Merge pull request swiftlang#78272 from xedin/rdar-140300022-6.1

[6.1][TypeChecker/SILGen] Allow `any Sendable` to match `Any` while matching generic arguments

Author: xedin

include/swift/AST/DiagnosticsSema.def

@@ -2789,6 +2789,9 @@ ERROR(types_not_inherited_decl,none,
 ERROR(types_not_inherited_in_decl_ref,none,
       "referencing %kind0 on %1 requires that %2 inherit from %3",
       (const ValueDecl *, Type, Type, Type))
+ERROR(cannot_reference_conditional_member_on_base_multiple_mismatches,none,
+      "cannot reference %kind0 on %1",
+      (const ValueDecl *, Type))
 NOTE(where_requirement_failure_one_subst,none,
      "where %0 = %1", (Type, Type))
 NOTE(where_requirement_failure_both_subst,none,

include/swift/AST/Expr.h

@@ -3615,6 +3615,24 @@ class ActorIsolationErasureExpr : public ImplicitConversionExpr {
   }
 };
 
+/// UnsafeCastExpr - A special kind of conversion that performs an unsafe
+/// bitcast from one type to the other.
+///
+/// Note that this is an unsafe operation and type-checker is allowed to
+/// use this only in a limited number of cases like: `any Sendable` -> `Any`
+/// conversions in some positions, covariant conversions of function and
+/// function result types.
+class UnsafeCastExpr : public ImplicitConversionExpr {
+public:
+  UnsafeCastExpr(Expr *subExpr, Type type)
+      : ImplicitConversionExpr(ExprKind::UnsafeCast, subExpr, type) {
+  }
+
+  static bool classof(const Expr *E) {
+    return E->getKind() == ExprKind::UnsafeCast;
+  }
+};
+
 /// Extracts the isolation of a dynamically isolated function value.
 class ExtractFunctionIsolationExpr : public Expr {
   /// The function value expression from which to extract the

include/swift/AST/ExprNodes.def

@@ -191,7 +191,8 @@ ABSTRACT_EXPR(ImplicitConversion, Expr)
   EXPR(LinearFunctionExtractOriginal, ImplicitConversionExpr)
   EXPR(LinearToDifferentiableFunction, ImplicitConversionExpr)
   EXPR(ActorIsolationErasure, ImplicitConversionExpr)
-  EXPR_RANGE(ImplicitConversion, Load, ActorIsolationErasure)
+  EXPR(UnsafeCast, ImplicitConversionExpr)
+  EXPR_RANGE(ImplicitConversion, Load, UnsafeCast)
 ABSTRACT_EXPR(ExplicitCast, Expr)
   ABSTRACT_EXPR(CheckedCast, ExplicitCastExpr)
     EXPR(ForcedCheckedCast, CheckedCastExpr)

include/swift/AST/Types.h

@@ -674,6 +674,9 @@ class alignas(1 << TypeAlignInBits) TypeBase
   /// Is this an existential containing only marker protocols?
   bool isMarkerExistential();
 
+  /// Is this `any Sendable` type?
+  bool isSendableExistential();
+
   bool isPlaceholder();
 
   /// Returns true if this contextual type does not satisfy a conformance to

lib/AST/ASTDumper.cpp

@@ -2727,6 +2727,12 @@ class PrintExpr : public ExprVisitor<PrintExpr, void, StringRef>,
     printFoot();
   }
 
+  void visitUnsafeCastExpr(UnsafeCastExpr *E, StringRef label) {
+    printCommon(E, "unsafe_cast_expr", label);
+    printRec(E->getSubExpr());
+    printFoot();
+  }
+
   void visitExtractFunctionIsolationExpr(ExtractFunctionIsolationExpr *E,
                                          StringRef label) {
     printCommon(E, "extract_function_isolation", label);

lib/AST/ASTPrinter.cpp

@@ -5346,6 +5346,9 @@ void PrintAST::visitLinearToDifferentiableFunctionExpr(swift::LinearToDifferenti
 void PrintAST::visitActorIsolationErasureExpr(ActorIsolationErasureExpr *expr) {
 }
 
+void PrintAST::visitUnsafeCastExpr(UnsafeCastExpr *expr) {
+}
+
 void PrintAST::visitExtractFunctionIsolationExpr(ExtractFunctionIsolationExpr *expr) {
   visit(expr->getFunctionExpr());
   Printer << ".isolation";

lib/AST/Expr.cpp

@@ -459,6 +459,7 @@ ConcreteDeclRef Expr::getReferencedDecl(bool stopAtParenExpr) const {
   PASS_THROUGH_REFERENCE(UnderlyingToOpaque, getSubExpr);
   PASS_THROUGH_REFERENCE(Unreachable, getSubExpr);
   PASS_THROUGH_REFERENCE(ActorIsolationErasure, getSubExpr);
+  PASS_THROUGH_REFERENCE(UnsafeCast, getSubExpr);
   NO_REFERENCE(Coerce);
   NO_REFERENCE(ForcedCheckedCast);
   NO_REFERENCE(ConditionalCheckedCast);
@@ -828,6 +829,7 @@ bool Expr::canAppendPostfixExpression(bool appendingPostfixOperator) const {
   case ExprKind::UnderlyingToOpaque:
   case ExprKind::Unreachable:
   case ExprKind::ActorIsolationErasure:
+  case ExprKind::UnsafeCast:
   case ExprKind::TypeValue:
     // Implicit conversion nodes have no syntax of their own; defer to the
     // subexpression.
@@ -1058,6 +1060,7 @@ bool Expr::isValidParentOfTypeExpr(Expr *typeExpr) const {
   case ExprKind::CurrentContextIsolation:
   case ExprKind::ActorIsolationErasure:
   case ExprKind::ExtractFunctionIsolation:
+  case ExprKind::UnsafeCast:
     return false;
   }
 

lib/AST/Type.cpp

@@ -163,6 +163,17 @@ bool TypeBase::isMarkerExistential() {
   return true;
 }
 
+bool TypeBase::isSendableExistential() {
+  Type constraint = this;
+  if (auto existential = constraint->getAs<ExistentialType>())
+    constraint = existential->getConstraintType();
+
+  if (!constraint->isConstraintType())
+    return false;
+
+  return constraint->getKnownProtocol() == KnownProtocolKind::Sendable;
+}
+
 bool TypeBase::isPlaceholder() {
   return is<PlaceholderType>();
 }

lib/SILGen/SILGenBuilder.cpp

@@ -757,6 +757,31 @@ ManagedValue SILGenBuilder::createUncheckedBitCast(SILLocation loc,
   return cloner.clone(cast);
 }
 
+ManagedValue SILGenBuilder::createUncheckedForwardingCast(SILLocation loc,
+                                                          ManagedValue value,
+                                                          SILType type) {
+  CleanupCloner cloner(*this, value);
+  SILValue cast = createUncheckedForwardingCast(loc, value.getValue(), type);
+  
+  // Currently createUncheckedBitCast only produces these
+  // instructions. We assert here to make sure if this changes, this code is
+  // updated.
+  assert((isa<UncheckedTrivialBitCastInst>(cast) ||
+          isa<UncheckedRefCastInst>(cast) ||
+          isa<UncheckedValueCastInst>(cast) ||
+          isa<ConvertFunctionInst>(cast)) &&
+         "SILGenBuilder is out of sync with SILBuilder.");
+
+  // If we have a trivial inst, just return early.
+  if (isa<UncheckedTrivialBitCastInst>(cast))
+    return ManagedValue::forObjectRValueWithoutOwnership(cast);
+
+  // Otherwise, we forward the cleanup of the input value and place the cleanup
+  // on the cast value since unchecked_ref_cast is "forwarding".
+  value.forward(SGF);
+  return cloner.clone(cast);
+}
+
 ManagedValue SILGenBuilder::createOpenExistentialRef(SILLocation loc,
                                                      ManagedValue original,
                                                      SILType type) {

lib/SILGen/SILGenBuilder.h

@@ -340,6 +340,11 @@ class SILGenBuilder : public SILBuilder {
   ManagedValue createUncheckedBitCast(SILLocation loc, ManagedValue original,
                                       SILType type);
 
+  using SILBuilder::createUncheckedForwardingCast;
+  ManagedValue createUncheckedForwardingCast(SILLocation loc,
+                                             ManagedValue original,
+                                             SILType type);
+
   using SILBuilder::createOpenExistentialRef;
   ManagedValue createOpenExistentialRef(SILLocation loc, ManagedValue arg,
                                         SILType openedType);

lib/SILGen/SILGenExpr.cpp

@@ -497,6 +497,7 @@ namespace {
     RValue visitCovariantReturnConversionExpr(
              CovariantReturnConversionExpr *E,
              SGFContext C);
+    RValue visitUnsafeCastExpr(UnsafeCastExpr *E, SGFContext C);
     RValue visitErasureExpr(ErasureExpr *E, SGFContext C);
     RValue visitAnyHashableErasureExpr(AnyHashableErasureExpr *E, SGFContext C);
     RValue visitForcedCheckedCastExpr(ForcedCheckedCastExpr *E,
@@ -2132,6 +2133,24 @@ RValue RValueEmitter::visitExtractFunctionIsolationExpr(
   return RValue(SGF, E, result);
 }
 
+RValue RValueEmitter::visitUnsafeCastExpr(UnsafeCastExpr *E, SGFContext C) {
+  ManagedValue original = SGF.emitRValueAsSingleValue(E->getSubExpr());
+  SILType resultType = SGF.getLoweredType(E->getType());
+
+  if (resultType == original.getType())
+    return RValue(SGF, E, original);
+
+  ManagedValue result;
+  if (original.getType().isAddress()) {
+    ASSERT(resultType.isAddress());
+    result = SGF.B.createUncheckedAddrCast(E, original, resultType);
+  } else {
+    result = SGF.B.createUncheckedForwardingCast(E, original, resultType);
+  }
+
+  return RValue(SGF, E, result);
+}
+
 RValue RValueEmitter::visitErasureExpr(ErasureExpr *E, SGFContext C) {
   if (auto result = tryEmitAsBridgingConversion(SGF, E, false, C)) {
     return RValue(SGF, E, *result);

lib/Sema/CSApply.cpp

@@ -7066,6 +7066,18 @@ Expr *ExprRewriter::coerceToType(Expr *expr, Type toType,
         }
       }
 
+      // `any Sendable` -> `Any` conversion is allowed in generic
+      // argument positions.
+      {
+        auto erasedFromType = fromType->stripConcurrency(
+            /*recursive=*/true, /*dropGlobalActor=*/false);
+        auto erasedToType = toType->stripConcurrency(
+            /*recursive=*/true, /*dropGlobalActor=*/false);
+
+        if (erasedFromType->isEqual(erasedToType))
+          return cs.cacheType(new (ctx) UnsafeCastExpr(expr, toType));
+      }
+
       auto &err = llvm::errs();
       err << "fromType->getCanonicalType() = ";
       fromType->getCanonicalType()->dump(err);

lib/Sema/CSDiagnostics.cpp

@@ -904,16 +904,44 @@ bool GenericArgumentsMismatchFailure::diagnoseAsError() {
   // before pointer types could be compared.
   auto locator = getLocator();
   auto path = locator->getPath();
-  unsigned toDrop = 0;
-  for (const auto &elt : llvm::reverse(path)) {
-    if (!elt.is<LocatorPathElt::OptionalPayload>())
-      break;
 
-    // Disregard optional payload element to look at its source.
-    ++toDrop;
+  // If there are generic types involved, we need to find
+  // the outermost generic types and report on them instead
+  // of their arguments.
+  // For example:
+  //
+  //    <expr> -> contextual type
+  //           -> generic type S<[Int]>
+  //           -> generic type S<[String]>
+  //           -> generic argument #0
+  //
+  // Is going to have from/to types as `[Int]` and `[String]` but
+  // the diagnostic should mention `S<[Int]>` and `S<[String]>`
+  // because it refers to a contextual type location.
+  if (locator->isLastElement<LocatorPathElt::GenericArgument>()) {
+    for (unsigned i = 0; i < path.size(); ++i) {
+      if (auto genericType = path[i].getAs<LocatorPathElt::GenericType>()) {
+        ASSERT(i + 1 < path.size());
+
+        fromType = resolveType(genericType->getType());
+        toType = resolveType(
+            path[i + 1].castTo<LocatorPathElt::GenericType>().getType());
+        break;
+      }
+    }
   }
 
-  path = path.drop_back(toDrop);
+  while (!path.empty()) {
+    auto last = path.back();
+    if (last.is<LocatorPathElt::OptionalPayload>() ||
+        last.is<LocatorPathElt::GenericType>() ||
+        last.is<LocatorPathElt::GenericArgument>()) {
+      path = path.drop_back();
+      continue;
+    }
+
+    break;
+  }
 
   std::optional<Diag<Type, Type>> diagnostic;
   if (path.empty()) {
@@ -1009,6 +1037,34 @@ bool GenericArgumentsMismatchFailure::diagnoseAsError() {
       break;
     }
 
+    case ConstraintLocator::Member: {
+      auto *memberLoc = getConstraintLocator(anchor, path);
+      auto selectedOverload = getOverloadChoiceIfAvailable(memberLoc);
+      if (!selectedOverload)
+        return false;
+
+      auto baseTy = selectedOverload->choice.getBaseType()->getRValueType();
+      auto *memberRef = selectedOverload->choice.getDecl();
+
+      if (Mismatches.size() == 1) {
+        auto mismatchIdx = Mismatches.front();
+        auto actualArgTy = getActual()->getGenericArgs()[mismatchIdx];
+        auto requiredArgTy = getRequired()->getGenericArgs()[mismatchIdx];
+
+        emitDiagnostic(diag::types_not_equal_in_decl_ref, memberRef, baseTy,
+                       actualArgTy, requiredArgTy);
+        emitDiagnosticAt(memberRef, diag::decl_declared_here, memberRef);
+        return true;
+      }
+
+      emitDiagnostic(
+          diag::cannot_reference_conditional_member_on_base_multiple_mismatches,
+          memberRef, baseTy);
+      emitDiagnosticAt(memberRef, diag::decl_declared_here, memberRef);
+      emitNotesForMismatches();
+      return true;
+    }
+
     default:
       break;
     }