[Property Wrappers] Improve diagnostics for property wrappers initialized out-of-line

include/swift/AST/DiagnosticsSema.def

@@ -5010,6 +5010,12 @@ NOTE(property_wrapper_direct_init,none,
 ERROR(property_wrapper_incompatible_property, none,
       "property type %0 does not match that of the 'wrappedValue' property of "
       "its wrapper type %1", (Type, Type))
+ERROR(wrapped_value_mismatch, none,
+      "property type %0 does not match 'wrappedValue' type %1",
+      (Type, Type))
+ERROR(composed_property_wrapper_mismatch, none,
+      "composed wrapper type %0 does not match former 'wrappedValue' type %1",
+      (Type, Type))
 
 ERROR(property_wrapper_type_access,none,
       "%select{%select{variable|constant}0|property}1 "

lib/Sema/CSApply.cpp

@@ -8039,6 +8039,8 @@ ExprWalker::rewriteTarget(SolutionApplicationTarget target) {
     case swift::CTP_AssignSource:
     case swift::CTP_SubscriptAssignSource:
     case swift::CTP_Condition:
+    case swift::CTP_WrappedProperty:
+    case swift::CTP_ComposedPropertyWrapper:
     case swift::CTP_CannotFail:
       result.setExpr(rewrittenExpr);
       break;
@@ -8139,6 +8141,17 @@ ExprWalker::rewriteTarget(SolutionApplicationTarget target) {
       patternBinding->setInit(index, resultTarget->getAsExpr());
     }
 
+    return target;
+  } else if (auto *wrappedVar = target.getAsUninitializedWrappedVar()) {
+    // Get the outermost wrapper type from the solution
+    auto outermostWrapper = wrappedVar->getAttachedPropertyWrappers().front();
+    auto backingType = solution.simplifyType(
+        solution.getType(outermostWrapper->getTypeRepr()));
+
+    auto &ctx = solution.getConstraintSystem().getASTContext();
+    ctx.setSideCachedPropertyWrapperBackingPropertyType(
+        wrappedVar, backingType->mapTypeOutOfContext());
+
     return target;
   } else {
     auto fn = *target.getAsFunction();
@@ -8419,6 +8432,9 @@ SolutionApplicationTarget SolutionApplicationTarget::walk(ASTWalker &walker) {
 
   case Kind::patternBinding:
     return *this;
+
+  case Kind::uninitializedWrappedVar:
+    return *this;
   }
 
   llvm_unreachable("invalid target kind");

lib/Sema/CSDiagnostics.cpp

@@ -414,7 +414,7 @@ void RequirementFailure::emitRequirementNote(const Decl *anchor, Type lhs,
 }
 
 bool MissingConformanceFailure::diagnoseAsError() {
-  auto *anchor = castToExpr(getAnchor());
+  auto anchor = getAnchor();
   auto nonConformingType = getLHS();
   auto protocolType = getRHS();
 
@@ -423,8 +423,9 @@ bool MissingConformanceFailure::diagnoseAsError() {
   // with it and if so skip conformance error, otherwise we'd
   // produce an unrelated `<type> doesn't conform to Equatable protocol`
   // diagnostic.
-  if (isPatternMatchingOperator(const_cast<Expr *>(anchor))) {
-    if (auto *binaryOp = dyn_cast_or_null<BinaryExpr>(findParentExpr(anchor))) {
+  if (isPatternMatchingOperator(anchor)) {
+    auto *expr = castToExpr(anchor);
+    if (auto *binaryOp = dyn_cast_or_null<BinaryExpr>(findParentExpr(expr))) {
       auto *caseExpr = binaryOp->getArg()->getElement(0);
 
       llvm::SmallPtrSet<Expr *, 4> anchors;
@@ -452,6 +453,7 @@ bool MissingConformanceFailure::diagnoseAsError() {
   // says that conformances for enums with associated values can't be
   // synthesized.
   if (isStandardComparisonOperator(anchor)) {
+    auto *expr = castToExpr(anchor);
     auto isEnumWithAssociatedValues = [](Type type) -> bool {
       if (auto *enumType = type->getAs<EnumType>())
         return !enumType->getDecl()->hasOnlyCasesWithoutAssociatedValues();
@@ -464,7 +466,7 @@ bool MissingConformanceFailure::diagnoseAsError() {
         (protocol->isSpecificProtocol(KnownProtocolKind::Equatable) ||
          protocol->isSpecificProtocol(KnownProtocolKind::Comparable))) {
       if (RequirementFailure::diagnoseAsError()) {
-        auto opName = getOperatorName(anchor);
+        auto opName = getOperatorName(expr);
         emitDiagnostic(diag::no_binary_op_overload_for_enum_with_payload,
                        opName->str());
         return true;
@@ -611,6 +613,10 @@ Optional<Diag<Type, Type>> GenericArgumentsMismatchFailure::getDiagnosticFor(
     return diag::cannot_convert_subscript_assign;
   case CTP_Condition:
     return diag::cannot_convert_condition_value;
+  case CTP_WrappedProperty:
+    return diag::wrapped_value_mismatch;
+  case CTP_ComposedPropertyWrapper:
+    return diag::composed_property_wrapper_mismatch;
 
   case CTP_ThrowStmt:
   case CTP_ForEachStmt:
@@ -2204,6 +2210,8 @@ getContextualNilDiagnostic(ContextualTypePurpose CTP) {
   case CTP_ThrowStmt:
   case CTP_ForEachStmt:
   case CTP_YieldByReference:
+  case CTP_WrappedProperty:
+  case CTP_ComposedPropertyWrapper:
     return None;
 
   case CTP_EnumCaseRawValue:
@@ -2902,6 +2910,11 @@ ContextualFailure::getDiagnosticFor(ContextualTypePurpose context,
   case CTP_Condition:
     return diag::cannot_convert_condition_value;
 
+  case CTP_WrappedProperty:
+    return diag::wrapped_value_mismatch;
+  case CTP_ComposedPropertyWrapper:
+    return diag::composed_property_wrapper_mismatch;
+
   case CTP_ThrowStmt:
   case CTP_ForEachStmt:
   case CTP_Unused:
@@ -4998,8 +5011,15 @@ bool MissingGenericArgumentsFailure::diagnoseAsError() {
         scopedParameters[base].push_back(GP);
       });
 
-  if (!isScoped)
-    return diagnoseForAnchor(castToExpr(getAnchor()), Parameters);
+  // FIXME: this code should be generalized now that we can anchor the
+  // fixes on the TypeRepr with the missing generic arg.
+  if (!isScoped) {
+    assert(getAnchor().is<Expr *>() || getAnchor().is<TypeRepr *>());
+    if (auto *expr = getAsExpr(getAnchor()))
+      return diagnoseForAnchor(expr, Parameters);
+
+    return diagnoseForAnchor(getAnchor().get<TypeRepr *>(), Parameters);
+  }
 
   bool diagnosed = false;
   for (const auto &scope : scopedParameters)

lib/Sema/CSDiagnostics.h

@@ -265,8 +265,9 @@ class RequirementFailure : public FailureDiagnostic {
     assert(getGenericContext() &&
            "Affected decl not within a generic context?");
 
-    if (auto *parentExpr = findParentExpr(getRawAnchor().get<Expr *>()))
-      Apply = dyn_cast<ApplyExpr>(parentExpr);
+    if (auto *expr = getAsExpr(getRawAnchor()))
+      if (auto *parentExpr = findParentExpr(expr))
+        Apply = dyn_cast<ApplyExpr>(parentExpr);
   }
 
   unsigned getRequirementIndex() const {

lib/Sema/CSGen.cpp

@@ -3874,35 +3874,38 @@ static Expr *generateConstraintsFor(ConstraintSystem &cs, Expr *expr,
 /// \param wrappedVar The property that has a property wrapper.
 /// \returns the type of the property.
 static Type generateWrappedPropertyTypeConstraints(
-   ConstraintSystem &cs, Type initializerType,
-   VarDecl *wrappedVar, ConstraintLocator *locator) {
+   ConstraintSystem &cs, Type initializerType, VarDecl *wrappedVar) {
   auto dc = wrappedVar->getInnermostDeclContext();
 
   Type wrapperType = LValueType::get(initializerType);
   Type wrappedValueType;
 
-  for (unsigned i : indices(wrappedVar->getAttachedPropertyWrappers())) {
+  auto wrapperAttributes = wrappedVar->getAttachedPropertyWrappers();
+  for (unsigned i : indices(wrapperAttributes)) {
     Type rawWrapperType = wrappedVar->getAttachedPropertyWrapperType(i);
-    if (!rawWrapperType || rawWrapperType->hasError())
+    auto wrapperInfo = wrappedVar->getAttachedPropertyWrapperTypeInfo(i);
+    if (rawWrapperType->hasError() || !wrapperInfo)
       return Type();
 
     // The former wrappedValue type must be equal to the current wrapper type
     if (wrappedValueType) {
+      auto *typeRepr = wrapperAttributes[i]->getTypeRepr();
+      auto *locator =
+          cs.getConstraintLocator(typeRepr, LocatorPathElt::ContextualType());
       wrapperType = cs.openUnboundGenericTypes(rawWrapperType, locator);
-      cs.addConstraint(ConstraintKind::Equal, wrappedValueType, wrapperType,
+      cs.addConstraint(ConstraintKind::Equal, wrapperType, wrappedValueType,
                        locator);
+      cs.setContextualType(typeRepr, TypeLoc::withoutLoc(wrappedValueType),
+                           CTP_ComposedPropertyWrapper);
     }
 
-    auto wrapperInfo = wrappedVar->getAttachedPropertyWrapperTypeInfo(i);
-    if (!wrapperInfo)
-      return Type();
-
     wrappedValueType = wrapperType->getTypeOfMember(
         dc->getParentModule(), wrapperInfo.valueVar);
   }
 
   // Set up an equality constraint to drop the lvalue-ness of the value
   // type we produced.
+  auto locator = cs.getConstraintLocator(wrappedVar);
   Type propertyType = cs.createTypeVariable(locator, 0);
   cs.addConstraint(ConstraintKind::Equal, propertyType, wrappedValueType, locator);
   return propertyType;
@@ -3922,7 +3925,7 @@ static bool generateInitPatternConstraints(
 
   if (auto wrappedVar = target.getInitializationWrappedVar()) {
     Type propertyType = generateWrappedPropertyTypeConstraints(
-        cs, cs.getType(target.getAsExpr()), wrappedVar, locator);
+        cs, cs.getType(target.getAsExpr()), wrappedVar);
     if (!propertyType)
       return true;
 
@@ -4165,6 +4168,27 @@ bool ConstraintSystem::generateConstraints(
 
     return hadError;
   }
+
+  case SolutionApplicationTarget::Kind::uninitializedWrappedVar: {
+    auto *wrappedVar = target.getAsUninitializedWrappedVar();
+    auto *outermostWrapper = wrappedVar->getAttachedPropertyWrappers().front();
+    auto *typeRepr = outermostWrapper->getTypeRepr();
+    auto backingType = openUnboundGenericTypes(outermostWrapper->getType(),
+                                               getConstraintLocator(typeRepr));
+    setType(typeRepr, backingType);
+
+    auto wrappedValueType =
+        generateWrappedPropertyTypeConstraints(*this, backingType, wrappedVar);
+    Type propertyType = wrappedVar->getType();
+    if (!wrappedValueType || propertyType->hasError())
+      return true;
+
+    addConstraint(ConstraintKind::Equal, propertyType, wrappedValueType,
+        getConstraintLocator(wrappedVar, LocatorPathElt::ContextualType()));
+    setContextualType(wrappedVar, TypeLoc::withoutLoc(wrappedValueType),
+                      CTP_WrappedProperty);
+    return false;
+  }
   }
 }
 

lib/Sema/CSSimplify.cpp

@@ -10156,6 +10156,8 @@ void ConstraintSystem::addContextualConversionConstraint(
   case CTP_CoerceOperand:
   case CTP_SubscriptAssignSource:
   case CTP_ForEachStmt:
+  case CTP_WrappedProperty:
+  case CTP_ComposedPropertyWrapper:
     break;
   }
 

lib/Sema/ConstraintSystem.cpp

@@ -4249,11 +4249,17 @@ Optional<Identifier> constraints::getOperatorName(Expr *expr) {
   return None;
 }
 
-bool constraints::isPatternMatchingOperator(Expr *expr) {
+bool constraints::isPatternMatchingOperator(ASTNode node) {
+  auto *expr = getAsExpr(node);
+  if (!expr) return false;
+
   return isOperator(expr, "~=");
 }
 
-bool constraints::isStandardComparisonOperator(Expr *expr) {
+bool constraints::isStandardComparisonOperator(ASTNode node) {
+  auto *expr = getAsExpr(node);
+  if (!expr) return false;
+
   if (auto opName = getOperatorName(expr)) {
     return opName->is("==") || opName->is("!=") || opName->is("===") ||
            opName->is("!==") || opName->is("<") || opName->is(">") ||
@@ -4674,6 +4680,11 @@ SolutionApplicationTarget SolutionApplicationTarget::forForEachStmt(
   return target;
 }
 
+SolutionApplicationTarget
+SolutionApplicationTarget::forUninitializedWrappedVar(VarDecl *wrappedVar) {
+  return SolutionApplicationTarget(wrappedVar);
+}
+
 ContextualPattern
 SolutionApplicationTarget::getContextualPattern() const {
   assert(kind == Kind::expression);
@@ -4741,6 +4752,8 @@ bool SolutionApplicationTarget::contextualTypeIsOnlyAHint() const {
   case CTP_AssignSource:
   case CTP_SubscriptAssignSource:
   case CTP_Condition:
+  case CTP_WrappedProperty:
+  case CTP_ComposedPropertyWrapper:
   case CTP_CannotFail:
     return false;
   }
@@ -4781,6 +4794,18 @@ void ConstraintSystem::diagnoseFailureFor(SolutionApplicationTarget target) {
     // diagnostic various cases that come up.
     DE.diagnose(expr->getLoc(), diag::type_of_expression_is_ambiguous)
         .highlight(expr->getSourceRange());
+  } else if (auto *wrappedVar = target.getAsUninitializedWrappedVar()) {
+    auto *wrapper = wrappedVar->getAttachedPropertyWrappers().back();
+    Type propertyType = wrappedVar->getInterfaceType();
+    Type wrapperType = wrapper->getType();
+
+    // Emit the property wrapper fallback diagnostic
+    wrappedVar->diagnose(diag::property_wrapper_incompatible_property,
+                         propertyType, wrapperType);
+    if (auto nominal = wrapperType->getAnyNominal()) {
+      nominal->diagnose(diag::property_wrapper_declared_here,
+                        nominal->getName());
+    }
   } else {
     // Emit a poor fallback message.
     DE.diagnose(target.getAsFunction()->getLoc(),