Allow declarations to opt in to suppressing @isolated(any).

Author: rjmccall

include/swift/AST/PrintOptions.h

@@ -376,11 +376,13 @@ struct PrintOptions {
   /// `AsyncIteratorProtocol` for backward-compatibility reasons.
   bool AsyncSequenceRethrows = false;
 
+  /// Suppress the @isolated(any) attribute.
+  bool SuppressIsolatedAny = false;
+
   /// List of attribute kinds that should not be printed.
   std::vector<AnyAttrKind> ExcludeAttrList = {
       DeclAttrKind::Transparent, DeclAttrKind::Effects,
       DeclAttrKind::FixedLayout, DeclAttrKind::ShowInInterface,
-      DeclAttrKind::AllowFeatureSuppression
   };
 
   /// List of attribute kinds that should be printed exclusively.

include/swift/Basic/Features.def

@@ -332,7 +332,7 @@ EXPERIMENTAL_FEATURE(DynamicActorIsolation, false)
 EXPERIMENTAL_FEATURE(BorrowingSwitch, true)
 
 // Enable isolated(any) attribute on function types.
-EXPERIMENTAL_FEATURE(IsolatedAny, true)
+CONDITIONALLY_SUPPRESSIBLE_EXPERIMENTAL_FEATURE(IsolatedAny, true)
 
 #undef EXPERIMENTAL_FEATURE_EXCLUDED_FROM_MODULE_INTERFACE
 #undef EXPERIMENTAL_FEATURE

lib/AST/ASTPrinter.cpp

@@ -367,6 +367,7 @@ PrintOptions PrintOptions::printSwiftInterfaceFile(ModuleDecl *ModuleToPrint,
       DeclAttrKind::StaticInitializeObjCMetadata,
       DeclAttrKind::RestatedObjCConformance,
       DeclAttrKind::NonSendable,
+      DeclAttrKind::AllowFeatureSuppression,
   };
 
   return result;
@@ -3907,6 +3908,12 @@ static bool usesFeatureIsolatedAny(Decl *decl) {
   });
 }
 
+static void suppressingFeatureIsolatedAny(PrintOptions &options,
+                                          llvm::function_ref<void()> action) {
+  llvm::SaveAndRestore<bool> scope(options.SuppressIsolatedAny, true);
+  action();
+}
+
 /// Suppress the printing of a particular feature.
 static void suppressingFeature(PrintOptions &options, Feature feature,
                                llvm::function_ref<void()> action) {
@@ -7236,7 +7243,8 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
       break;
 
     case FunctionTypeIsolation::Kind::Erased:
-      Printer << "@isolated(any) ";
+      if (!Options.SuppressIsolatedAny)
+        Printer << "@isolated(any) ";
       break;
     }
 

lib/AST/Attr.cpp

@@ -254,6 +254,13 @@ const char *IsolatedTypeAttr::getIsolationKindName(IsolationKind kind) {
 
 void IsolatedTypeAttr::printImpl(ASTPrinter &printer,
                                  const PrintOptions &options) const {
+  // Suppress the attribute if requested.
+  switch (getIsolationKind()) {
+  case IsolationKind::Dynamic:
+    if (options.SuppressIsolatedAny) return;
+    break;
+  }
+
   printer.callPrintStructurePre(PrintStructureKind::BuiltinAttribute);
   printer.printAttrName("@isolated");
   printer << "(" << getIsolationKindName() << ")";
@@ -1254,6 +1261,15 @@ bool DeclAttribute::printImpl(ASTPrinter &Printer, const PrintOptions &Options,
     Printer << "(" << cast<AlignmentAttr>(this)->getValue() << ")";
     break;
 
+  case DeclAttrKind::AllowFeatureSuppression:
+    Printer.printAttrName("@_allowFeatureSuppression");
+    Printer << "(";
+    interleave(cast<AllowFeatureSuppressionAttr>(this)->getSuppressedFeatures(),
+               [&](Identifier ident) { Printer << ident; },
+               [&] { Printer << ", "; });
+    Printer << ")";
+    break;
+
   case DeclAttrKind::SILGenName:
     Printer.printAttrName("@_silgen_name");
     Printer << "(\"" << cast<SILGenNameAttr>(this)->Name << "\")";

test/ModuleInterface/isolated_any_suppression.swift

@@ -0,0 +1,22 @@
+// RUN: %empty-directory(%t)
+
+// RUN: %target-swift-frontend -swift-version 5 -enable-library-evolution -module-name isolated_any -emit-module -o %t/isolated_any.swiftmodule -emit-module-interface-path -  -enable-experimental-feature IsolatedAny %s | %FileCheck %s
+
+// CHECK:      #if compiler(>=5.3) && $IsolatedAny
+// CHECK-NEXT: {{^}}public func test1(fn: @isolated(any) () -> ())
+// CHECK-NEXT: #endif
+public func test1(fn: @isolated(any) () -> ()) {}
+
+// CHECK-NEXT: #if compiler(>=5.3) && $IsolatedAny
+// CHECK-NEXT: {{^}}public func test2(fn: @isolated(any) () -> ())
+// CHECK-NEXT: #endif
+@_allowFeatureSuppression(XXX)
+public func test2(fn: @isolated(any) () -> ()) {}
+
+// CHECK-NEXT: #if compiler(>=5.3) && $IsolatedAny
+// CHECK-NEXT: {{^}}public func test3(fn: @isolated(any) () -> ())
+// CHECK-NEXT: #else
+// CHECK-NEXT: {{^}}public func test3(fn: () -> ())
+// CHECK-NEXT: #endif
+@_allowFeatureSuppression(IsolatedAny)
+public func test3(fn: @isolated(any) () -> ()) {}