Sema: The primary associated type list references existing associated types instead of declaring new ones

Author: slavapestov

include/swift/AST/Decl.h

@@ -506,11 +506,6 @@ class alignas(1 << DeclAlignInBits) Decl : public ASTAllocated<Decl> {
     IsOpaqueType : 1
   );
 
-  SWIFT_INLINE_BITFIELD_FULL(AssociatedTypeDecl, AbstractTypeParamDecl, 1,
-    /// Whether this is a primary associated type.
-    IsPrimary : 1
-  );
-
   SWIFT_INLINE_BITFIELD_EMPTY(GenericTypeDecl, TypeDecl);
 
   SWIFT_INLINE_BITFIELD(TypeAliasDecl, GenericTypeDecl, 1+1,
@@ -3272,14 +3267,6 @@ class AssociatedTypeDecl : public AbstractTypeParamDecl {
                      LazyMemberLoader *definitionResolver,
                      uint64_t resolverData);
 
-  bool isPrimary() const {
-    return Bits.AssociatedTypeDecl.IsPrimary;
-  }
-
-  void setPrimary() {
-    Bits.AssociatedTypeDecl.IsPrimary = true;
-  }
-
   /// Get the protocol in which this associated type is declared.
   ProtocolDecl *getProtocol() const {
     return cast<ProtocolDecl>(getDeclContext());
@@ -4363,6 +4350,8 @@ enum class KnownDerivableProtocolKind : uint8_t {
   DistributedActorSystem,
 };
 
+using PrimaryAssociatedTypeName = std::pair<Identifier, SourceLoc>;
+
 /// ProtocolDecl - A declaration of a protocol, for example:
 ///
 ///   protocol Drawable {
@@ -4379,6 +4368,7 @@ enum class KnownDerivableProtocolKind : uint8_t {
 class ProtocolDecl final : public NominalTypeDecl {
   SourceLoc ProtocolLoc;
 
+  ArrayRef<PrimaryAssociatedTypeName> PrimaryAssociatedTypeNames;
   ArrayRef<ProtocolDecl *> InheritedProtocols;
   ArrayRef<AssociatedTypeDecl *> AssociatedTypes;
 
@@ -4460,7 +4450,9 @@ class ProtocolDecl final : public NominalTypeDecl {
 
 public:
   ProtocolDecl(DeclContext *DC, SourceLoc ProtocolLoc, SourceLoc NameLoc,
-               Identifier Name, ArrayRef<InheritedEntry> Inherited,
+               Identifier Name,
+               ArrayRef<PrimaryAssociatedTypeName> PrimaryAssociatedTypeNames,
+               ArrayRef<InheritedEntry> Inherited,
                TrailingWhereClause *TrailingWhere);
 
   using Decl::getASTContext;
@@ -4486,6 +4478,13 @@ class ProtocolDecl final : public NominalTypeDecl {
   /// a protocol having nested types (ObjC protocols).
   ArrayRef<AssociatedTypeDecl *> getAssociatedTypeMembers() const;
 
+  /// Returns the list of primary associated type names. These are the associated
+  /// types that is parametrized with same-type requirements in a
+  /// parametrized protocol type of the form SomeProtocol<Arg1, Arg2...>.
+  ArrayRef<PrimaryAssociatedTypeName> getPrimaryAssociatedTypeNames() const {
+    return PrimaryAssociatedTypeNames;
+  }
+
   /// Returns the list of primary associated types. These are the associated
   /// types that is parametrized with same-type requirements in a
   /// parametrized protocol type of the form SomeProtocol<Arg1, Arg2...>.

include/swift/AST/DiagnosticsSema.def

@@ -3770,6 +3770,11 @@ ERROR(not_a_generic_definition,none,
       "cannot specialize a non-generic definition", ())
 ERROR(not_a_generic_type,none,
       "cannot specialize non-generic type %0", (Type))
+ERROR(protocol_declares_unknown_primary_assoc_type,none,
+      "an associated type named %0 must be declared in the protocol %1 or a protocol it inherits",
+      (Identifier, Type))
+ERROR(protocol_declares_duplicate_primary_assoc_type,none,
+      "duplicate primary associated type name %0", (Identifier))
 ERROR(parameterized_protocol_not_supported,none,
       "protocol type with generic arguments can only be used as a generic constraint", ())
 ERROR(protocol_does_not_have_primary_assoc_type,none,

include/swift/Parse/Parser.h

@@ -1213,9 +1213,9 @@ class Parser {
   parseAbstractFunctionBodyDelayed(AbstractFunctionDecl *AFD);
 
   ParserStatus parsePrimaryAssociatedTypes(
-      SmallVectorImpl<AssociatedTypeDecl *> &AssocTypes);
+      SmallVectorImpl<PrimaryAssociatedTypeName> &AssocTypeNames);
   ParserStatus parsePrimaryAssociatedTypeList(
-      SmallVectorImpl<AssociatedTypeDecl *> &AssocTypes);
+      SmallVectorImpl<PrimaryAssociatedTypeName> &AssocTypeNames);
   ParserResult<ProtocolDecl> parseDeclProtocol(ParseDeclOptions Flags,
                                                DeclAttributes &Attributes);
 

lib/AST/ASTPrinter.cpp

@@ -1381,8 +1381,7 @@ struct RequirementPrintLocation {
 /// function does: asking "where should this requirement be printed?" and then
 /// callers check if the location is the ATD.
 static RequirementPrintLocation
-bestRequirementPrintLocation(ProtocolDecl *proto, const Requirement &req,
-                             PrintOptions opts, bool inheritanceClause) {
+bestRequirementPrintLocation(ProtocolDecl *proto, const Requirement &req) {
   auto protoSelf = proto->getProtocolSelfType();
   // Returns the most relevant decl within proto connected to outerType (or null
   // if one doesn't exist), and whether the type is an "direct use",
@@ -1415,16 +1414,6 @@ bestRequirementPrintLocation(ProtocolDecl *proto, const Requirement &req,
     // desired.
     auto directUse = foundType && outerType->isEqual(foundType);
 
-    // Prefer to attach requirements to associated type declarations,
-    // unless the associated type is a primary associated type and
-    // we're printing primary associated types using the new syntax.
-    if (!directUse &&
-        relevantDecl &&
-        opts.PrintPrimaryAssociatedTypes &&
-        isa<AssociatedTypeDecl>(relevantDecl) &&
-        cast<AssociatedTypeDecl>(relevantDecl)->isPrimary())
-      relevantDecl = proto;
-
     return std::make_pair(relevantDecl, directUse);
   };
 
@@ -1495,8 +1484,7 @@ void PrintAST::printInheritedFromRequirementSignature(ProtocolDecl *proto,
           return false;
         }
 
-        auto location = bestRequirementPrintLocation(proto, req, Options,
-                                                     /*inheritanceClause=*/true);
+        auto location = bestRequirementPrintLocation(proto, req);
         return location.AttachedTo == attachingTo && !location.InWhereClause;
       });
 }
@@ -1511,8 +1499,7 @@ void PrintAST::printWhereClauseFromRequirementSignature(ProtocolDecl *proto,
                             proto->getRequirementSignature().getRequirements()),
       flags,
       [&](const Requirement &req) {
-        auto location = bestRequirementPrintLocation(proto, req, Options,
-                                                     /*inheritanceClause=*/false);
+        auto location = bestRequirementPrintLocation(proto, req);
         return location.AttachedTo == attachingTo && location.InWhereClause;
       });
 }
@@ -3557,14 +3544,6 @@ void PrintAST::printPrimaryAssociatedTypes(ProtocolDecl *decl) {
                                       assocType);
         Printer.printName(assocType->getName(),
                           PrintNameContext::GenericParameter);
-
-        printInheritedFromRequirementSignature(decl, assocType);
-
-        if (assocType->hasDefaultDefinitionType()) {
-          Printer << " = ";
-          assocType->getDefaultDefinitionType().print(Printer, Options);
-        }
-
         Printer.printStructurePost(PrintStructureKind::GenericParameter,
                                    assocType);
       },
@@ -5092,14 +5071,6 @@ bool Decl::shouldPrintInContext(const PrintOptions &PO) const {
     return PO.PrintIfConfig;
   }
 
-  if (auto *ATD = dyn_cast<AssociatedTypeDecl>(this)) {
-    // If PO.PrintPrimaryAssociatedTypes is on, primary associated
-    // types are printed as part of the protocol declaration itself,
-    // so skip them here.
-    if (ATD->isPrimary() && PO.PrintPrimaryAssociatedTypes)
-      return false;
-  }
-
   // Print everything else.
   return true;
 }

lib/AST/Decl.cpp

@@ -4557,9 +4557,7 @@ AssociatedTypeDecl::AssociatedTypeDecl(DeclContext *dc, SourceLoc keywordLoc,
                                        TrailingWhereClause *trailingWhere)
     : AbstractTypeParamDecl(DeclKind::AssociatedType, dc, name, nameLoc),
       KeywordLoc(keywordLoc), DefaultDefinition(defaultDefinition),
-      TrailingWhere(trailingWhere) {
-  Bits.AssociatedTypeDecl.IsPrimary = 0;
-}
+      TrailingWhere(trailingWhere) {}
 
 AssociatedTypeDecl::AssociatedTypeDecl(DeclContext *dc, SourceLoc keywordLoc,
                                        Identifier name, SourceLoc nameLoc,
@@ -5305,11 +5303,13 @@ bool EnumDecl::hasCircularRawValue() const {
 
 ProtocolDecl::ProtocolDecl(DeclContext *DC, SourceLoc ProtocolLoc,
                            SourceLoc NameLoc, Identifier Name,
+                           ArrayRef<PrimaryAssociatedTypeName> PrimaryAssociatedTypeNames,
                            ArrayRef<InheritedEntry> Inherited,
                            TrailingWhereClause *TrailingWhere)
     : NominalTypeDecl(DeclKind::Protocol, DC, Name, NameLoc, Inherited,
                       nullptr),
-      ProtocolLoc(ProtocolLoc) {
+      ProtocolLoc(ProtocolLoc),
+      PrimaryAssociatedTypeNames(PrimaryAssociatedTypeNames) {
   Bits.ProtocolDecl.RequiresClassValid = false;
   Bits.ProtocolDecl.RequiresClass = false;
   Bits.ProtocolDecl.ExistentialConformsToSelfValid = false;

lib/ClangImporter/ImportDecl.cpp

@@ -5677,7 +5677,8 @@ namespace {
       auto result = Impl.createDeclWithClangNode<ProtocolDecl>(
           decl, AccessLevel::Public, dc,
           Impl.importSourceLoc(decl->getBeginLoc()),
-          Impl.importSourceLoc(decl->getLocation()), name, None,
+          Impl.importSourceLoc(decl->getLocation()), name,
+          ArrayRef<PrimaryAssociatedTypeName>(), None,
           /*TrailingWhere=*/nullptr);
 
       addObjCAttribute(result, Impl.importIdentifier(decl->getIdentifier()));

lib/Parse/ParseDecl.cpp

@@ -7977,13 +7977,13 @@ ParserResult<ClassDecl> Parser::parseDeclClass(ParseDeclOptions Flags,
 }
 
 ParserStatus Parser::parsePrimaryAssociatedTypes(
-    SmallVectorImpl<AssociatedTypeDecl *> &AssocTypes) {
+    SmallVectorImpl<PrimaryAssociatedTypeName> &AssocTypeNames) {
   SyntaxParsingContext GPSContext(SyntaxContext,
                                   SyntaxKind::PrimaryAssociatedTypeClause);
 
   SourceLoc LAngleLoc = consumeStartingLess();
 
-  auto Result = parsePrimaryAssociatedTypeList(AssocTypes);
+  auto Result = parsePrimaryAssociatedTypeList(AssocTypeNames);
 
   // Parse the closing '>'.
   SourceLoc RAngleLoc;
@@ -8001,7 +8001,7 @@ ParserStatus Parser::parsePrimaryAssociatedTypes(
 }
 
 ParserStatus Parser::parsePrimaryAssociatedTypeList(
-    SmallVectorImpl<AssociatedTypeDecl *> &AssocTypes) {
+    SmallVectorImpl<PrimaryAssociatedTypeName> &AssocTypeNames) {
   ParserStatus Result;
   SyntaxParsingContext PATContext(SyntaxContext,
                                   SyntaxKind::PrimaryAssociatedTypeList);
@@ -8011,16 +8011,6 @@ ParserStatus Parser::parsePrimaryAssociatedTypeList(
     SyntaxParsingContext ATContext(SyntaxContext,
                                    SyntaxKind::PrimaryAssociatedType);
 
-    // Note that we're parsing a declaration.
-    StructureMarkerRAII ParsingDecl(*this, Tok.getLoc(),
-                                    StructureMarkerKind::Declaration);
-
-    // Parse attributes.
-    DeclAttributes Attrs;
-    if (Tok.hasComment())
-      Attrs.add(new (Context) RawDocCommentAttr(Tok.getCommentRange()));
-    parseDeclAttributeList(Attrs);
-
     // Parse the name of the parameter.
     Identifier Name;
     SourceLoc NameLoc;
@@ -8030,54 +8020,7 @@ ParserStatus Parser::parsePrimaryAssociatedTypeList(
       break;
     }
 
-    // Parse the ':' followed by a type.
-    SmallVector<InheritedEntry, 1> Inherited;
-    if (Tok.is(tok::colon)) {
-      (void)consumeToken();
-      ParserResult<TypeRepr> Ty;
-
-      if (Tok.isAny(tok::identifier, tok::code_complete, tok::kw_protocol,
-                    tok::kw_Any)) {
-        Ty = parseType();
-      } else if (Tok.is(tok::kw_class)) {
-        diagnose(Tok, diag::unexpected_class_constraint);
-        diagnose(Tok, diag::suggest_anyobject)
-        .fixItReplace(Tok.getLoc(), "AnyObject");
-        consumeToken();
-        Result.setIsParseError();
-      } else {
-        diagnose(Tok, diag::expected_generics_type_restriction, Name);
-        Result.setIsParseError();
-      }
-
-      if (Ty.hasCodeCompletion())
-        return makeParserCodeCompletionStatus();
-
-      if (Ty.isNonNull())
-        Inherited.push_back({Ty.get()});
-    }
-
-    ParserResult<TypeRepr> UnderlyingTy;
-    if (Tok.is(tok::equal)) {
-      SyntaxParsingContext InitContext(SyntaxContext,
-                                       SyntaxKind::TypeInitializerClause);
-      consumeToken(tok::equal);
-      UnderlyingTy = parseType(diag::expected_type_in_associatedtype);
-      Result |= UnderlyingTy;
-      if (UnderlyingTy.isNull())
-        return Result;
-    }
-
-    auto *AssocType = new (Context)
-        AssociatedTypeDecl(CurDeclContext, NameLoc, Name, NameLoc,
-                           UnderlyingTy.getPtrOrNull(),
-                           /*trailingWhere=*/nullptr);
-    AssocType->getAttrs() = Attrs;
-    if (!Inherited.empty())
-      AssocType->setInherited(Context.AllocateCopy(Inherited));
-    AssocType->setPrimary();
-
-    AssocTypes.push_back(AssocType);
+    AssocTypeNames.emplace_back(Name, NameLoc);
 
     // Parse the comma, if the list continues.
     HasNextParam = consumeIf(tok::comma);
@@ -8097,13 +8040,7 @@ ParserStatus Parser::parsePrimaryAssociatedTypeList(
 ///     inheritance? 
 ///
 ///   primary-associated-type-list:
-///     '<' primary-associated-type+ '>'
-///
-///   primary-associated-type:
-///     identifier inheritance? default-associated-type
-///
-///   default-associated-type:
-///     '=' type
+///     '<' identifier+ '>'
 ///
 ///   protocol-member:
 ///      decl-func
@@ -8124,11 +8061,11 @@ parseDeclProtocol(ParseDeclOptions Flags, DeclAttributes &Attributes) {
   if (Status.isErrorOrHasCompletion())
     return Status;
 
-  SmallVector<AssociatedTypeDecl *, 2> PrimaryAssociatedTypes;
+  SmallVector<PrimaryAssociatedTypeName, 2> PrimaryAssociatedTypeNames;
 
   if (Context.LangOpts.EnableParameterizedProtocolTypes) {
     if (startsWithLess(Tok)) {
-      Status |= parsePrimaryAssociatedTypes(PrimaryAssociatedTypes);
+      Status |= parsePrimaryAssociatedTypes(PrimaryAssociatedTypeNames);
     }
   } else {
     // Protocols don't support generic parameters, but people often want them and
@@ -8167,6 +8104,7 @@ parseDeclProtocol(ParseDeclOptions Flags, DeclAttributes &Attributes) {
 
   ProtocolDecl *Proto = new (Context)
       ProtocolDecl(CurDeclContext, ProtocolLoc, NameLoc, ProtocolName,
+                   Context.AllocateCopy(PrimaryAssociatedTypeNames),
                    Context.AllocateCopy(InheritedProtocols), TrailingWhere);
   // No need to setLocalDiscriminator: protocols can't appear in local contexts.
 
@@ -8176,12 +8114,6 @@ parseDeclProtocol(ParseDeclOptions Flags, DeclAttributes &Attributes) {
 
   ContextChange CC(*this, Proto);
 
-  // Re-parent the primary associated type declarations into the protocol.
-  for (auto *AssocType : PrimaryAssociatedTypes) {
-    AssocType->setDeclContext(Proto);
-    Proto->addMember(AssocType);
-  }
-
   // Parse the body.
   {
     SyntaxParsingContext BlockContext(SyntaxContext, SyntaxKind::MemberDeclBlock);