Allow PlaceholderType Originator to be TypeRepr not just PlaceholderTypeRepr

Author: Greg Titus

include/swift/AST/Types.h

@@ -7327,7 +7327,7 @@ class PlaceholderType : public TypeBase {
   // recursive property logic in PlaceholderType::get.
   using Originator =
       llvm::PointerUnion<TypeVariableType *, DependentMemberType *, VarDecl *,
-                         ErrorExpr *, PlaceholderTypeRepr *>;
+                         ErrorExpr *, TypeRepr *>;
 
   Originator O;
 

include/swift/Sema/ConstraintLocator.h

@@ -985,13 +985,13 @@ class LocatorPathElt::ConformanceRequirement final
 };
 
 class LocatorPathElt::PlaceholderType final
-    : public StoredPointerElement<PlaceholderTypeRepr> {
+    : public StoredPointerElement<TypeRepr> {
 public:
-  PlaceholderType(PlaceholderTypeRepr *placeholderRepr)
+  PlaceholderType(TypeRepr *placeholderRepr)
       : StoredPointerElement(PathElementKind::PlaceholderType,
                              placeholderRepr) {}
 
-  PlaceholderTypeRepr *getPlaceholderRepr() const { return getStoredPointer(); }
+  TypeRepr *getPlaceholderRepr() const { return getStoredPointer(); }
 
   static bool classof(const LocatorPathElt *elt) {
     return elt->getKind() == ConstraintLocator::PlaceholderType;

lib/AST/ASTDumper.cpp

@@ -3987,8 +3987,8 @@ namespace {
         printFlag("error_expr");
       } else if (auto *DMT = originator.dyn_cast<DependentMemberType *>()) {
         printRec(DMT, "dependent_member_type");
-      } else if (originator.is<PlaceholderTypeRepr *>()) {
-        printFlag("placeholder_type_repr");
+      } else if (originator.is<TypeRepr *>()) {
+        printFlag("type_repr");
       } else {
         assert(false && "unknown originator");
       }

lib/AST/ASTPrinter.cpp

@@ -5870,8 +5870,8 @@ class TypePrinter : public TypeVisitor<TypePrinter> {
         Printer << "error_expr";
       } else if (auto *DMT = originator.dyn_cast<DependentMemberType *>()) {
         visit(DMT);
-      } else if (originator.is<PlaceholderTypeRepr *>()) {
-        Printer << "placeholder_type_repr";
+      } else if (originator.is<TypeRepr *>()) {
+        Printer << "type_repr";
       } else {
         assert(false && "unknown originator");
       }

lib/Sema/CSDiagnostics.cpp

@@ -9360,7 +9360,7 @@ bool InvalidMemberReferenceWithinInitAccessor::diagnoseAsError() {
 }
 
 bool ConcreteTypeSpecialization::diagnoseAsError() {
-  emitDiagnostic(diag::not_a_generic_type, resolveType(ConcreteType));
+  emitDiagnostic(diag::not_a_generic_type, ConcreteType);
   return true;
 }
 

lib/Sema/CSDiagnostics.h

@@ -3132,7 +3132,7 @@ class ConcreteTypeSpecialization final : public FailureDiagnostic {
   ConcreteTypeSpecialization(const Solution &solution, Type concreteTy,
                              ConstraintLocator *locator)
       : FailureDiagnostic(solution, locator),
-        ConcreteType(concreteTy) {}
+        ConcreteType(resolveType(concreteTy)) {}
 
   bool diagnoseAsError() override;
 };

lib/Sema/CSGen.cpp

@@ -1924,8 +1924,7 @@ namespace {
             OpenPackElementType(CS, locator, elementEnv));
         if (result->hasError()) {
           auto &ctxt = CS.getASTContext();
-          auto *repr = new (ctxt) PlaceholderTypeRepr(specializationArg->getLoc());
-          result = PlaceholderType::get(ctxt, repr);
+          result = PlaceholderType::get(ctxt, specializationArg);
           ctxt.Diags.diagnose(lAngleLoc,
                               diag::while_parsing_as_left_angle_bracket);
         }
@@ -4802,11 +4801,11 @@ bool ConstraintSystem::generateConstraints(
         // If we have a placeholder originating from a PlaceholderTypeRepr,
         // tack that on to the locator.
         if (auto *placeholderTy = ty->getAs<PlaceholderType>())
-          if (auto *placeholderRepr = placeholderTy->getOriginator()
-                                          .dyn_cast<PlaceholderTypeRepr *>())
+          if (auto *typeRepr = placeholderTy->getOriginator()
+                                          .dyn_cast<TypeRepr *>())
             return getConstraintLocator(
                 convertTypeLocator,
-                LocatorPathElt::PlaceholderType(placeholderRepr));
+                LocatorPathElt::PlaceholderType(typeRepr));
         return convertTypeLocator;
       };
 

lib/Sema/ConstraintSystem.cpp

@@ -1077,17 +1077,17 @@ Type ConstraintSystem::replaceInferableTypesWithTypeVars(
         return openUnboundGenericType(unbound->getDecl(), unbound->getParent(),
                                       locator, /*isTypeResolution=*/false);
       } else if (auto *placeholderTy = type->getAs<PlaceholderType>()) {
-        if (auto *placeholderRepr = placeholderTy->getOriginator()
-                                        .dyn_cast<PlaceholderTypeRepr *>()) {
-
-          return createTypeVariable(
-              getConstraintLocator(
-                  locator, LocatorPathElt::PlaceholderType(placeholderRepr)),
-              TVO_CanBindToNoEscape | TVO_PrefersSubtypeBinding |
-                  TVO_CanBindToHole);
-        }
-
-        if (auto *var = placeholderTy->getOriginator().dyn_cast<VarDecl *>()) {
+        if (auto *typeRepr =
+                placeholderTy->getOriginator().dyn_cast<TypeRepr *>()) {
+          if (isa<PlaceholderTypeRepr>(typeRepr)) {
+            return createTypeVariable(
+                getConstraintLocator(locator,
+                                     LocatorPathElt::PlaceholderType(typeRepr)),
+                TVO_CanBindToNoEscape | TVO_PrefersSubtypeBinding |
+                    TVO_CanBindToHole);
+          }
+        } else if (auto *var =
+                       placeholderTy->getOriginator().dyn_cast<VarDecl *>()) {
           if (var->getName().hasDollarPrefix()) {
             auto *repr =
                 new (type->getASTContext()) PlaceholderTypeRepr(var->getLoc());

lib/Sema/TypeCheckDeclPrimary.cpp

@@ -1171,7 +1171,8 @@ void TypeChecker::notePlaceholderReplacementTypes(Type writtenType,
       }
 
       if (auto *origRepr =
-              placeholder->getOriginator().dyn_cast<PlaceholderTypeRepr *>()) {
+              placeholder->getOriginator().dyn_cast<TypeRepr *>()) {
+        assert(isa<PlaceholderTypeRepr>(origRepr));
         t1->getASTContext()
             .Diags
             .diagnose(origRepr->getLoc(),