Enable NonEscapableTypes in standard library and make the feature suppressible

include/swift/AST/PrintOptions.h

@@ -387,6 +387,9 @@ struct PrintOptions {
   /// Replace BitwiseCopyable with _BitwiseCopyable.
   bool SuppressBitwiseCopyable = false;
 
+  /// Suppress ~Escapable types and lifetime dependence annotations
+  bool SuppressNonEscapableTypes = false;
+
   /// List of attribute kinds that should not be printed.
   std::vector<AnyAttrKind> ExcludeAttrList = {
       DeclAttrKind::Transparent, DeclAttrKind::Effects,

include/swift/Basic/Features.def

@@ -358,7 +358,7 @@ EXPERIMENTAL_FEATURE(StructLetDestructuring, true)
 
 /// Enable non-escapable type attributes and function attributes that support
 /// lifetime-dependent results.
-EXPERIMENTAL_FEATURE(NonescapableTypes, true)
+SUPPRESSIBLE_EXPERIMENTAL_FEATURE(NonescapableTypes, true)
 
 /// Enable the `@_staticExclusiveOnly` attribute.
 EXPERIMENTAL_FEATURE(StaticExclusiveOnly, true)

lib/AST/ASTPrinter.cpp

@@ -1978,6 +1978,11 @@ void PrintAST::printSingleDepthOfGenericSignature(
       if (dependsOnOpaque(inverse.subject))
         continue;
 
+      if (inverse.getKind() == InvertibleProtocolKind::Escapable &&
+          Options.SuppressNonEscapableTypes) {
+        continue;
+      }
+
       if (isFirstReq) {
         if (printRequirements)
           Printer << " " << tok::kw_where << " ";
@@ -3099,6 +3104,16 @@ suppressingFeatureAllowUnsafeAttribute(PrintOptions &options,
   options.ExcludeAttrList.resize(originalExcludeAttrCount);
 }
 
+static void
+suppressingFeatureNonescapableTypes(PrintOptions &options,
+                                    llvm::function_ref<void()> action) {
+  unsigned originalExcludeAttrCount = options.ExcludeAttrList.size();
+  options.ExcludeAttrList.push_back(DeclAttrKind::Lifetime);
+  llvm::SaveAndRestore<bool> scope(options.SuppressNonEscapableTypes, true);
+  action();
+  options.ExcludeAttrList.resize(originalExcludeAttrCount);
+}
+
 /// Suppress the printing of a particular feature.
 static void suppressingFeature(PrintOptions &options, Feature feature,
                                llvm::function_ref<void()> action) {
@@ -4107,10 +4122,12 @@ void PrintAST::visitFuncDecl(FuncDecl *decl) {
       Printer.printDeclResultTypePre(decl, ResultTyLoc);
       Printer.callPrintStructurePre(PrintStructureKind::FunctionReturnType);
       {
-        if (auto *typeRepr = dyn_cast_or_null<LifetimeDependentTypeRepr>(
-                decl->getResultTypeRepr())) {
-          for (auto &dep : typeRepr->getLifetimeDependencies()) {
-            Printer << " " << dep.getDependsOnString() << " ";
+        if (!Options.SuppressNonEscapableTypes) {
+          if (auto *typeRepr = dyn_cast_or_null<LifetimeDependentTypeRepr>(
+                  decl->getResultTypeRepr())) {
+            for (auto &dep : typeRepr->getLifetimeDependencies()) {
+              Printer << " " << dep.getDependsOnString() << " ";
+            }
           }
         }
       }
@@ -4330,15 +4347,17 @@ void PrintAST::visitConstructorDecl(ConstructorDecl *decl) {
 
       printGenericDeclGenericParams(decl);
       printFunctionParameters(decl);
-      if (decl->hasLifetimeDependentReturn()) {
-        Printer << " -> ";
-        auto *typeRepr =
-            cast<LifetimeDependentTypeRepr>(decl->getResultTypeRepr());
-        for (auto &dep : typeRepr->getLifetimeDependencies()) {
-          Printer << dep.getDependsOnString() << " ";
+      if (!Options.SuppressNonEscapableTypes) {
+        if (decl->hasLifetimeDependentReturn()) {
+          Printer << " -> ";
+          auto *typeRepr =
+              cast<LifetimeDependentTypeRepr>(decl->getResultTypeRepr());
+          for (auto &dep : typeRepr->getLifetimeDependencies()) {
+            Printer << dep.getDependsOnString() << " ";
+          }
+          // TODO: Handle failable initializers with lifetime dependent returns
+          Printer << "Self";
         }
-        // TODO: Handle failable initializers with lifetime dependent returns
-        Printer << "Self";
       }
     });
 
@@ -7796,7 +7815,28 @@ swift::getInheritedForPrinting(
         }
         continue;
       }
+
+      // Suppress Escapable and ~Escapable.
+      if (options.SuppressNonEscapableTypes) {
+        if (auto pct = ty->getAs<ProtocolCompositionType>()) {
+          auto inverses = pct->getInverses();
+          if (inverses.contains(InvertibleProtocolKind::Escapable)) {
+            inverses.remove(InvertibleProtocolKind::Escapable);
+            ty = ProtocolCompositionType::get(decl->getASTContext(),
+                                              pct->getMembers(), inverses,
+                                              pct->hasExplicitAnyObject());
+            if (ty->isAny())
+              continue;
+          }
+        }
+
+        if (auto protoTy = ty->getAs<ProtocolType>())
+          if (protoTy->getDecl()->isSpecificProtocol(
+                  KnownProtocolKind::Escapable))
+            continue;
+      }
     }
+
     if (options.SuppressConformanceSuppression &&
         inherited.getEntry(i).isSuppressed()) {
       continue;

lib/AST/FeatureSet.cpp

@@ -130,7 +130,75 @@ UNINTERESTING_FEATURE(Embedded)
 UNINTERESTING_FEATURE(Volatile)
 UNINTERESTING_FEATURE(SuppressedAssociatedTypes)
 UNINTERESTING_FEATURE(StructLetDestructuring)
-UNINTERESTING_FEATURE(NonescapableTypes)
+
+static bool usesFeatureNonescapableTypes(Decl *decl) {
+  auto containsNonEscapable =
+      [](SmallVectorImpl<InverseRequirement> &inverseReqs) {
+        auto foundIt =
+            llvm::find_if(inverseReqs, [](InverseRequirement inverseReq) {
+              if (inverseReq.getKind() == InvertibleProtocolKind::Escapable) {
+                return true;
+              }
+              return false;
+            });
+        return foundIt != inverseReqs.end();
+      };
+
+  if (auto *valueDecl = dyn_cast<ValueDecl>(decl)) {
+    if (isa<StructDecl, EnumDecl, ClassDecl>(decl)) {
+      auto *nominalDecl = cast<NominalTypeDecl>(valueDecl);
+      InvertibleProtocolSet inverses;
+      bool anyObject = false;
+      getDirectlyInheritedNominalTypeDecls(nominalDecl, inverses, anyObject);
+      if (inverses.containsEscapable()) {
+        return true;
+      }
+    }
+
+    if (auto proto = dyn_cast<ProtocolDecl>(decl)) {
+      auto reqSig = proto->getRequirementSignature();
+
+      SmallVector<Requirement, 2> reqs;
+      SmallVector<InverseRequirement, 2> inverses;
+      reqSig.getRequirementsWithInverses(proto, reqs, inverses);
+      if (containsNonEscapable(inverses))
+        return true;
+    }
+
+    if (isa<AbstractFunctionDecl>(valueDecl) ||
+        isa<AbstractStorageDecl>(valueDecl)) {
+      if (valueDecl->getInterfaceType().findIf([&](Type type) -> bool {
+            if (auto *nominalDecl = type->getAnyNominal()) {
+              if (isa<StructDecl, EnumDecl, ClassDecl>(nominalDecl))
+                return usesFeatureNonescapableTypes(nominalDecl);
+            }
+            return false;
+          })) {
+        return true;
+      }
+    }
+  }
+
+  if (auto *ext = dyn_cast<ExtensionDecl>(decl)) {
+    if (auto *nominal = ext->getExtendedNominal())
+      if (usesFeatureNonescapableTypes(nominal))
+        return true;
+  }
+
+  if (auto *genCtx = decl->getAsGenericContext()) {
+    if (auto genericSig = genCtx->getGenericSignature()) {
+      SmallVector<Requirement, 2> reqs;
+      SmallVector<InverseRequirement, 2> inverseReqs;
+      genericSig->getRequirementsWithInverses(reqs, inverseReqs);
+      if (containsNonEscapable(inverseReqs)) {
+        return true;
+      }
+    }
+  }
+
+  return false;
+}
+
 UNINTERESTING_FEATURE(StaticExclusiveOnly)
 UNINTERESTING_FEATURE(ExtractConstantsFromMembers)
 UNINTERESTING_FEATURE(FixedArrays)

stdlib/cmake/modules/SwiftSource.cmake

@@ -630,9 +630,7 @@ function(_compile_swift_files
   list(APPEND swift_flags "-enable-experimental-feature" "SE427NoInferenceOnExtension")
   list(APPEND swift_flags "-enable-experimental-feature" "AllowUnsafeAttribute")
 
-  if(SWIFT_ENABLE_EXPERIMENTAL_NONESCAPABLE_TYPES)
-    list(APPEND swift_flags "-enable-experimental-feature" "NonescapableTypes")
-  endif()
+  list(APPEND swift_flags "-enable-experimental-feature" "NonescapableTypes")
 
   list(APPEND swift_flags "-enable-experimental-feature" "ExtensionImportVisiblity")
 

test/ModuleInterface/noncopyable_generics.swift

@@ -117,7 +117,11 @@ import NoncopyableGenerics_Misc
 // CHECK-MISC: extension {{.*}}.Outer.InnerVariation2 : Swift.Escapable where D : Swift.Escapable {
 
 // CHECK-MISC: extension {{.*}}.Outer.InnerStruct {
+// CHECK-MISC-NEXT: #if compiler(>=5.3) && $NonescapableTypes
 // CHECK-MISC-NEXT:   public func hello<T>(_ t: T) where T : ~Escapable
+// CHECK-MISC-NEXT:   #else
+// CHECK-MISC-NEXT:   public func hello<T>(_ t: T)
+// CHECK-MISC-NEXT:   #endif
 
 // CHECK-MISC: @_preInverseGenerics public func old_swap<T>(_ a: inout T, _ b: inout T) where T : ~Copyable
 

test/ModuleInterface/nonescapable_types.swift

@@ -0,0 +1,88 @@
+// RUN: %empty-directory(%t)
+ // RUN: %target-swift-emit-module-interface(%t.swiftinterface) %s -module-name Test -enable-experimental-feature NonescapableTypes
+ // RUN: %target-swift-typecheck-module-from-interface(%t.swiftinterface) -module-name Test
+ // RUN: %FileCheck %s < %t.swiftinterface
+
+ // CHECK: #if compiler(>=5.3) && $NonescapableTypes
+ // CHECK: public protocol P : ~Escapable {
+ // CHECK:   associatedtype A
+ // CHECK: }
+ // CHECK: #else
+ // CHECK: public protocol P {
+ // CHECK:   associatedtype A
+ // CHECK: }
+ // CHECK: #endif
+ public protocol P: ~Escapable {
+   associatedtype A
+ }
+
+ // CHECK: #if compiler(>=5.3) && $NonescapableTypes
+ // CHECK: public struct X<T> : ~Swift.Escapable where T : ~Escapable {
+ // CHECK: }
+ // CHECK: #else
+ // CHECK: public struct X<T> {
+ // CHECK: }
+ // CHECK: #endif
+ public struct X<T: ~Escapable>: ~Escapable { }
+
+ // CHECK: #if compiler(>=5.3) && $NonescapableTypes
+ // CHECK:      extension Test.X {
+ // CHECK-NEXT:   func f()
+ // CHECK:      }
+ // CHECK: #else
+ // CHECK:      extension Test.X {
+ // CHECK-NEXT:   func f()
+ // CHECK:      }
+ extension X where T: Escapable {
+   public func f() { }
+ }
+
+ // CHECK: #if compiler(>=5.3) && $NonescapableTypes
+ // CHECK: extension Test.X where T : ~Escapable {
+ // CHECK:   public func g(other: borrowing T)
+ // CHECK: }
+ // CHECK: #else
+ // CHECK: extension Test.X {
+ // CHECK:   public func g(other: borrowing T)
+ // CHECK: }
+ // CHECK: #endif
+ extension X where T: ~Escapable {
+   public func g(other: borrowing T) { }
+ }
+
+ // CHECK: #if compiler(>=5.3) && $NonescapableTypes
+ // CHECK: public enum Y<T> : ~Swift.Escapable where T : ~Escapable {
+ // CHECK:   case none
+ // CHECK:   case some(T)
+ // CHECK: }
+ // CHECK: #else
+ // CHECK: public enum Y<T> {
+ // CHECK:   case none
+ // CHECK:   case some(T)
+ // CHECK: }
+ public enum Y<T: ~Escapable>: ~Escapable {
+   case none
+   case some(T)
+ }
+
+ extension Y: Escapable where T: Escapable { }
+
+ // CHECK: #if compiler(>=5.3) && $NonescapableTypes
+ // CHECK: @lifetime(y)
+ // CHECK: public func derive<T>(_ y: Test.Y<T>) -> Test.Y<T> where T : ~Escapable
+ // CHECK: #else
+ // CHECK: public func derive<T>(_ y: Test.Y<T>) -> Test.Y<T>
+ // CHECK: #endif
+ @lifetime(y)
+ public func derive<T : ~Escapable>(_ y: Y<T>) -> Y<T> {
+   y
+ }
+
+ // CHECK: #if compiler(>=5.3) && $NonescapableTypes
+ // CHECK: public func derive<T>(_ x: Test.X<T>) -> dependsOn(x) Test.X<T> where T : ~Escapable
+ // CHECK: #else
+ // CHECK: public func derive<T>(_ x: Test.X<T>) -> Test.X<T>
+ // CHECK: #endif
+ public func derive<T : ~Escapable>(_ x: X<T>) -> dependsOn(x) X<T> {
+   x
+ }