[5.9][Macros] Allow extension macros to suppress conformances that are stated in the original source.

include/swift/AST/Decl.h

@@ -8595,6 +8595,15 @@ class MacroDecl : public GenericContext, public ValueDecl {
   void getIntroducedNames(MacroRole role, ValueDecl *attachedTo,
                           SmallVectorImpl<DeclName> &names) const;
 
+  /// Populate the \c conformances vector with the protocols that
+  /// this macro generates conformances to.
+  ///
+  /// Only extension macros can add conformances; no results will
+  /// be added if this macro does not contain an extension role.
+  void getIntroducedConformances(
+      NominalTypeDecl *attachedTo,
+      SmallVectorImpl<ProtocolDecl *> &conformances) const;
+
   /// Returns a DeclName that represents arbitrary names.
   static DeclName getArbitraryName() {
     return DeclName();

include/swift/AST/DeclContext.h

@@ -154,6 +154,10 @@ enum class ConformanceEntryKind : unsigned {
 
   /// Implied by an explicitly-specified conformance.
   Implied,
+
+  /// The conformance is generated by a macro that has not been
+  /// expanded yet.
+  PreMacroExpansion,
 };
 
 /// Describes the kind of conformance lookup desired.
@@ -167,6 +171,9 @@ enum class ConformanceLookupKind : unsigned {
   /// All conformances except structurally-derived conformances, of which
   /// Sendable is the only one.
   NonStructural,
+  /// Exclude conformances added by a macro that has not been expanded
+  /// yet.
+  ExcludeUnexpandedMacros,
 };
 
 /// Describes a diagnostic for a conflict between two protocol

include/swift/AST/DiagnosticsSema.def

@@ -2726,7 +2726,8 @@ NOTE(declared_protocol_conformance_here,none,
      "%select{%0 inherits conformance to protocol %2 from superclass|"
      "%0 declares conformance to protocol %2|"
      "%0 implicitly conforms to protocol %2 (via conformance to %3)|"
-     "%0 implicitly conforms to protocol %2}1 here",
+     "%0 implicitly conforms to protocol %2 |"
+     "conformance to %2 generated by macro }1 here",
      (Type, unsigned, Identifier, Identifier))
 
 ERROR(witness_unavailable,none,
@@ -7151,6 +7152,9 @@ ERROR(global_arbitrary_name,none,
 ERROR(local_extension_macro,none,
       "local type cannot have attached extension macro",
       ())
+ERROR(extension_macro_invalid_conformance,none,
+      "invalid protocol conformance %0 in extension macro",
+      (Type))
 
 ERROR(macro_resolve_circular_reference, none,
       "circular reference resolving %select{freestanding|attached}0 macro %1",

include/swift/AST/ProtocolConformance.h

@@ -440,7 +440,7 @@ class NormalProtocolConformance : public RootProtocolConformance,
   ///
   /// This should never be Inherited: that is handled by
   /// InheritedProtocolConformance.
-  llvm::PointerIntPair<NormalProtocolConformance *, 2, ConformanceEntryKind>
+  llvm::PointerIntPair<NormalProtocolConformance *, 3, ConformanceEntryKind>
       SourceKindAndImplyingConformance = {nullptr,
                                           ConformanceEntryKind::Explicit};
 

include/swift/AST/TypeCheckRequests.h

@@ -3337,6 +3337,25 @@ class ResolveMacroRequest
   void noteCycleStep(DiagnosticEngine &diags) const;
 };
 
+/// Returns the resolved constraint types that an extension macro
+/// adds conformances to.
+class ResolveExtensionMacroConformances
+    : public SimpleRequest<ResolveExtensionMacroConformances,
+                           ArrayRef<Type>(const MacroRoleAttr *, const Decl *),
+                           RequestFlags::Cached> {
+public:
+  using SimpleRequest::SimpleRequest;
+
+private:
+  friend SimpleRequest;
+
+  ArrayRef<Type> evaluate(Evaluator &evaluator,
+                          const MacroRoleAttr *, const Decl *) const;
+
+public:
+  bool isCached() const { return true; }
+};
+
 class ResolveTypeEraserTypeRequest
     : public SimpleRequest<ResolveTypeEraserTypeRequest,
                            Type (ProtocolDecl *, TypeEraserAttr *),
@@ -4032,28 +4051,6 @@ class ExpandAccessorMacros
   void noteCycleStep(DiagnosticEngine &diags) const;
 };
 
-/// Expand all conformance macros attached to the given declaration.
-///
-/// Produces the set of macro expansion buffer IDs.
-class ExpandConformanceMacros
-    : public SimpleRequest<ExpandConformanceMacros,
-                           ArrayRef<unsigned>(NominalTypeDecl *),
-                           RequestFlags::Cached> {
-public:
-  using SimpleRequest::SimpleRequest;
-
-private:
-  friend SimpleRequest;
-
-  ArrayRef<unsigned> evaluate(Evaluator &evaluator,
-                              NominalTypeDecl *nominal) const;
-
-public:
-  bool isCached() const { return true; }
-  void diagnoseCycle(DiagnosticEngine &diags) const;
-  void noteCycleStep(DiagnosticEngine &diags) const;
-};
-
 /// Expand all extension macros attached to the given declaration.
 ///
 /// Produces the set of macro expansion buffer IDs.

include/swift/AST/TypeCheckerTypeIDZone.def

@@ -360,6 +360,9 @@ SWIFT_REQUEST(TypeChecker, ResolveImplicitMemberRequest,
 SWIFT_REQUEST(TypeChecker, ResolveMacroRequest,
               ConcreteDeclRef(UnresolvedMacroReference, const Decl *),
               Cached, NoLocationInfo)
+SWIFT_REQUEST(TypeChecker, ResolveExtensionMacroConformances,
+              ArrayRef<Type>(const MacroRoleAttr *, const Decl *),
+              Cached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, ResolveTypeEraserTypeRequest,
               Type(ProtocolDecl *, TypeEraserAttr *),
               SeparatelyCached, NoLocationInfo)
@@ -457,9 +460,6 @@ SWIFT_REQUEST(TypeChecker, ExpandMemberAttributeMacros,
 SWIFT_REQUEST(TypeChecker, ExpandAccessorMacros,
               ArrayRef<unsigned>(AbstractStorageDecl *),
               Cached, NoLocationInfo)
-SWIFT_REQUEST(TypeChecker, ExpandConformanceMacros,
-              ArrayRef<unsigned>(NominalTypeDecl *),
-              Cached, NoLocationInfo)
 SWIFT_REQUEST(TypeChecker, ExpandExtensionMacros,
               ArrayRef<unsigned>(NominalTypeDecl *),
               Cached, NoLocationInfo)

lib/AST/ConformanceLookupTable.cpp

@@ -43,6 +43,9 @@ DeclContext *ConformanceLookupTable::ConformanceSource::getDeclContext() const {
 
   case ConformanceEntryKind::Synthesized:
     return getSynthesizedDeclContext();
+
+  case ConformanceEntryKind::PreMacroExpansion:
+    return getMacroGeneratedDeclContext();
   }
 
   llvm_unreachable("Unhandled ConformanceEntryKind in switch.");
@@ -104,6 +107,10 @@ void ConformanceLookupTable::ConformanceEntry::dump(raw_ostream &os,
   case ConformanceEntryKind::Synthesized:
     os << " synthesized";
     break;
+
+  case ConformanceEntryKind::PreMacroExpansion:
+    os << " unexpanded macro";
+    break;
   }
 
   if (auto conf = getConformance()) {
@@ -282,14 +289,8 @@ void ConformanceLookupTable::updateLookupTable(NominalTypeDecl *nominal,
           addInheritedProtocols(nominal,
                                 ConformanceSource::forExplicit(nominal));
 
-          // Expand conformance macros.
-          ASTContext &ctx = nominal->getASTContext();
-          (void)evaluateOrDefault(
-              ctx.evaluator, ExpandConformanceMacros{nominal}, { });
-
-          // Expand extension macros.
-          (void)evaluateOrDefault(
-              ctx.evaluator, ExpandExtensionMacros{nominal}, { });
+          addMacroGeneratedProtocols(
+              nominal, ConformanceSource::forUnexpandedMacro(nominal));
         },
         [&](ExtensionDecl *ext,
             ArrayRef<ConformanceConstructionInfo> protos) {
@@ -445,6 +446,7 @@ bool ConformanceLookupTable::addProtocol(ProtocolDecl *protocol, SourceLoc loc,
       switch (existingEntry->getKind()) {
       case ConformanceEntryKind::Explicit:
       case ConformanceEntryKind::Inherited:
+      case ConformanceEntryKind::PreMacroExpansion:
         return false;
 
       case ConformanceEntryKind::Implied:
@@ -495,6 +497,20 @@ void ConformanceLookupTable::addInheritedProtocols(
   }
 }
 
+void ConformanceLookupTable::addMacroGeneratedProtocols(
+    NominalTypeDecl *nominal, ConformanceSource source) {
+  nominal->forEachAttachedMacro(
+      MacroRole::Extension,
+      [&](CustomAttr *attr, MacroDecl *macro) {
+        SmallVector<ProtocolDecl *, 2> conformances;
+        macro->getIntroducedConformances(nominal, conformances);
+
+        for (auto *protocol : conformances) {
+          addProtocol(protocol, attr->getLocation(), source);
+        }
+      });
+}
+
 void ConformanceLookupTable::expandImpliedConformances(NominalTypeDecl *nominal,
                                                        DeclContext *dc) {
   // Note: recursive type-checking implies that AllConformances
@@ -534,6 +550,7 @@ static bool isReplaceable(ConformanceEntryKind kind) {
   switch (kind) {
   case ConformanceEntryKind::Implied:
   case ConformanceEntryKind::Synthesized:
+  case ConformanceEntryKind::PreMacroExpansion:
     return true;
 
   case ConformanceEntryKind::Explicit:
@@ -562,6 +579,23 @@ ConformanceLookupTable::Ordering ConformanceLookupTable::compareConformances(
             : Ordering::After);
   }
 
+  ConformanceEntryKind lhsKind = lhs->getRankingKind();
+  ConformanceEntryKind rhsKind = rhs->getRankingKind();
+
+  // Pre-expanded macro conformances are always superseded by
+  // conformances written in source. If the conformance is not
+  // written in the original source, the pre-expanded conformance
+  // will be superseded by the conformance in the macro expansion
+  // buffer.
+  if (lhsKind == ConformanceEntryKind::PreMacroExpansion ||
+      rhsKind == ConformanceEntryKind::PreMacroExpansion) {
+    if (lhsKind != rhsKind) {
+      return (lhs->getKind() < rhs->getKind()
+              ? Ordering::Before
+              : Ordering::After);
+    }
+  }
+
   // If one entry is fixed and the other is not, we have our answer.
   if (lhs->isFixed() != rhs->isFixed()) {
     auto isReplaceableOrMarker = [](ConformanceEntry *entry) -> bool {
@@ -584,9 +618,6 @@ ConformanceLookupTable::Ordering ConformanceLookupTable::compareConformances(
     return lhs->isFixed() ? Ordering::Before : Ordering::After;
   }
 
-  ConformanceEntryKind lhsKind = lhs->getRankingKind();
-  ConformanceEntryKind rhsKind = rhs->getRankingKind();
-
   if (lhsKind != ConformanceEntryKind::Implied ||
       rhsKind != ConformanceEntryKind::Implied) {
     // If both conformances are non-replaceable, diagnose the

lib/AST/ConformanceLookupTable.h

@@ -83,13 +83,15 @@ class ConformanceLookupTable : public ASTAllocated<ConformanceLookupTable> {
   /// Describes the "source" of a conformance, indicating where the
   /// conformance came from.
   class ConformanceSource {
-    llvm::PointerIntPair<void *, 2, ConformanceEntryKind> Storage;
+    void *Storage;
+
+    ConformanceEntryKind Kind;
 
     /// The location of the "unchecked" attribute, if there is one.
     SourceLoc uncheckedLoc;
 
     ConformanceSource(void *ptr, ConformanceEntryKind kind) 
-      : Storage(ptr, kind) { }
+      : Storage(ptr), Kind(kind) { }
 
   public:
     /// Create an inherited conformance.
@@ -126,6 +128,10 @@ class ConformanceLookupTable : public ASTAllocated<ConformanceLookupTable> {
       return ConformanceSource(dc, ConformanceEntryKind::Synthesized);
     }
 
+    static ConformanceSource forUnexpandedMacro(DeclContext *dc) {
+      return ConformanceSource(dc, ConformanceEntryKind::PreMacroExpansion);
+    }
+
     /// Return a new conformance source with the given location of "@unchecked".
     ConformanceSource withUncheckedLoc(SourceLoc uncheckedLoc) {
       ConformanceSource result(*this);
@@ -135,7 +141,7 @@ class ConformanceLookupTable : public ASTAllocated<ConformanceLookupTable> {
     }
 
     /// Retrieve the kind of conformance formed from this source.
-    ConformanceEntryKind getKind() const { return Storage.getInt(); }
+    ConformanceEntryKind getKind() const { return Kind; }
 
     /// Retrieve kind of the conformance for ranking purposes.
     ///
@@ -148,6 +154,7 @@ class ConformanceLookupTable : public ASTAllocated<ConformanceLookupTable> {
       case ConformanceEntryKind::Explicit:
       case ConformanceEntryKind::Inherited:
       case ConformanceEntryKind::Synthesized:
+      case ConformanceEntryKind::PreMacroExpansion:
         return kind;
 
       case ConformanceEntryKind::Implied:
@@ -169,28 +176,33 @@ class ConformanceLookupTable : public ASTAllocated<ConformanceLookupTable> {
     /// for the inheriting class.
     ClassDecl *getInheritingClass() const {
       assert(getKind() == ConformanceEntryKind::Inherited);
-      return static_cast<ClassDecl *>(Storage.getPointer());      
+      return static_cast<ClassDecl *>(Storage);
     }
 
     /// For an explicit conformance, retrieve the declaration context
     /// that specifies the conformance.
     DeclContext *getExplicitDeclContext() const {
       assert(getKind() == ConformanceEntryKind::Explicit);
-      return static_cast<DeclContext *>(Storage.getPointer());      
+      return static_cast<DeclContext *>(Storage);
+    }
+
+    DeclContext *getMacroGeneratedDeclContext() const {
+      assert(getKind() == ConformanceEntryKind::PreMacroExpansion);
+      return static_cast<DeclContext *>(Storage);
     }
 
     /// For a synthesized conformance, retrieve the nominal type decl
     /// that will receive the conformance.
     ConformanceEntry *getImpliedSource() const {
       assert(getKind() == ConformanceEntryKind::Implied);
-      return static_cast<ConformanceEntry *>(Storage.getPointer());
+      return static_cast<ConformanceEntry *>(Storage);
     }
 
     /// For a synthesized conformance, retrieve the nominal type decl
     /// that will receive the conformance.
     DeclContext *getSynthesizedDeclContext() const {
       assert(getKind() == ConformanceEntryKind::Synthesized);
-      return static_cast<DeclContext *>(Storage.getPointer());
+      return static_cast<DeclContext *>(Storage);
     }
 
     /// Get the declaration context that this conformance will be
@@ -226,6 +238,10 @@ class ConformanceLookupTable : public ASTAllocated<ConformanceLookupTable> {
 
     /// Whether this conformance is already "fixed" and cannot be superseded.
     bool isFixed() const {
+      // A conformance from an unexpanded macro can always be superseded.
+      if (getKind() == ConformanceEntryKind::PreMacroExpansion)
+        return true;
+
       // If a conformance has been assigned, it cannot be superseded.
       if (getConformance())
         return true;
@@ -235,6 +251,7 @@ class ConformanceLookupTable : public ASTAllocated<ConformanceLookupTable> {
       case ConformanceEntryKind::Explicit:
       case ConformanceEntryKind::Implied:
       case ConformanceEntryKind::Synthesized:
+      case ConformanceEntryKind::PreMacroExpansion:
         return false;
 
       case ConformanceEntryKind::Inherited:
@@ -341,6 +358,11 @@ class ConformanceLookupTable : public ASTAllocated<ConformanceLookupTable> {
       llvm::PointerUnion<const TypeDecl *, const ExtensionDecl *> decl,
       ConformanceSource source);
 
+  /// Add the protocols added by attached extension macros that are not
+  /// yet expanded.
+  void addMacroGeneratedProtocols(
+      NominalTypeDecl *nominal, ConformanceSource source);
+
   /// Expand the implied conformances for the given DeclContext.
   void expandImpliedConformances(NominalTypeDecl *nominal, DeclContext *dc);