Some cleanup to remove more IUO related things.

include/swift/AST/Types.h

@@ -993,10 +993,6 @@ class alignas(1 << TypeAlignInBits) TypeBase {
   /// Return T if this type is Optional<T>; otherwise, return the null type.
   Type getOptionalObjectType();
 
-  /// Return T if this type is ImplicitlyUnwrappedOptional<T>; otherwise, return
-  /// the null type.
-  Type getImplicitlyUnwrappedOptionalObjectType();
-
   /// Return T if this type is Optional<T> or ImplicitlyUnwrappedOptional<T>;
   /// otherwise, return the null type.
   Type getAnyOptionalObjectType(OptionalTypeKind &kind);

lib/AST/Decl.cpp

@@ -1696,18 +1696,6 @@ static Type mapSignatureType(ASTContext &ctx, Type type) {
 
 /// Map a signature type for a parameter.
 static Type mapSignatureParamType(ASTContext &ctx, Type type) {
-  // Translate implicitly unwrapped optionals into strict optionals.
-  if (auto inOutTy = type->getAs<InOutType>()) {
-    if (auto uncheckedOptOf =
-            inOutTy->getObjectType()
-                ->getImplicitlyUnwrappedOptionalObjectType()) {
-      type = InOutType::get(OptionalType::get(uncheckedOptOf));
-    }
-  } else if (auto uncheckedOptOf =
-                 type->getImplicitlyUnwrappedOptionalObjectType()) {
-    type = OptionalType::get(uncheckedOptOf);
-  }
-
   return mapSignatureType(ctx, type);
 }
 

lib/AST/Type.cpp

@@ -502,13 +502,6 @@ Type TypeBase::getOptionalObjectType() {
   return Type();
 }
 
-Type TypeBase::getImplicitlyUnwrappedOptionalObjectType() {
-  if (auto boundTy = getAs<BoundGenericEnumType>())
-    if (boundTy->getDecl()->classifyAsOptionalType() == OTK_ImplicitlyUnwrappedOptional)
-      return boundTy->getGenericArgs()[0];
-  return Type();
-}
-
 Type TypeBase::getAnyOptionalObjectType(OptionalTypeKind &kind) {
   if (auto boundTy = getAs<BoundGenericEnumType>())
     if ((kind = boundTy->getDecl()->classifyAsOptionalType()))
@@ -2309,17 +2302,6 @@ static bool matches(CanType t1, CanType t2, TypeMatchOptions matchMode,
                                paramsAndResultMatch);
   }
 
-  if (matchMode.contains(TypeMatchFlags::AllowNonOptionalForIUOParam) &&
-      (paramPosition == ParameterPosition::Parameter ||
-       paramPosition == ParameterPosition::ParameterTupleElement) &&
-      insideOptional == OptionalUnwrapping::None) {
-    // Allow T to override T! in certain cases.
-    if (auto obj1 = t1->getImplicitlyUnwrappedOptionalObjectType()) {
-      t1 = obj1->getCanonicalType();
-      if (t1 == t2) return true;
-    }
-  }
-
   // Class-to-class.
   if (matchMode.contains(TypeMatchFlags::AllowOverride))
     if (t2->isExactSuperclassOf(t1))

lib/ClangImporter/ImportType.cpp

@@ -177,8 +177,6 @@ namespace {
     using TypeVisitor::Visit;
     ImportResult Visit(clang::QualType type) {
       auto IR = Visit(type.getTypePtr());
-      assert(!IR.AbstractType ||
-             !IR.AbstractType->getImplicitlyUnwrappedOptionalObjectType());
       return IR;
     }
 
@@ -1161,10 +1159,6 @@ static ImportedType adjustTypeForConcreteImport(
     bool allowNSUIntegerAsInt, Bridgeability bridging, OptionalTypeKind optKind,
     bool resugarNSErrorPointer) {
 
-  // We never expect an IUO type to be passed in.
-  assert(!importedType ||
-         !importedType->getImplicitlyUnwrappedOptionalObjectType());
-
   if (importKind == ImportTypeKind::Abstract) {
     return {importedType, false};
   }
@@ -1188,8 +1182,6 @@ static ImportedType adjustTypeForConcreteImport(
   if (!importedType)
     return {Type(), false};
 
-  assert(!importedType->getImplicitlyUnwrappedOptionalObjectType());
-
   // Special case AutoreleasingUnsafeMutablePointer<NSError?> parameters.
   auto maybeImportNSErrorPointer = [&]() -> Type {
     if (importKind != ImportTypeKind::Parameter)
@@ -1232,7 +1224,6 @@ static ImportedType adjustTypeForConcreteImport(
   };
 
   if (Type result = maybeImportNSErrorPointer()) {
-    assert(!result->getImplicitlyUnwrappedOptionalObjectType());
     return {result, false};
   }
 
@@ -1278,11 +1269,9 @@ static ImportedType adjustTypeForConcreteImport(
     resultTy = impl.getNamedSwiftTypeSpecialization(impl.getStdlibModule(),
                                                     pointerName,
                                                     resultTy);
-    assert(!resultTy->getImplicitlyUnwrappedOptionalObjectType());
     return resultTy;
   };
   if (Type outParamTy = maybeImportCFOutParameter()) {
-    assert(!outParamTy->getImplicitlyUnwrappedOptionalObjectType());
     importedType = outParamTy;
   }
 
@@ -1381,9 +1370,6 @@ static ImportedType adjustTypeForConcreteImport(
       importedType = OptionalType::get(importedType);
   }
 
-  // We do not expect to return actual IUO types.
-  assert(!importedType->getImplicitlyUnwrappedOptionalObjectType());
-
   return {importedType, isIUO};
 }
 
@@ -1437,10 +1423,6 @@ ImportedType ClangImporter::Implementation::importType(
       *this, type, importResult.AbstractType, importKind, importResult.Hint,
       allowNSUIntegerAsInt, bridging, optionality, resugarNSErrorPointer);
 
-  // We should never get an actual IUO type back.
-  assert(!adjustedType ||
-         !adjustedType.getType()->getImplicitlyUnwrappedOptionalObjectType());
-
   return adjustedType;
 }
 
@@ -1452,9 +1434,6 @@ Type ClangImporter::Implementation::importTypeIgnoreIUO(
   auto importedType = importType(type, importKind, allowNSUIntegerAsInt,
                                  bridging, optionality, resugarNSErrorPointer);
 
-  assert(!importedType ||
-         !importedType.getType()->getImplicitlyUnwrappedOptionalObjectType());
-
   return importedType.getType();
 }
 
@@ -1569,9 +1548,6 @@ ImportedType ClangImporter::Implementation::importFunctionReturnType(
     switch (getClangASTContext().BuiltinInfo.getTypeString(builtinID)[0]) {
     case 'z': // size_t
     case 'Y': // ptrdiff_t
-      assert(!SwiftContext.getIntDecl()
-                  ->getDeclaredType()
-                  ->getImplicitlyUnwrappedOptionalObjectType());
       return {SwiftContext.getIntDecl()->getDeclaredType(), false};
     default:
       break;

lib/ClangImporter/ImporterImpl.h

@@ -639,12 +639,10 @@ class LLVM_LIBRARY_VISIBILITY ClangImporter::Implementation
     }
 #endif
 
-    if (!isIUO) {
-      assert(!ty->getImplicitlyUnwrappedOptionalObjectType());
+    if (!isIUO)
       return;
-    } else {
-      assert(ty->getAnyOptionalObjectType());
-    }
+
+    assert(ty->getOptionalObjectType());
 
     auto *IUOAttr = new (SwiftContext)
         ImplicitlyUnwrappedOptionalAttr(/* implicit= */ true);

lib/IDE/CodeCompletion.cpp

@@ -3158,6 +3158,8 @@ class CompletionLookup final : public swift::VisibleDeclConsumer {
     // FIXME: consider types convertible to T?.
 
     ExprType = ExprType->getRValueType();
+    // FIXME: We don't always pass down whether a type is from an
+    // unforced IUO.
     if (isIUO) {
       if (Type Unwrapped = ExprType->getAnyOptionalObjectType()) {
         lookupVisibleMemberDecls(*this, Unwrapped, CurrDeclContext,
@@ -3184,12 +3186,6 @@ class CompletionLookup final : public swift::VisibleDeclConsumer {
                                    IncludeInstanceMembers);
         }
       }
-    } else if (Type Unwrapped = ExprType->getImplicitlyUnwrappedOptionalObjectType()) {
-      // FIXME: This can go away when IUOs have been removed from the type
-      // system.
-      lookupVisibleMemberDecls(*this, Unwrapped, CurrDeclContext,
-                               TypeResolver.get(),
-                               IncludeInstanceMembers);
     } else {
       return false;
     }

lib/SILGen/SILGenBridging.cpp

@@ -631,13 +631,6 @@ static ManagedValue emitNativeToCBridgedNonoptionalValue(SILGenFunction &SGF,
                                  loweredBridgedTy.castTo<SILFunctionType>());
   }
 
-  // Erase IUO at this point, because there aren't any conformances for
-  // IUO anymore.  Note that the value representation stays the same
-  // because SIL erases the difference.
-  if (auto obj = nativeType->getImplicitlyUnwrappedOptionalObjectType()) {
-    nativeType = OptionalType::get(obj)->getCanonicalType();
-  }
-
   // If the native type conforms to _ObjectiveCBridgeable, use its
   // _bridgeToObjectiveC witness.
   if (auto conformance =