Parse: Simpler handling of 'class' in protocol inheritance list

Instead of treating this as its own thing, just parse it as if
the user wrote 'AnyObject'.

Author: slavapestov

include/swift/AST/Decl.h

@@ -3489,9 +3489,6 @@ struct SelfReferenceKind {
 class ProtocolDecl final : public NominalTypeDecl {
   SourceLoc ProtocolLoc;
 
-  /// The location of the 'class' keyword for class-bound protocols.
-  SourceLoc ClassRequirementLoc;
-
   /// The syntactic representation of the where clause in a protocol like
   /// `protocol ... where ... { ... }`.
   TrailingWhereClause *TrailingWhere;
@@ -3571,17 +3568,6 @@ class ProtocolDecl final : public NominalTypeDecl {
     ProtocolDeclBits.RequiresClass = requiresClass;
   }
 
-  /// Specify that this protocol is class-bounded, recording the location of
-  /// the 'class' keyword.
-  void setClassBounded(SourceLoc loc) {
-    ClassRequirementLoc = loc;
-    ProtocolDeclBits.RequiresClassValid = true;
-    ProtocolDeclBits.RequiresClass = true;
-  }
-
-  /// Retrieve the source location of the 'class' keyword.
-  SourceLoc getClassBoundedLoc() const { return ClassRequirementLoc; }
-
   /// Determine whether an existential conforming to this protocol can be
   /// matched with a generic type parameter constrained to this protocol.
   /// This is only permitted if there is nothing "non-trivial" that we

include/swift/Parse/Parser.h

@@ -773,7 +773,7 @@ class Parser {
   ParserResult<ImportDecl> parseDeclImport(ParseDeclOptions Flags,
                                            DeclAttributes &Attributes);
   ParserStatus parseInheritance(SmallVectorImpl<TypeLoc> &Inherited,
-                                SourceLoc *classRequirementLoc);
+                                bool allowClassRequirement);
   ParserStatus parseDeclItem(bool &PreviousHadSemi,
                              Parser::ParseDeclOptions Options,
                              llvm::function_ref<void(Decl*)> handler);

lib/AST/ASTPrinter.cpp

@@ -594,11 +594,9 @@ class PrintAST : public ASTVisitor<PrintAST> {
   void printInherited(const Decl *decl,
                       ArrayRef<TypeLoc> inherited,
                       ArrayRef<ProtocolDecl *> protos,
-                      Type superclass = {},
-                      bool explicitClass = false);
+                      Type superclass = {});
 
-  void printInherited(const NominalTypeDecl *decl,
-                      bool explicitClass = false);
+  void printInherited(const NominalTypeDecl *decl);
   void printInherited(const EnumDecl *D);
   void printInherited(const ExtensionDecl *decl);
   void printInherited(const GenericTypeParamDecl *D);
@@ -1635,9 +1633,8 @@ void PrintAST::printNominalDeclGenericRequirements(NominalTypeDecl *decl) {
 void PrintAST::printInherited(const Decl *decl,
                               ArrayRef<TypeLoc> inherited,
                               ArrayRef<ProtocolDecl *> protos,
-                              Type superclass,
-                              bool explicitClass) {
-  if (inherited.empty() && superclass.isNull() && !explicitClass) {
+                              Type superclass) {
+  if (inherited.empty() && superclass.isNull()) {
     if (protos.empty())
       return;
   }
@@ -1646,10 +1643,7 @@ void PrintAST::printInherited(const Decl *decl,
     bool PrintedColon = false;
     bool PrintedInherited = false;
 
-    if (explicitClass) {
-      Printer << " : " << tok::kw_class;
-      PrintedInherited = true;
-    } else if (superclass) {
+    if (superclass) {
       bool ShouldPrintSuper = true;
       if (auto NTD = superclass->getAnyNominal()) {
         ShouldPrintSuper = shouldPrint(NTD);
@@ -1701,9 +1695,6 @@ void PrintAST::printInherited(const Decl *decl,
 
     Printer << " : ";
 
-    if (explicitClass)
-      Printer << " " << tok::kw_class << ", ";
-
     interleave(TypesToPrint, [&](TypeLoc TL) {
       printTypeLoc(TL);
     }, [&]() {
@@ -1712,9 +1703,8 @@ void PrintAST::printInherited(const Decl *decl,
   }
 }
 
-void PrintAST::printInherited(const NominalTypeDecl *decl,
-                              bool explicitClass) {
-  printInherited(decl, decl->getInherited(), { }, nullptr, explicitClass);
+void PrintAST::printInherited(const NominalTypeDecl *decl) {
+  printInherited(decl, decl->getInherited(), { }, nullptr);
 }
 
 void PrintAST::printInherited(const EnumDecl *decl) {
@@ -2139,23 +2129,7 @@ void PrintAST::visitProtocolDecl(ProtocolDecl *decl) {
         Printer.printName(decl->getName());
       });
 
-    // Figure out whether we need an explicit 'class' in the inheritance.
-    bool explicitClass = false;
-    if (decl->requiresClass() && !decl->isObjC()) {
-      bool inheritsRequiresClass = false;
-      for (auto proto : decl->getLocalProtocols(
-                          ConformanceLookupKind::OnlyExplicit)) {
-        if (proto->requiresClass()) {
-          inheritsRequiresClass = true;
-          break;
-        }
-      }
-
-      if (!inheritsRequiresClass)
-        explicitClass = true;
-    }
-
-    printInherited(decl, explicitClass);
+    printInherited(decl);
 
     // The trailing where clause is a syntactic thing, which isn't serialized
     // (etc.) and thus isn't available for printing things out of

lib/Parse/ParseDecl.cpp

@@ -2651,13 +2651,11 @@ ParserResult<ImportDecl> Parser::parseDeclImport(ParseDeclOptions Flags,
 ///     type-identifier
 /// \endverbatim
 ParserStatus Parser::parseInheritance(SmallVectorImpl<TypeLoc> &Inherited,
-                                      SourceLoc *classRequirementLoc) {
+                                      bool allowClassRequirement) {
   Scope S(this, ScopeKind::InheritanceClause);
   consumeToken(tok::colon);
 
-  // Clear out the class requirement location.
-  if (classRequirementLoc)
-    *classRequirementLoc = SourceLoc();
+  SourceLoc classRequirementLoc;
 
   ParserStatus Status;
   SourceLoc prevComma;
@@ -2666,17 +2664,17 @@ ParserStatus Parser::parseInheritance(SmallVectorImpl<TypeLoc> &Inherited,
     if (Tok.is(tok::kw_class)) {
       // If we aren't allowed to have a class requirement here, complain.
       auto classLoc = consumeToken();
-      if (!classRequirementLoc) {
+      if (!allowClassRequirement) {
         SourceLoc endLoc = Tok.is(tok::comma) ? Tok.getLoc() : classLoc;
         diagnose(classLoc, diag::invalid_class_requirement)
           .fixItRemove(SourceRange(classLoc, endLoc));
         continue;
       }
 
       // If we already saw a class requirement, complain.
-      if (classRequirementLoc->isValid()) {
+      if (classRequirementLoc.isValid()) {
         diagnose(classLoc, diag::redundant_class_requirement)
-          .highlight(*classRequirementLoc)
+          .highlight(classRequirementLoc)
           .fixItRemove(SourceRange(prevComma, classLoc));
         continue;
       }
@@ -2690,7 +2688,12 @@ ParserStatus Parser::parseInheritance(SmallVectorImpl<TypeLoc> &Inherited,
       }
 
       // Record the location of the 'class' keyword.
-      *classRequirementLoc = classLoc;
+      classRequirementLoc = classLoc;
+
+      // Add 'AnyObject' to the inherited list.
+      Inherited.push_back(
+        new (Context) SimpleIdentTypeRepr(classLoc,
+                                          Context.getIdentifier("AnyObject")));
       continue;
     }
 
@@ -2954,7 +2957,7 @@ Parser::parseDeclExtension(ParseDeclOptions Flags, DeclAttributes &Attributes) {
   // Parse optional inheritance clause.
   SmallVector<TypeLoc, 2> Inherited;
   if (Tok.is(tok::colon))
-    status |= parseInheritance(Inherited, /*classRequirementLoc=*/nullptr);
+    status |= parseInheritance(Inherited, /*allowClassRequirement=*/false);
 
   // Parse the optional where-clause.
   TrailingWhereClause *trailingWhereClause = nullptr;
@@ -3293,7 +3296,7 @@ ParserResult<TypeDecl> Parser::parseDeclAssociatedType(Parser::ParseDeclOptions
   // FIXME: Allow class requirements here.
   SmallVector<TypeLoc, 2> Inherited;
   if (Tok.is(tok::colon))
-    Status |= parseInheritance(Inherited, /*classRequirementLoc=*/nullptr);
+    Status |= parseInheritance(Inherited, /*allowClassRequirement=*/false);
 
   ParserResult<TypeRepr> UnderlyingTy;
   if (Tok.is(tok::equal)) {
@@ -5033,7 +5036,7 @@ ParserResult<EnumDecl> Parser::parseDeclEnum(ParseDeclOptions Flags,
   // Parse optional inheritance clause within the context of the enum.
   if (Tok.is(tok::colon)) {
     SmallVector<TypeLoc, 2> Inherited;
-    Status |= parseInheritance(Inherited, /*classRequirementLoc=*/nullptr);
+    Status |= parseInheritance(Inherited, /*allowClassRequirement=*/false);
     ED->setInherited(Context.AllocateCopy(Inherited));
   }
 
@@ -5293,7 +5296,7 @@ ParserResult<StructDecl> Parser::parseDeclStruct(ParseDeclOptions Flags,
   // Parse optional inheritance clause within the context of the struct.
   if (Tok.is(tok::colon)) {
     SmallVector<TypeLoc, 2> Inherited;
-    Status |= parseInheritance(Inherited, /*classRequirementLoc=*/nullptr);
+    Status |= parseInheritance(Inherited, /*allowClassRequirement=*/false);
     SD->setInherited(Context.AllocateCopy(Inherited));
   }
 
@@ -5378,7 +5381,7 @@ ParserResult<ClassDecl> Parser::parseDeclClass(SourceLoc ClassLoc,
   // Parse optional inheritance clause within the context of the class.
   if (Tok.is(tok::colon)) {
     SmallVector<TypeLoc, 2> Inherited;
-    Status |= parseInheritance(Inherited, /*classRequirementLoc=*/nullptr);
+    Status |= parseInheritance(Inherited, /*allowClassRequirement=*/false);
     CD->setInherited(Context.AllocateCopy(Inherited));
   }
 
@@ -5462,11 +5465,11 @@ parseDeclProtocol(ParseDeclOptions Flags, DeclAttributes &Attributes) {
 
   // Parse optional inheritance clause.
   SmallVector<TypeLoc, 4> InheritedProtocols;
-  SourceLoc classRequirementLoc;
   SourceLoc colonLoc;
   if (Tok.is(tok::colon)) {
     colonLoc = Tok.getLoc();
-    Status |= parseInheritance(InheritedProtocols, &classRequirementLoc);
+    Status |= parseInheritance(InheritedProtocols,
+                               /*allowClassRequirement=*/true);
   }
 
   TrailingWhereClause *TrailingWhere = nullptr;
@@ -5483,10 +5486,6 @@ parseDeclProtocol(ParseDeclOptions Flags, DeclAttributes &Attributes) {
                    Context.AllocateCopy(InheritedProtocols), TrailingWhere);
   // No need to setLocalDiscriminator: protocols can't appear in local contexts.
 
-  // If there was a 'class' requirement, mark this as a class-bounded protocol.
-  if (classRequirementLoc.isValid())
-    Proto->setClassBounded(classRequirementLoc);
-
   Proto->getAttrs() = Attributes;
 
   ContextChange CC(*this, Proto);

test/IDE/print_ast_tc_decls.swift

@@ -486,7 +486,7 @@ protocol d0130_TestProtocol {
 }
 
 protocol d0150_TestClassProtocol : class {}
-// PASS_COMMON-LABEL: {{^}}protocol d0150_TestClassProtocol : class {{{$}}
+// PASS_COMMON-LABEL: {{^}}protocol d0150_TestClassProtocol : AnyObject where Self : AnyObject {{{$}}
 
 @objc protocol d0151_TestClassProtocol {}
 // PASS_COMMON-LABEL: {{^}}@objc protocol d0151_TestClassProtocol {{{$}}

test/IRGen/existentials_objc.sil

@@ -7,8 +7,11 @@
 
 sil_stage canonical
 
+import Builtin
 import gizmo
 
+typealias AnyObject = Builtin.AnyObject
+
 // rdar://16621578
 
 sil @init_opaque_existential : $@convention(thin) <T where T : Gizmo> (@owned T) -> @out Any {

test/IRGen/fixlifetime.sil

@@ -28,8 +28,12 @@
 // CHECK-native:  call void @__swift_fixLifetime(%swift.refcounted*
 // CHECK-native:  call void bitcast (void (%swift.refcounted*)* @__swift_fixLifetime to void (%T11fixlifetime1CC**)*)(%T11fixlifetime1CC**
 
+import Builtin
+
 sil_stage canonical
 
+typealias AnyObject = Builtin.AnyObject
+
 class C {}
 sil_vtable C {}
 protocol P : class {}

test/IRGen/unowned.sil

@@ -7,8 +7,12 @@
 // CHECK: [[OPAQUE:%swift.opaque]] = type opaque
 // CHECK: [[A:%T7unowned1AV]] = type <{ %swift.unowned }>
 
+import Builtin
+
 class C {}
 sil_vtable C {}
+
+typealias AnyObject = Builtin.AnyObject
 protocol P : class {
   func explode()
 }

test/IRGen/unowned_objc.sil

@@ -3,6 +3,8 @@
 // REQUIRES: CPU=x86_64
 // XFAIL: linux
 
+import Builtin
+
 //   These types end up in a completely different order with interop disabled.
 // CHECK: [[TYPE:%swift.type]] = type
 // CHECK: [[OPAQUE:%swift.opaque]] = type opaque
@@ -12,6 +14,7 @@
 
 class C {}
 sil_vtable C {}
+typealias AnyObject = Builtin.AnyObject
 protocol P : class {
   func explode()
 }

test/SIL/clone_init_existential.sil

@@ -7,6 +7,8 @@ sil_stage canonical
 
 import Builtin
 
+typealias AnyObject = Builtin.AnyObject
+
 protocol ClassProto1 : class {
 }
 

test/SIL/ownership-verifier/objc_use_verifier.sil

@@ -2,7 +2,7 @@
 // REQUIRES: asserts
 // REQUIRES: objc_interop
 
-@objc protocol NSBurrito : class {}
+@objc protocol NSBurrito {}
 
 class Protocol : NSBurrito {}
 

test/SIL/ownership-verifier/opaque_use_verifier.sil

@@ -58,7 +58,7 @@ bb0(%0 : @guaranteed $T):
   return %4 : $T
 }
 
-public protocol AnyObject : class {}
+typealias AnyObject = Builtin.AnyObject
 
 sil @takeType : $@convention(thin) (@thick AnyObject.Type) -> () {
 bb0(%0 : @trivial $@thick AnyObject.Type):

test/SIL/ownership-verifier/use_verifier.sil

@@ -15,7 +15,7 @@ import Builtin
 
 sil @allocate_object : $@convention(thin) () -> @owned Builtin.NativeObject
 
-public protocol AnyObject : class {}
+typealias AnyObject = Builtin.AnyObject
 
 public protocol Error {}
 

test/SILGen/class_bound_protocols.swift

@@ -7,6 +7,8 @@ enum Optional<T> {
 
 precedencegroup AssignmentPrecedence {}
 
+typealias AnyObject = Builtin.AnyObject
+
 // -- Class-bound archetypes and existentials are *not* address-only and can
 //    be manipulated using normal reference type value semantics.
 

test/SILGen/objc_imported_generic.swift

@@ -89,9 +89,9 @@ public func genericBlockBridging<T: Ansible>(x: GenericClass<T>) {
 }
 
 // CHECK-LABEL: sil @_T021objc_imported_generic0C13BlockBridging{{[_0-9a-zA-Z]*}}F
-// CHECK:         [[BLOCK_TO_FUNC:%.*]] = function_ref @_T0xxIyBya_xxIxxo_RlzC21objc_imported_generic7AnsibleRzlTR
+// CHECK:         [[BLOCK_TO_FUNC:%.*]] = function_ref @_T0xxIyBya_xxIxxo_21objc_imported_generic7AnsibleRzlTR
 // CHECK:         partial_apply [[BLOCK_TO_FUNC]]<T>
-// CHECK:         [[FUNC_TO_BLOCK:%.*]] = function_ref @_T0xxIxxo_xxIyBya_RlzC21objc_imported_generic7AnsibleRzlTR
+// CHECK:         [[FUNC_TO_BLOCK:%.*]] = function_ref @_T0xxIxxo_xxIyBya_21objc_imported_generic7AnsibleRzlTR
 // CHECK:         init_block_storage_header {{.*}} invoke [[FUNC_TO_BLOCK]]<T>
 
 // CHECK-LABEL: sil @_T021objc_imported_generic20arraysOfGenericParam{{[_0-9a-zA-Z]*}}F

test/SILOptimizer/address_projection.sil

@@ -5,6 +5,7 @@ import Builtin
 sil_stage canonical
 // CHECK: sil_stage lowered
 
+typealias AnyObject = Builtin.AnyObject
 typealias Int = Builtin.Int64
 
 // CHECK-LABEL: sil hidden @f010_addrlower_identity : $@convention(thin) <T> (@in T) -> @out T {

test/SILOptimizer/rcidentity.sil

@@ -6,6 +6,8 @@ import Builtin
 // NonTest Utilities //
 ///////////////////////
 
+typealias AnyObject = Builtin.AnyObject
+
 protocol FakeAnyObject : class {}
 
 class C : FakeAnyObject {

test/SourceKit/CursorInfo/cursor_info.swift

@@ -599,7 +599,7 @@ func hasLocalizationKey2() {}
 // FIXME: ref.class - rdar://problem/25014968
 
 // RUN: %sourcekitd-test -req=cursor -pos=150:10 %s -- -F %S/../Inputs/libIDE-mock-sdk -I %t.tmp %mcp_opt %s | %FileCheck %s -check-prefix=CHECK66
-// CHECK66: <decl.protocol><syntaxtype.keyword>protocol</syntaxtype.keyword> <decl.name>P2</decl.name> :  <syntaxtype.keyword>class</syntaxtype.keyword>, <ref.protocol usr="s:11cursor_info2P1P">P1</ref.protocol></decl.protocol>
+// CHECK66: <decl.protocol><syntaxtype.keyword>protocol</syntaxtype.keyword> <decl.name>P2</decl.name> : <ref.typealias usr="s:s9AnyObjecta">AnyObject</ref.typealias>, <ref.protocol usr="s:11cursor_info2P1P">P1</ref.protocol> <syntaxtype.keyword>where</syntaxtype.keyword> <decl.generic_type_requirement><ref.generic_type_param usr="s:11cursor_info2P2P4Selfxmfp">Self</ref.generic_type_param> : AnyObject</decl.generic_type_requirement></decl.protocol>
 
 // RUN: %sourcekitd-test -req=cursor -pos=114:18 %s -- -F %S/../Inputs/libIDE-mock-sdk -I %t.tmp %mcp_opt %s | %FileCheck %s -check-prefix=CHECK67
 // CHECK67: source.lang.swift.decl.associatedtype (114:18-114:19)

test/decl/protocol/req/class.swift

@@ -5,5 +5,7 @@ protocol P1 : class { }
 protocol P2 : class, class { } // expected-error{{redundant 'class' requirement}}{{20-27=}}
 
 protocol P3 : P2, class { } // expected-error{{'class' must come first in the requirement list}}{{15-15=class, }}{{17-24=}}
+// expected-warning@-1 {{redundant layout constraint 'Self' : 'AnyObject'}}
+// expected-note@-2 {{layout constraint constraint 'Self' : 'AnyObject' implied here}}
 
 struct X : class { } // expected-error{{'class' requirement only applies to protocols}} {{12-18=}}