Merge pull request #2565 from jckarter/extension-conformance-sema-order

	ConformanceLookupTable: Recursively inherit into subclasses when incrementally adding extension conformances.

Author: jckarter

include/swift/AST/Decl.h

@@ -3203,6 +3203,10 @@ class ClassDecl : public NominalTypeDecl {
   /// Retrieve the superclass of this class, or null if there is no superclass.
   Type getSuperclass() const { return LazySemanticInfo.Superclass.getPointer(); }
 
+  /// Retrieve the ClassDecl for the superclass of this class, or null if there
+  /// is no superclass.
+  ClassDecl *getSuperclassDecl() const;
+
   /// Set the superclass of this class.
   void setSuperclass(Type superclass) {
     LazySemanticInfo.Superclass.setPointerAndInt(superclass, true);

include/swift/AST/TypeAlignments.h

@@ -33,6 +33,7 @@ namespace swift {
   class Decl;
   class DeclContext;
   class Expr;
+  class ExtensionDecl;
   class GenericTypeParamDecl;
   class NormalProtocolConformance;
   class OperatorDecl;
@@ -80,6 +81,7 @@ LLVM_DECLARE_TYPE_ALIGNMENT(swift::GenericTypeParamDecl, swift::DeclAlignInBits)
 LLVM_DECLARE_TYPE_ALIGNMENT(swift::OperatorDecl, swift::DeclAlignInBits)
 LLVM_DECLARE_TYPE_ALIGNMENT(swift::ProtocolDecl, swift::DeclAlignInBits)
 LLVM_DECLARE_TYPE_ALIGNMENT(swift::ValueDecl, swift::DeclAlignInBits)
+LLVM_DECLARE_TYPE_ALIGNMENT(swift::ExtensionDecl, swift::DeclAlignInBits)
 
 LLVM_DECLARE_TYPE_ALIGNMENT(swift::TypeBase, swift::TypeAlignInBits)
 LLVM_DECLARE_TYPE_ALIGNMENT(swift::ArchetypeType, swift::TypeAlignInBits)

lib/AST/ConformanceLookupTable.cpp

@@ -141,9 +141,10 @@ void ConformanceLookupTable::forEachInStage(ConformanceStage stage,
                                             ExtensionFunc extensionFunc) {
   assert(static_cast<unsigned>(stage) < NumConformanceStages &&
          "NumConformanceStages has not been updated");
-  LastProcessedEntry &lastProcessed
-    = LastProcessed[static_cast<unsigned>(stage)];
 
+  LastProcessedEntry &lastProcessed
+    = LastProcessed[nominal][static_cast<unsigned>(stage)];
+  
   // Handle the nominal type.
   if (!lastProcessed.getInt()) {
     lastProcessed.setInt(true);
@@ -300,23 +301,26 @@ void ConformanceLookupTable::updateLookupTable(NominalTypeDecl *nominal,
       if (resolver)
         resolver->resolveSuperclass(classDecl);
 
-      if (Type superclass = classDecl->getSuperclass()) {
-        if (auto superclassDecl 
-              = superclass->getClassOrBoundGenericClass()) {
-          // Break infinite recursion when visiting ill-formed classes
-          // with circular inheritance.
-          if (VisitingSuperclass)
-            return;
-          llvm::SaveAndRestore<bool> visiting(VisitingSuperclass, true);
-
-          // Resolve the conformances of the superclass.
-          superclassDecl->prepareConformanceTable();
-          superclassDecl->ConformanceTable->updateLookupTable(
-            superclassDecl,
-            ConformanceStage::Resolved,
-            resolver);
-          
-          // Expand inherited conformances.
+      if (auto superclassDecl = classDecl->getSuperclassDecl()) {
+        // Break infinite recursion when visiting ill-formed classes
+        // with circular inheritance.
+        if (VisitingSuperclass)
+          return;
+        llvm::SaveAndRestore<bool> visiting(VisitingSuperclass, true);
+
+        // Resolve the conformances of the superclass.
+        superclassDecl->prepareConformanceTable();
+        superclassDecl->ConformanceTable->updateLookupTable(
+          superclassDecl,
+          ConformanceStage::Resolved,
+          resolver);
+        
+        // Expand inherited conformances from all superclasses.
+        // We may have circular inheritance in ill-formed classes, so keep an
+        // eye out for that.
+        auto circularSuperclass = superclassDecl->getSuperclassDecl();
+        
+        do {
           forEachInStage(stage, superclassDecl, resolver,
                          [&](NominalTypeDecl *superclass) {
                            inheritConformances(classDecl, superclassDecl,
@@ -326,7 +330,12 @@ void ConformanceLookupTable::updateLookupTable(NominalTypeDecl *nominal,
                            inheritConformances(classDecl, superclassDecl, ext,
                                                resolver);
                          });
-        }
+          superclassDecl = superclassDecl->getSuperclassDecl();
+          if (circularSuperclass)
+            circularSuperclass = circularSuperclass->getSuperclassDecl();
+          if (circularSuperclass)
+            circularSuperclass = circularSuperclass->getSuperclassDecl();
+        } while (superclassDecl != circularSuperclass);
       }
     }
     break;    
@@ -742,11 +751,11 @@ DeclContext *ConformanceLookupTable::getConformingContext(
       return nullptr;
 
     // If we had a circular dependency, the superclass may not exist.
-    if (!classDecl->getSuperclass())
-      return nullptr;
-        
     auto superclassDecl
-      = classDecl->getSuperclass()->getClassOrBoundGenericClass();
+      = classDecl->getSuperclassDecl();
+    
+    if (!superclassDecl)
+      return nullptr;
 
     if (!classDecl->ConformanceTable->VisitingSuperclass) {
       llvm::SaveAndRestore<bool> visiting(

lib/AST/ConformanceLookupTable.h

@@ -27,6 +27,7 @@
 #include "llvm/ADT/MapVector.h"
 #include "llvm/ADT/PointerUnion.h"
 #include "llvm/ADT/SetVector.h"
+#include <unordered_map>
 
 namespace swift {
 
@@ -67,11 +68,16 @@ class ConformanceLookupTable {
   /// at that stage.
   typedef llvm::PointerIntPair<ExtensionDecl *, 1, bool> LastProcessedEntry;
 
-  /// Array indicating how far we have gotten in processing the
+  /// Array indicating how far we have gotten in processing each
   /// nominal type and list of extensions for each stage of
   /// conformance checking.
-  LastProcessedEntry LastProcessed[NumConformanceStages];
-
+  ///
+  /// Uses std::unordered_map instead of DenseMap so that stable interior
+  /// references can be taken.
+  std::unordered_map<NominalTypeDecl *,
+                     std::array<LastProcessedEntry, NumConformanceStages>>
+  LastProcessed;
+  
   /// The list of parsed extension declarations that have been delayed because
   /// no resolver was available at the time.
   ///

lib/AST/Decl.cpp

@@ -4677,3 +4677,9 @@ Type TypeBase::getSwiftNewtypeUnderlyingType() {
 
   return {};
 }
+
+ClassDecl *ClassDecl::getSuperclassDecl() const {
+  if (auto superclass = getSuperclass())
+    return superclass->getClassOrBoundGenericClass();
+    return nullptr;
+}

lib/ClangImporter/ImportDecl.cpp

@@ -4838,7 +4838,7 @@ namespace {
 
       // Synthesize trivial conformances for each of the protocols.
       SmallVector<ProtocolConformance *, 4> conformances;
-;
+
       auto dc = decl->getInnermostDeclContext();
       auto &ctx = Impl.SwiftContext;
       for (unsigned i = 0, n = protocols.size(); i != n; ++i) {

lib/SILGen/SILGenPattern.cpp

@@ -1171,7 +1171,8 @@ void PatternMatchEmission::bindNamedPattern(NamedPattern *pattern,
                                             bool forIrrefutableRow,
                                             bool hasMultipleItems) {
   bindVariable(pattern, pattern->getDecl(), value,
-               pattern->getType()->getCanonicalType(), forIrrefutableRow, hasMultipleItems);
+               pattern->getType()->getCanonicalType(), forIrrefutableRow,
+               hasMultipleItems);
 }
 
 /// Should we take control of the mang

test/decl/ext/Inputs/extension-inheritance-conformance-objc-multi-file-2.swift

@@ -0,0 +1,2 @@
+extension Responder {}
+extension View {}

test/decl/ext/Inputs/extension-inheritance-conformance-objc.h

@@ -0,0 +1,11 @@
+__attribute__((objc_root_class))
+@interface Object
++alloc;
+-init;
+@end
+
+@interface Responder: Object
+@end
+
+@interface View: Responder
+@end

test/decl/ext/extension-inheritance-conformance-native.swift

@@ -0,0 +1,20 @@
+// RUN: %target-swift-frontend -parse -verify %s
+
+class Object {}
+class Responder: Object {}
+class View: Responder {}
+
+extension View {}
+
+protocol Foo {}
+
+extension Foo {
+  func bar() -> Self { return self }
+}
+
+extension Object: Foo {}
+
+_ = Object().bar()
+_ = Responder().bar()
+_ = View().bar()
+