify' accessor cannot be %0 when the setter is %1",
-      (SelfAccessKind, SelfAccessKind))
+ERROR(readwriter_mutatingness_differs_from_reader_or_writer_mutatingness,none,
+      "%0 cannot be %1 when "
+      "%select{both the %3 is %4 and the %5 is not %6|either the %3 is not %4 or the %5 is %6|the %3 is not %4|the %5 is %6}2",
+      (StringRef, SelfAccessKind, unsigned, StringRef, SelfAccessKind, StringRef, SelfAccessKind))
 
 ERROR(transparent_in_protocols_not_supported,none,
       "'@_transparent' attribute is not supported on declarations within protocols", ())
@@ -6584,8 +6585,8 @@ ERROR(dynamic_with_transparent,none,
 ERROR(dynamic_replacement_accessor_not_dynamic, none,
       "replaced accessor for %0 is not marked dynamic", (DeclName))
 ERROR(dynamic_replacement_accessor_not_explicit, none,
-      "replaced accessor %select{get|set|_read|_modify|willSet|didSet|unsafeAddress|addressWithOwner|addressWithNativeOwner|unsafeMutableAddress|mutableAddressWithOwner|}0 for %1 is not explicitly defined",
-      (unsigned, DeclName))
+      "replaced %0 for %1 is not explicitly defined",
+      (StringRef, DeclName))
 ERROR(dynamic_replacement_function_not_dynamic, none,
       "replaced function %0 is not marked dynamic", (DeclName))
 ERROR(dynamic_replacement_function_not_found, none,

include/swift/AST/PrintOptions.h

@@ -390,6 +390,9 @@ struct PrintOptions {
   /// Suppress ~Escapable types and lifetime dependence annotations
   bool SuppressNonEscapableTypes = false;
 
+  /// Suppress modify/read accessors.
+  bool SuppressCoroutineAccessors = false;
+
   /// List of attribute kinds that should not be printed.
   std::vector<AnyAttrKind> ExcludeAttrList = {
       DeclAttrKind::Transparent, DeclAttrKind::Effects,