[AST] Eliminate the "interface type" from protocol conformances.

We don't need this notion.

Author: DougGregor

include/swift/AST/ProtocolConformance.h

@@ -94,14 +94,9 @@ class alignas(1 << DeclAlignInBits) ProtocolConformance {
   /// conformance definition.
   Type ConformingType;
 
-  /// \brief The interface type that conforms to the protocol.
-  Type ConformingInterfaceType;
-
 protected:
-  ProtocolConformance(ProtocolConformanceKind kind, Type conformingType,
-                      Type conformingInterfaceType)
-    : Kind(kind), ConformingType(conformingType),
-      ConformingInterfaceType(conformingInterfaceType) { }
+  ProtocolConformance(ProtocolConformanceKind kind, Type conformingType)
+    : Kind(kind), ConformingType(conformingType) { }
 
 public:
   /// Determine the kind of protocol conformance.
@@ -110,9 +105,6 @@ class alignas(1 << DeclAlignInBits) ProtocolConformance {
   /// Get the conforming type.
   Type getType() const { return ConformingType; }
 
-  /// Get the conforming interface type.
-  Type getInterfaceType() const { return ConformingInterfaceType; }
-  
   /// Get the protocol being conformed to.
   ProtocolDecl *getProtocol() const;
 
@@ -357,9 +349,7 @@ class NormalProtocolConformance : public ProtocolConformance,
   NormalProtocolConformance(Type conformingType, ProtocolDecl *protocol,
                             SourceLoc loc, DeclContext *dc,
                             ProtocolConformanceState state)
-    : ProtocolConformance(ProtocolConformanceKind::Normal, conformingType,
-                          // FIXME: interface type should be passed in
-                          dc->getDeclaredInterfaceType()),
+    : ProtocolConformance(ProtocolConformanceKind::Normal, conformingType),
       ProtocolAndState(protocol, state), Loc(loc), ContextAndInvalid(dc, false)
   {
   }
@@ -369,9 +359,7 @@ class NormalProtocolConformance : public ProtocolConformance,
                             ProtocolDecl *protocol,
                             SourceLoc loc, AbstractStorageDecl *behaviorStorage,
                             ProtocolConformanceState state)
-    : ProtocolConformance(ProtocolConformanceKind::Normal, conformingType,
-                          // FIXME: interface type should be passed in
-                          conformingInterfaceType),
+    : ProtocolConformance(ProtocolConformanceKind::Normal, conformingType),
       ProtocolAndState(protocol, state), Loc(loc),
       ContextAndInvalid(behaviorStorage, false)
   {
@@ -640,9 +628,7 @@ class InheritedProtocolConformance : public ProtocolConformance,
 
   InheritedProtocolConformance(Type conformingType,
                                ProtocolConformance *inheritedConformance)
-    : ProtocolConformance(ProtocolConformanceKind::Inherited, conformingType,
-            // FIXME: interface type should be passed in
-            inheritedConformance->getDeclContext()->getDeclaredInterfaceType()),
+    : ProtocolConformance(ProtocolConformanceKind::Inherited, conformingType),
       InheritedConformance(inheritedConformance)
   {
   }

lib/AST/ASTMangler.cpp

@@ -1839,7 +1839,10 @@ void ASTMangler::appendProtocolConformance(const ProtocolConformance *conformanc
     appendProtocolName(conformance->getProtocol());
     appendIdentifier(behaviorStorage->getName().str());
   } else {
-    appendType(conformance->getInterfaceType()->getCanonicalType());
+    auto conformanceDC = conformance->getDeclContext();
+    auto conformingType =
+      conformanceDC->mapTypeOutOfContext(conformance->getType());
+    appendType(conformingType->getCanonicalType());
     appendProtocolName(conformance->getProtocol());
     appendModule(conformance->getDeclContext()->getParentModule());
   }

lib/AST/ProtocolConformance.cpp

@@ -266,7 +266,7 @@ usesDefaultDefinition(AssociatedTypeDecl *requirement) const {
 bool ProtocolConformance::hasFixedLayout() const {
   // A conformance/witness table has fixed layout if type has a fixed layout in
   // all resilience domains, and the conformance is externally visible.
-  if (auto nominal = getInterfaceType()->getAnyNominal())
+  if (auto nominal = getType()->getAnyNominal())
     if (nominal->hasFixedLayout() &&
         getProtocol()->getEffectiveAccess() >= Accessibility::Public &&
         nominal->getEffectiveAccess() >= Accessibility::Public)
@@ -652,11 +652,7 @@ SpecializedProtocolConformance::SpecializedProtocolConformance(
     Type conformingType,
     ProtocolConformance *genericConformance,
     SubstitutionList substitutions)
-  : ProtocolConformance(ProtocolConformanceKind::Specialized, conformingType,
-                        // FIXME: interface type should be passed in.
-                        // assumes specialized conformance is always fully
-                        // specialized
-                        conformingType),
+  : ProtocolConformance(ProtocolConformanceKind::Specialized, conformingType),
     GenericConformance(genericConformance),
     GenericSubstitutions(substitutions)
 {
@@ -1068,8 +1064,6 @@ bool ProtocolConformance::isCanonical() const {
 
   if (!getType()->isCanonical())
     return false;
-  if (!getInterfaceType()->isCanonical())
-    return false;
 
   switch (getKind()) {
   case ProtocolConformanceKind::Normal: {

lib/IRGen/GenReflection.cpp

@@ -283,7 +283,7 @@ class AssociatedTypeMetadataBuilder : public ReflectionMetadataBuilder {
   void layout() override {
     // If the conforming type is generic, we just want to emit the
     // unbound generic type here.
-    auto *Nominal = Conformance->getInterfaceType()->getAnyNominal();
+    auto *Nominal = Conformance->getType()->getAnyNominal();
     assert(Nominal && "Structural conformance?");
 
     PrettyStackTraceDecl DebugStack("emitting associated type metadata",

lib/SILGen/SILGenType.cpp

@@ -608,7 +608,9 @@ SILGenModule::emitProtocolWitness(ProtocolConformance *conformance,
     genericEnv = witnessRef.getDecl()->getInnermostDeclContext()
                    ->getGenericEnvironmentOfContext();
 
-    Type concreteTy = conformance->getInterfaceType();
+    auto conformanceDC = conformance->getDeclContext();
+    Type concreteTy =
+      conformanceDC->mapTypeOutOfContext(conformance->getType());
 
     // FIXME: conformance substitutions should be in terms of interface types
     auto specialized = conformance;
@@ -672,7 +674,9 @@ SILGenModule::emitProtocolWitness(ProtocolConformance *conformance,
   // If the witness is a free function, there is no Self type.
   if (!isFree) {
     if (conformance) {
-      selfInterfaceType = conformance->getInterfaceType();
+      auto conformanceDC = conformance->getDeclContext();
+      selfInterfaceType =
+        conformanceDC->mapTypeOutOfContext(conformance->getType());
     } else {
       auto *proto = cast<ProtocolDecl>(requirement.getDecl()->getDeclContext());
       selfInterfaceType = proto->getSelfInterfaceType();

lib/Sema/TypeCheckDecl.cpp

@@ -3151,7 +3151,8 @@ static void checkVarBehavior(VarDecl *decl, TypeChecker &TC) {
 
   auto dc = decl->getDeclContext();
   auto behaviorSelf = conformance->getType();
-  auto behaviorInterfaceSelf = conformance->getInterfaceType();
+  auto behaviorInterfaceSelf =
+    conformance->getDeclContext()->mapTypeOutOfContext(behaviorSelf);
   auto behaviorProto = conformance->getProtocol();
   auto behaviorProtoTy = behaviorProto->getDeclaredType();