Merge pull request swiftlang#27769 from hborla/anyobject-conformance-failure

[ConstraintSystem] Diagnose missing AnyObject conformance using the MissingConformance constraint fix.

Author: hborla

include/swift/AST/DiagnosticsSema.def

@@ -1727,12 +1727,18 @@ ERROR(type_does_not_conform_owner,none,
 ERROR(type_does_not_conform_in_decl_ref,none,
       "referencing %0 %1 on %2 requires that %3 conform to %4",
       (DescriptiveDeclKind, DeclName, Type, Type, Type))
+ERROR(type_does_not_conform_anyobject_in_decl_ref,none,
+      "referencing %0 %1 on %2 requires that %3 be a class type",
+      (DescriptiveDeclKind, DeclName, Type, Type, Type))
 ERROR(type_does_not_conform_decl_owner,none,
       "%0 %1 requires that %2 conform to %3",
       (DescriptiveDeclKind, DeclName, Type, Type))
-ERROR(type_does_not_conform_in_opaque_return,none,
-      "return type of %0 %1 requires that %2 conform to %3",
+ERROR(type_does_not_conform_anyobject_decl_owner,none,
+      "%0 %1 requires that %2 be a class type",
       (DescriptiveDeclKind, DeclName, Type, Type))
+ERROR(type_does_not_conform_in_opaque_return,none,
+      "return type of %0 %1 requires that %2 %select{conform to %3|be a class type}4",
+      (DescriptiveDeclKind, DeclName, Type, Type, bool))
 ERROR(types_not_equal_decl,none,
       "%0 %1 requires the types %2 and %3 be equivalent",
       (DescriptiveDeclKind, DeclName, Type, Type))
@@ -1751,6 +1757,8 @@ NOTE(where_requirement_failure_both_subst,none,
      "where %0 = %1, %2 = %3", (Type, Type, Type, Type))
 NOTE(requirement_implied_by_conditional_conformance,none,
      "requirement from conditional conformance of %0 to %1", (Type, Type))
+NOTE(wrapped_type_satisfies_requirement,none,
+     "wrapped type %0 satisfies this requirement; did you mean to unwrap?", (Type))
 NOTE(candidate_types_conformance_requirement,none,
      "candidate requires that %0 conform to %1 "
      "(requirement specified as %2 == %3%4)",

lib/Sema/CSDiag.cpp

@@ -651,142 +651,6 @@ bool FailureDiagnosis::diagnoseGeneralOverloadFailure(Constraint *constraint) {
   return true;
 }
 
-static bool
-diagnoseUnresolvedDotExprTypeRequirementFailure(ConstraintSystem &cs,
-                                                Constraint *constraint) {
-  auto &TC = cs.TC;
-
-  auto *locator = constraint->getLocator();
-  if (!locator)
-    return false;
-
-
-  auto reqElt =
-      locator->getLastElementAs<LocatorPathElt::TypeParameterRequirement>();
-  if (!reqElt)
-    return false;
-
-  auto *anchor = locator->getAnchor();
-  if (!anchor)
-    return false;
-
-  auto *UDE = dyn_cast<UnresolvedDotExpr>(anchor);
-  if (!UDE)
-    return false;
-
-  auto ownerType = cs.getType(UDE->getBase());
-  if (!ownerType)
-    return false;
-
-  ownerType = cs.simplifyType(ownerType)->getWithoutSpecifierType();
-  if (ownerType->hasTypeVariable() || ownerType->hasUnresolvedType())
-    return false;
-
-  // If we actually resolved the member to use, use it.
-  auto loc = cs.getConstraintLocator(UDE, ConstraintLocator::Member);
-  auto *member = cs.findResolvedMemberRef(loc);
-  // If the problem is contextual it's diagnosed elsewhere.
-  if (!member || !member->getAsGenericContext())
-    return false;
-
-  auto req = member->getAsGenericContext()
-                 ->getGenericSignature()
-                 ->getRequirements()[reqElt->getIndex()];
-
-  Diag<Type, Type, Type, Type, StringRef> note;
-  switch (req.getKind()) {
-  case RequirementKind::Conformance:
-  case RequirementKind::Layout:
-    return false;
-
-  case RequirementKind::Superclass:
-    note = diag::candidate_types_inheritance_requirement;
-    break;
-
-  case RequirementKind::SameType:
-    note = diag::candidate_types_equal_requirement;
-    break;
-  }
-
-  TC.diagnose(UDE->getLoc(), diag::could_not_find_value_member, ownerType,
-              UDE->getName());
-
-  auto first = cs.simplifyType(constraint->getFirstType());
-  auto second = cs.simplifyType(constraint->getSecondType());
-  auto rawFirstType = req.getFirstType();
-  auto rawSecondType = req.getSecondType();
-
-  TC.diagnose(member, note, first, second, rawFirstType, rawSecondType, "");
-
-  return true;
-}
-
-/// Diagnose problems related to failures in constraints
-/// generated by `openGeneric` which represent different
-/// kinds of type parameter requirements.
-static bool diagnoseTypeRequirementFailure(ConstraintSystem &cs,
-                                           Constraint *constraint) {
-  auto &TC = cs.TC;
-
-  auto *locator = constraint->getLocator();
-  if (!locator)
-    return false;
-
-  auto path = locator->getPath();
-  if (path.empty())
-    return false;
-
-  auto &last = path.back();
-  if (last.getKind() != ConstraintLocator::TypeParameterRequirement)
-    return false;
-
-  auto *anchor = locator->getAnchor();
-  if (!anchor)
-    return false;
-
-  auto ownerType = cs.getType(anchor);
-
-  if (isa<UnresolvedMemberExpr>(anchor))
-    ownerType = cs.getContextualType();
-  else if (auto *UDE = dyn_cast<UnresolvedDotExpr>(anchor))
-    ownerType = cs.getType(UDE->getBase());
-
-  if (!ownerType)
-    return false;
-
-  ownerType = cs.simplifyType(ownerType)->getWithoutSpecifierType();
-  if (ownerType->hasTypeVariable() || ownerType->hasUnresolvedType())
-    return false;
-
-  if (diagnoseUnresolvedDotExprTypeRequirementFailure(cs, constraint))
-    return true;
-
-  auto lhs = cs.simplifyType(constraint->getFirstType());
-  auto rhs = cs.simplifyType(constraint->getSecondType());
-
-  switch (constraint->getKind()) {
-  case ConstraintKind::ConformsTo:
-    TC.diagnose(anchor->getLoc(), diag::type_does_not_conform_owner, ownerType,
-                lhs, rhs);
-    return true;
-
-  case ConstraintKind::Subtype: // superclass
-    TC.diagnose(anchor->getLoc(), diag::type_does_not_inherit, ownerType, lhs,
-                rhs);
-    return true;
-
-  case ConstraintKind::Bind: { // same type
-    TC.diagnose(anchor->getLoc(), diag::types_not_equal, ownerType, lhs, rhs);
-    return true;
-  }
-
-  default:
-    break;
-  }
-
-  return false;
-}
-
 bool FailureDiagnosis::diagnoseGeneralConversionFailure(Constraint *constraint){
   auto anchor = expr;
   bool resolvedAnchorToExpr = false;
@@ -964,9 +828,6 @@ bool FailureDiagnosis::diagnoseGeneralConversionFailure(Constraint *constraint){
     }
   }
 
-  if (diagnoseTypeRequirementFailure(CS, constraint))
-    return true;
-
   diagnose(anchor->getLoc(), diag::types_not_convertible,
            constraint->getKind() == ConstraintKind::Subtype,
            fromType, toType)

lib/Sema/CSDiagnostics.cpp

@@ -478,7 +478,8 @@ bool RequirementFailure::diagnoseAsError() {
     auto *namingDecl = OTD->getNamingDecl();
     emitDiagnostic(
         anchor->getLoc(), diag::type_does_not_conform_in_opaque_return,
-        namingDecl->getDescriptiveKind(), namingDecl->getFullName(), lhs, rhs);
+        namingDecl->getDescriptiveKind(), namingDecl->getFullName(), lhs, rhs,
+        rhs->isAnyObject());
 
     if (auto *repr = namingDecl->getOpaqueResultTypeRepr()) {
       emitDiagnostic(repr->getLoc(), diag::opaque_return_type_declared_here)
@@ -517,14 +518,27 @@ void RequirementFailure::emitRequirementNote(const Decl *anchor, Type lhs,
                                              Type rhs) const {
   auto &req = getRequirement();
 
+  if (req.getKind() != RequirementKind::SameType) {
+    if (auto wrappedType = lhs->getOptionalObjectType()) {
+      auto &tc = getTypeChecker();
+      auto kind = (req.getKind() == RequirementKind::Superclass ?
+                   ConstraintKind::Subtype : ConstraintKind::ConformsTo);
+      if (tc.typesSatisfyConstraint(wrappedType, rhs, /*openArchetypes=*/false,
+                                    kind, getDC()))
+        emitDiagnostic(getAnchor()->getLoc(),
+                       diag::wrapped_type_satisfies_requirement, wrappedType);
+    }
+  }
+
   if (isConditional()) {
     emitDiagnostic(anchor, diag::requirement_implied_by_conditional_conformance,
                    resolveType(Conformance->getType()),
                    Conformance->getProtocol()->getDeclaredInterfaceType());
     return;
   }
 
-  if (rhs->isEqual(req.getSecondType())) {
+  if (req.getKind() == RequirementKind::Layout ||
+      rhs->isEqual(req.getSecondType())) {
     emitDiagnostic(anchor, diag::where_requirement_failure_one_subst,
                    req.getFirstType(), lhs);
     return;
@@ -589,7 +603,8 @@ bool MissingConformanceFailure::diagnoseAsError() {
 
 bool MissingConformanceFailure::diagnoseTypeCannotConform(Expr *anchor,
     Type nonConformingType, Type protocolType) const {
-  if (!(nonConformingType->is<AnyFunctionType>() ||
+  if (getRequirement().getKind() == RequirementKind::Layout ||
+      !(nonConformingType->is<AnyFunctionType>() ||
       nonConformingType->is<TupleType>() ||
       nonConformingType->isExistentialType() ||
       nonConformingType->is<AnyMetatypeType>())) {

lib/Sema/CSDiagnostics.h

@@ -320,8 +320,8 @@ class RequirementFailure : public FailureDiagnostic {
   Type LHS, RHS;
 
 public:
-  RequirementFailure(ConstraintSystem &cs, Expr *expr, RequirementKind kind,
-                     Type lhs, Type rhs, ConstraintLocator *locator)
+  RequirementFailure(ConstraintSystem &cs, Expr *expr, Type lhs, Type rhs,
+                     ConstraintLocator *locator)
       : FailureDiagnostic(expr, cs, locator),
         Conformance(getConformanceForConditionalReq(locator)),
         Signature(getSignature(locator)), AffectedDecl(getDeclRef()),
@@ -334,9 +334,6 @@ class RequirementFailure : public FailureDiagnostic {
     assert(getGenericContext() &&
            "Affected decl not within a generic context?");
 
-    auto reqElt = locator->castLastElementTo<LocatorPathElt::AnyRequirement>();
-    assert(reqElt.getRequirementKind() == kind);
-
     // It's possible sometimes not to have no base expression.
     if (!expr)
       return;
@@ -418,8 +415,12 @@ class MissingConformanceFailure final : public RequirementFailure {
   MissingConformanceFailure(Expr *expr, ConstraintSystem &cs,
                             ConstraintLocator *locator,
                             std::pair<Type, Type> conformance)
-      : RequirementFailure(cs, expr, RequirementKind::Conformance,
-                           conformance.first, conformance.second, locator) {}
+      : RequirementFailure(cs, expr, conformance.first, conformance.second,
+                           locator) {
+    auto reqElt = locator->castLastElementTo<LocatorPathElt::AnyRequirement>();
+    assert(reqElt.getRequirementKind() == RequirementKind::Conformance ||
+           reqElt.getRequirementKind() == RequirementKind::Layout);
+  }
 
   bool diagnoseAsError() override;
 
@@ -433,11 +434,15 @@ class MissingConformanceFailure final : public RequirementFailure {
   bool diagnoseAsAmbiguousOperatorRef();
 
   DiagOnDecl getDiagnosticOnDecl() const override {
-    return diag::type_does_not_conform_decl_owner;
+    return (getRequirement().getKind() == RequirementKind::Layout ?
+            diag::type_does_not_conform_anyobject_decl_owner :
+            diag::type_does_not_conform_decl_owner);
   }
 
   DiagInReference getDiagnosticInRereference() const override {
-    return diag::type_does_not_conform_in_decl_ref;
+    return (getRequirement().getKind() == RequirementKind::Layout ?
+            diag::type_does_not_conform_anyobject_in_decl_ref :
+            diag::type_does_not_conform_in_decl_ref);
   }
 
   DiagAsNote getDiagnosticAsNote() const override {
@@ -468,8 +473,10 @@ class SameTypeRequirementFailure final : public RequirementFailure {
 public:
   SameTypeRequirementFailure(Expr *expr, ConstraintSystem &cs, Type lhs,
                              Type rhs, ConstraintLocator *locator)
-      : RequirementFailure(cs, expr, RequirementKind::SameType, lhs, rhs,
-                           locator) {}
+      : RequirementFailure(cs, expr, lhs, rhs, locator) {
+    auto reqElt = locator->castLastElementTo<LocatorPathElt::AnyRequirement>();
+    assert(reqElt.getRequirementKind() == RequirementKind::SameType);
+  }
 
 protected:
   DiagOnDecl getDiagnosticOnDecl() const override {
@@ -502,8 +509,10 @@ class SuperclassRequirementFailure final : public RequirementFailure {
 public:
   SuperclassRequirementFailure(Expr *expr, ConstraintSystem &cs, Type lhs,
                                Type rhs, ConstraintLocator *locator)
-      : RequirementFailure(cs, expr, RequirementKind::Superclass, lhs, rhs,
-                           locator) {}
+      : RequirementFailure(cs, expr, lhs, rhs, locator) {
+    auto reqElt = locator->castLastElementTo<LocatorPathElt::AnyRequirement>();
+    assert(reqElt.getRequirementKind() == RequirementKind::Superclass);
+  }
 
 protected:
   DiagOnDecl getDiagnosticOnDecl() const override {

lib/Sema/CSSimplify.cpp

@@ -2015,6 +2015,12 @@ ConstraintSystem::matchExistentialTypes(Type type1, Type type2,
               if (req &&
                   req->getRequirementKind() == RequirementKind::Superclass)
                 return getTypeMatchSuccess();
+
+              auto *fix = fixRequirementFailure(*this, type1, type2, locator);
+              if (fix && !recordFix(fix)) {
+                recordFixedRequirement(type1, RequirementKind::Layout, type2);
+                return getTypeMatchSuccess();
+              }
             }
           }
 
@@ -3437,8 +3443,10 @@ ConstraintSystem::matchTypes(Type type1, Type type2, ConstraintKind kind,
       if (shouldAttemptFixes()) {
         auto last = locator.last();
         // If this happens as part of the argument-to-parameter
-        // conversion, there is a tailored fix/diagnostic.
-        if (last && last->is<LocatorPathElt::ApplyArgToParam>())
+        // conversion or type requirement, there is a tailored
+        // fix/diagnostic.
+        if (last && (last->is<LocatorPathElt::ApplyArgToParam>() ||
+                     last->is<LocatorPathElt::AnyRequirement>()))
           break;
       }
       // If two module types or archetypes were not already equal, there's
@@ -4339,24 +4347,6 @@ ConstraintSystem::SolutionKind ConstraintSystem::simplifyConformsToConstraint(
   if (!shouldAttemptFixes())
     return SolutionKind::Error;
 
-  // See if there's anything we can do to fix the conformance:
-  if (auto optionalObjectType = type->getOptionalObjectType()) {
-    TypeMatchOptions subflags = getDefaultDecompositionOptions(flags);
-    // The underlying type of an optional may conform to the protocol if the
-    // optional doesn't; suggest forcing if that's the case.
-    auto result = simplifyConformsToConstraint(
-        optionalObjectType, protocol, kind,
-        locator.withPathElement(LocatorPathElt::GenericArgument(0)), subflags);
-    if (result == SolutionKind::Solved) {
-      auto *fix = ForceOptional::create(*this, type, optionalObjectType,
-                                        getConstraintLocator(locator));
-      if (recordFix(fix)) {
-        return SolutionKind::Error;
-      }
-    }
-    return result;
-  }
-
   auto protocolTy = protocol->getDeclaredType();
   // If this conformance has been fixed already, let's just consider this done.
   if (hasFixedRequirement(type, RequirementKind::Conformance, protocolTy))

test/APINotes/versioned-objc.swift

@@ -16,7 +16,7 @@ class ProtoWithVersionedUnavailableMemberImpl: ProtoWithVersionedUnavailableMemb
 func testNonGeneric() {
   // CHECK-DIAGS-4:[[@LINE+1]]:{{[0-9]+}}: error: cannot convert value of type 'Any' to specified type 'Int'
   let _: Int = NewlyGenericSub.defaultElement()
-  // CHECK-DIAGS-5:[[@LINE-1]]:{{[0-9]+}}: error: generic parameter 'Element' could not be inferred
+  // CHECK-DIAGS-5:[[@LINE-1]]:{{[0-9]+}}: error: generic class 'NewlyGenericSub' requires that 'Int' be a class type
 
   // CHECK-DIAGS-4:[[@LINE+1]]:{{[0-9]+}}: error: cannot specialize non-generic type 'NewlyGenericSub'
   let _: Int = NewlyGenericSub<Base>.defaultElement()