Merge pull request swiftlang#18539 from DougGregor/unqualified-lookup-via-decls

 [Name lookup] Use decl-based name lookup more regularly

Author: DougGregor

include/swift/AST/Decl.h

@@ -488,7 +488,7 @@ class alignas(1 << DeclAlignInBits) Decl {
     HasLazyConformances : 1
   );
 
-  SWIFT_INLINE_BITFIELD_FULL(ProtocolDecl, NominalTypeDecl, 1+1+1+1+1+1+1+1+2+8+16,
+  SWIFT_INLINE_BITFIELD_FULL(ProtocolDecl, NominalTypeDecl, 1+1+1+1+1+1+1+2+8+16,
     /// Whether the \c RequiresClass bit is valid.
     RequiresClassValid : 1,
 
@@ -511,9 +511,6 @@ class alignas(1 << DeclAlignInBits) Decl {
     /// because they could not be imported from Objective-C).
     HasMissingRequirements : 1,
 
-    /// Whether we are currently computing inherited protocols.
-    ComputingInheritedProtocols : 1,
-
     /// The stage of the circularity check for this protocol.
     Circularity : 2,
 

include/swift/AST/LazyResolver.h

@@ -72,16 +72,6 @@ class LazyResolver {
   /// considered to be members of the extended type.
   virtual void resolveExtension(ExtensionDecl *ext) = 0;
 
-  using ConformanceConstructionInfo = std::pair<SourceLoc, ProtocolDecl *>;
-  /// Resolve enough of an extension to find which protocols it is declaring
-  /// conformance to.
-  ///
-  /// This can be called to ensure that the "extension Foo: Bar, Baz" part of
-  /// the extension is understood.
-  virtual void resolveExtensionForConformanceConstruction(
-      ExtensionDecl *ext,
-      SmallVectorImpl<ConformanceConstructionInfo> &protocols) = 0;
-
   /// Resolve any implicitly-declared constructors within the given nominal.
   virtual void resolveImplicitConstructors(NominalTypeDecl *nominal) = 0;
 

include/swift/AST/NameLookupRequests.h

@@ -184,6 +184,30 @@ class ExtendedNominalRequest :
   void noteCycleStep(DiagnosticEngine &diags) const;
 };
 
+/// Request the nominal types that occur as the right-hand side of "Self: Foo"
+/// constraints in the "where" clause of a protocol extension.
+class SelfBoundsFromWhereClauseRequest :
+    public SimpleRequest<SelfBoundsFromWhereClauseRequest,
+                         CacheKind::Uncached,
+                         llvm::TinyPtrVector<NominalTypeDecl *>,
+                         ExtensionDecl *> {
+public:
+  using SimpleRequest::SimpleRequest;
+
+private:
+  friend class SimpleRequest;
+
+  // Evaluation.
+  llvm::TinyPtrVector<NominalTypeDecl *> evaluate(Evaluator &evaluator,
+                                                  ExtensionDecl *ext) const;
+
+public:
+  // Cycle handling
+  llvm::TinyPtrVector<NominalTypeDecl *> breakCycle() const { return { }; }
+  void diagnoseCycle(DiagnosticEngine &diags) const;
+  void noteCycleStep(DiagnosticEngine &diags) const;
+};
+
 /// The zone number for name-lookup requests.
 #define SWIFT_NAME_LOOKUP_REQUESTS_TYPEID_ZONE 9
 

include/swift/AST/NameLookupTypeIDZone.def

@@ -18,3 +18,4 @@ SWIFT_TYPEID(InheritedDeclsReferencedRequest)
 SWIFT_TYPEID(UnderlyingTypeDeclsReferencedRequest)
 SWIFT_TYPEID(SuperclassDeclRequest)
 SWIFT_TYPEID(ExtendedNominalRequest)
+SWIFT_TYPEID(SelfBoundsFromWhereClauseRequest)

lib/AST/ASTVerifier.cpp

@@ -2490,31 +2490,6 @@ class Verifier : public ASTWalker {
       }
     }
 
-    /// Check the given list of protocols.
-    void verifyProtocolList(Decl *decl, ArrayRef<ProtocolDecl *> protocols) {
-      PrettyStackTraceDecl debugStack("verifying ProtocolList", decl);
-
-      // Make sure that the protocol list is fully expanded.
-      SmallVector<ProtocolDecl *, 4> nominalProtocols(protocols.begin(),
-                                                      protocols.end());
-      ProtocolType::canonicalizeProtocols(nominalProtocols);
-
-      SmallVector<Type, 4> protocolTypes;
-      for (auto proto : protocols)
-        protocolTypes.push_back(proto->getDeclaredType());
-      auto type = ProtocolCompositionType::get(Ctx, protocolTypes,
-                                               /*HasExplicitAnyObject=*/false);
-      auto layout = type->getExistentialLayout();
-      SmallVector<ProtocolDecl *, 4> canonicalProtocols;
-      for (auto *protoTy : layout.getProtocols())
-        canonicalProtocols.push_back(protoTy->getDecl());
-      if (nominalProtocols != canonicalProtocols) {
-        dumpRef(decl);
-        Out << " doesn't have a complete set of protocols\n";
-        abort();
-      }      
-    }
-
     /// Verify that the given conformance makes sense for the given
     /// type.
     void verifyConformance(Type type, ProtocolConformanceRef conformance) {
@@ -2731,9 +2706,6 @@ class Verifier : public ASTWalker {
     }
 
     void verifyChecked(NominalTypeDecl *nominal) {
-      // Make sure that the protocol list is fully expanded.
-      verifyProtocolList(nominal, nominal->getLocalProtocols());
-
       // Make sure that the protocol conformances are complete.
       // Only do so within the source file of the nominal type,
       // because anywhere else this can trigger new type-check requests.
@@ -2749,9 +2721,6 @@ class Verifier : public ASTWalker {
     }
 
     void verifyChecked(ExtensionDecl *ext) {
-      // Make sure that the protocol list is fully expanded.
-      verifyProtocolList(ext, ext->getLocalProtocols());
-
       // Make sure that the protocol conformances are complete.
       for (auto conformance : ext->getLocalConformances()) {
         verifyConformance(ext, conformance);