Embedded: Distinguish @_unavailableInEmbedded from @availble(*, unavailable)

include/swift/AST/Attr.h

@@ -147,6 +147,14 @@ class DeclAttribute : public AttributeBase {
       Value : 32
     );
 
+    SWIFT_INLINE_BITFIELD(AvailableAttr, DeclAttribute, 1+1,
+      /// Whether this attribute was spelled `@_spi_available`.
+      IsSPI : 1,
+
+      /// Whether this attribute was spelled `@_unavailableInEmbedded`.
+      IsForEmbedded : 1
+    );
+
     SWIFT_INLINE_BITFIELD(ClangImporterSynthesizedTypeAttr, DeclAttribute, 1,
       kind : 1
     );
@@ -674,8 +682,6 @@ enum class PlatformAgnosticAvailabilityKind {
 /// Defines the @available attribute.
 class AvailableAttr : public DeclAttribute {
 public:
-#define INIT_VER_TUPLE(X) X(X.empty() ? std::optional<llvm::VersionTuple>() : X)
-
   AvailableAttr(SourceLoc AtLoc, SourceRange Range, PlatformKind Platform,
                 StringRef Message, StringRef Rename, ValueDecl *RenameDecl,
                 const llvm::VersionTuple &Introduced,
@@ -684,15 +690,7 @@ class AvailableAttr : public DeclAttribute {
                 SourceRange DeprecatedRange,
                 const llvm::VersionTuple &Obsoleted, SourceRange ObsoletedRange,
                 PlatformAgnosticAvailabilityKind PlatformAgnostic,
-                bool Implicit, bool IsSPI)
-      : DeclAttribute(DeclAttrKind::Available, AtLoc, Range, Implicit),
-        Message(Message), Rename(Rename), RenameDecl(RenameDecl),
-        INIT_VER_TUPLE(Introduced), IntroducedRange(IntroducedRange),
-        INIT_VER_TUPLE(Deprecated), DeprecatedRange(DeprecatedRange),
-        INIT_VER_TUPLE(Obsoleted), ObsoletedRange(ObsoletedRange),
-        PlatformAgnostic(PlatformAgnostic), Platform(Platform), IsSPI(IsSPI) {}
-
-#undef INIT_VER_TUPLE
+                bool Implicit, bool IsSPI, bool IsForEmbedded = false);
 
   /// The optional message.
   const StringRef Message;
@@ -735,9 +733,6 @@ class AvailableAttr : public DeclAttribute {
   /// The platform of the availability.
   const PlatformKind Platform;
 
-  /// Whether this is available as SPI.
-  const bool IsSPI;
-
   /// Whether this is a language-version-specific entity.
   bool isLanguageVersionSpecific() const;
 
@@ -753,6 +748,12 @@ class AvailableAttr : public DeclAttribute {
   /// Whether this is a noasync attribute.
   bool isNoAsync() const;
 
+  /// Whether this attribute was spelled `@_spi_available`.
+  bool isSPI() const { return Bits.AvailableAttr.IsSPI; }
+
+  /// Whether this attribute was spelled `@_unavailableInEmbedded`.
+  bool isForEmbedded() const { return Bits.AvailableAttr.IsForEmbedded; }
+
   /// Returns the platform-agnostic availability.
   PlatformAgnosticAvailabilityKind getPlatformAgnosticAvailability() const {
     return PlatformAgnostic;

include/swift/Strings.h

@@ -85,6 +85,10 @@ constexpr static const StringLiteral CLANG_MODULE_DEFAULT_SPI_GROUP_NAME =
 constexpr static const StringLiteral SPI_AVAILABLE_ATTRNAME =
   "_spi_available";
 
+/// The attribute name for @_unavailableInEmbedded
+constexpr static const StringLiteral UNAVAILABLE_IN_EMBEDDED_ATTRNAME =
+    "_unavailableInEmbedded";
+
 /// A composition class containing a StringLiteral for the names of
 /// Swift builtins. The reason we use this is to ensure that we when
 /// necessary slice off the "Builtin." prefix from these names in a

lib/AST/Attr.cpp

@@ -662,7 +662,7 @@ static bool isShortAvailable(const DeclAttribute *DA) {
   if (!AvailAttr)
     return false;
 
-  if (AvailAttr->IsSPI)
+  if (AvailAttr->isSPI())
     return false;
 
   if (!AvailAttr->Introduced.has_value())
@@ -1371,7 +1371,7 @@ bool DeclAttribute::printImpl(ASTPrinter &Printer, const PrintOptions &Options,
     auto Attr = cast<AvailableAttr>(this);
     if (Options.SuppressNoAsyncAvailabilityAttr && Attr->isNoAsync())
       return false;
-    if (Options.printPublicInterface() && Attr->IsSPI) {
+    if (Options.printPublicInterface() && Attr->isSPI()) {
       assert(Attr->hasPlatform());
       assert(Attr->Introduced.has_value());
       Printer.printAttrName("@available");
@@ -1380,7 +1380,14 @@ bool DeclAttribute::printImpl(ASTPrinter &Printer, const PrintOptions &Options,
       Printer << ", unavailable)";
       break;
     }
-    if (Attr->IsSPI) {
+    if (Attr->isForEmbedded()) {
+      std::string atUnavailableInEmbedded =
+          (llvm::Twine("@") + UNAVAILABLE_IN_EMBEDDED_ATTRNAME).str();
+      Printer.printAttrName(atUnavailableInEmbedded);
+      break;
+    }
+
+    if (Attr->isSPI()) {
       std::string atSPI = (llvm::Twine("@") + SPI_AVAILABLE_ATTRNAME).str();
       Printer.printAttrName(atSPI);
     } else {
@@ -2243,6 +2250,34 @@ Type RawLayoutAttr::getResolvedCountType(StructDecl *sd) const {
                            ErrorType::get(ctx));
 }
 
+#define INIT_VER_TUPLE(X) X(X.empty() ? std::optional<llvm::VersionTuple>() : X)
+
+AvailableAttr::AvailableAttr(
+    SourceLoc AtLoc, SourceRange Range, PlatformKind Platform,
+    StringRef Message, StringRef Rename, ValueDecl *RenameDecl,
+    const llvm::VersionTuple &Introduced, SourceRange IntroducedRange,
+    const llvm::VersionTuple &Deprecated, SourceRange DeprecatedRange,
+    const llvm::VersionTuple &Obsoleted, SourceRange ObsoletedRange,
+    PlatformAgnosticAvailabilityKind PlatformAgnostic, bool Implicit,
+    bool IsSPI, bool IsForEmbedded)
+    : DeclAttribute(DeclAttrKind::Available, AtLoc, Range, Implicit),
+      Message(Message), Rename(Rename), RenameDecl(RenameDecl),
+      INIT_VER_TUPLE(Introduced), IntroducedRange(IntroducedRange),
+      INIT_VER_TUPLE(Deprecated), DeprecatedRange(DeprecatedRange),
+      INIT_VER_TUPLE(Obsoleted), ObsoletedRange(ObsoletedRange),
+      PlatformAgnostic(PlatformAgnostic), Platform(Platform) {
+  Bits.AvailableAttr.IsSPI = IsSPI;
+
+  if (IsForEmbedded) {
+    // FIXME: The IsForEmbedded bit should be removed when library availability
+    // conditions are implemented (rdar://138802876)
+    Bits.AvailableAttr.IsForEmbedded = true;
+    assert(Platform == PlatformKind::none);
+  }
+}
+
+#undef INIT_VER_TUPLE
+
 AvailableAttr *
 AvailableAttr::createPlatformAgnostic(ASTContext &C,
                                    StringRef Message,
@@ -2294,7 +2329,8 @@ AvailableAttr *AvailableAttr::clone(ASTContext &C, bool implicit) const {
                                implicit ? SourceRange() : ObsoletedRange,
                                PlatformAgnostic,
                                implicit,
-                               IsSPI);
+                               isSPI(),
+                               isForEmbedded());
 }
 
 std::optional<OriginallyDefinedInAttr::ActiveVersion>

lib/AST/Availability.cpp

@@ -114,7 +114,7 @@ static void mergeWithInferredAvailability(const AvailableAttr *Attr,
 
   // The merge of two introduction versions is the maximum of the two versions.
   if (mergeIntoInferredVersion(Attr->Introduced, Inferred.Introduced, std::max)) {
-    Inferred.IsSPI = Attr->IsSPI;
+    Inferred.IsSPI = Attr->isSPI();
   }
 
   // The merge of deprecated and obsoleted versions takes the minimum.
@@ -596,7 +596,7 @@ AvailabilityRange AvailabilityInference::availableRange(const Decl *D) {
 
 bool AvailabilityInference::isAvailableAsSPI(const Decl *D) {
   if (auto attr = attrForAvailableRange(D))
-    return attr->IsSPI;
+    return attr->isSPI();
 
   return false;
 }

lib/Parse/ParseDecl.cpp

@@ -4501,18 +4501,16 @@ ParserStatus Parser::parseDeclAttribute(DeclAttributes &Attributes,
 
   // Rewrite @_unavailableInEmbedded into @available(*, unavailable) when in
   // embedded Swift mode, or into nothing when in regular mode.
-  if (!DK && Tok.getText() == "_unavailableInEmbedded") {
+  if (!DK && Tok.getText() == UNAVAILABLE_IN_EMBEDDED_ATTRNAME) {
     SourceLoc attrLoc = consumeToken();
     if (Context.LangOpts.hasFeature(Feature::Embedded)) {
       StringRef Message = "unavailable in embedded Swift", Renamed;
-      auto attr = new (Context) AvailableAttr(AtLoc, SourceRange(AtLoc, attrLoc),
-                  PlatformKind::none,
-                  Message, Renamed, /*RenameDecl=*/nullptr,
-                  llvm::VersionTuple(), SourceRange(),
-                  llvm::VersionTuple(), SourceRange(),
-                  llvm::VersionTuple(), SourceRange(),
-                  PlatformAgnosticAvailabilityKind::Unavailable,
-                  /*Implicit=*/false, /*IsSPI=*/false);
+      auto attr = new (Context) AvailableAttr(
+          AtLoc, SourceRange(AtLoc, attrLoc), PlatformKind::none, Message,
+          Renamed, /*RenameDecl=*/nullptr, llvm::VersionTuple(), SourceRange(),
+          llvm::VersionTuple(), SourceRange(), llvm::VersionTuple(),
+          SourceRange(), PlatformAgnosticAvailabilityKind::Unavailable,
+          /*Implicit=*/false, /*IsSPI=*/false, /*IsForEmbedded=*/true);
       Attributes.add(attr);
     }
     return makeParserSuccess();

lib/Sema/TypeCheckAttr.cpp

@@ -2105,7 +2105,7 @@ void AttributeChecker::visitAvailableAttr(AvailableAttr *attr) {
     return;
 
   // FIXME: This seems like it could be diagnosed during parsing instead.
-  while (attr->IsSPI) {
+  while (attr->isSPI()) {
     if (attr->hasPlatform() && attr->Introduced.has_value())
       break;
     diagnoseAndRemoveAttr(attr, diag::spi_available_malformed);
@@ -4673,7 +4673,7 @@ void AttributeChecker::checkAvailableAttrs(ArrayRef<AvailableAttr *> Attrs) {
   if (!D->getDeclContext()->getInnermostDeclarationDeclContext()) {
     // If all available are spi available, we should use @_spi instead.
     if (std::all_of(Attrs.begin(), Attrs.end(), [](AvailableAttr *AV) {
-      return AV->IsSPI;
+      return AV->isSPI();
     })) {
       diagnose(D->getLoc(), diag::spi_preferred_over_spi_available);
     }

lib/Sema/TypeCheckConcurrency.cpp

@@ -6604,7 +6604,7 @@ static void addUnavailableAttrs(ExtensionDecl *ext, NominalTypeDecl *nominal) {
           available->Obsoleted.value_or(noVersion), SourceRange(),
           PlatformAgnosticAvailabilityKind::Unavailable,
           /*implicit=*/true,
-          available->IsSPI);
+          available->isSPI());
       ext->getAttrs().add(attr);
       anyPlatformSpecificAttrs = true;
     }

lib/Serialization/Deserialization.cpp

@@ -5602,6 +5602,7 @@ DeclDeserializer::readAvailable_DECL_ATTR(SmallVectorImpl<uint64_t> &scratch,
   bool isNoAsync;
   bool isPackageDescriptionVersionSpecific;
   bool isSPI;
+  bool isForEmbedded;
   DEF_VER_TUPLE_PIECES(Introduced);
   DEF_VER_TUPLE_PIECES(Deprecated);
   DEF_VER_TUPLE_PIECES(Obsoleted);
@@ -5611,7 +5612,7 @@ DeclDeserializer::readAvailable_DECL_ATTR(SmallVectorImpl<uint64_t> &scratch,
   // Decode the record, pulling the version tuple information.
   serialization::decls_block::AvailableDeclAttrLayout::readRecord(
       scratch, isImplicit, isUnavailable, isDeprecated, isNoAsync,
-      isPackageDescriptionVersionSpecific, isSPI,
+      isPackageDescriptionVersionSpecific, isSPI, isForEmbedded,
       LIST_VER_TUPLE_PIECES(Introduced), LIST_VER_TUPLE_PIECES(Deprecated),
       LIST_VER_TUPLE_PIECES(Obsoleted), rawPlatform, renameDeclID, messageSize,
       renameSize);
@@ -5655,7 +5656,7 @@ DeclDeserializer::readAvailable_DECL_ATTR(SmallVectorImpl<uint64_t> &scratch,
   auto attr = new (ctx) AvailableAttr(
       SourceLoc(), SourceRange(), platform, message, rename, renameDecl,
       Introduced, SourceRange(), Deprecated, SourceRange(), Obsoleted,
-      SourceRange(), platformAgnostic, isImplicit, isSPI);
+      SourceRange(), platformAgnostic, isImplicit, isSPI, isForEmbedded);
   return attr;
 }
 

lib/Serialization/ModuleFormat.h

@@ -58,7 +58,7 @@ const uint16_t SWIFTMODULE_VERSION_MAJOR = 0;
 /// describe what change you made. The content of this comment isn't important;
 /// it just ensures a conflict if two people change the module format.
 /// Don't worry about adhering to the 80-column limit for this line.
-const uint16_t SWIFTMODULE_VERSION_MINOR = 899; // Builtin.FixedArray serialize
+const uint16_t SWIFTMODULE_VERSION_MINOR = 900; // @_unavailableInEmbedded
 
 /// A standard hash seed used for all string hashes in a serialized module.
 ///
@@ -2351,6 +2351,7 @@ namespace decls_block {
     BCFixed<1>, // is unavailable from async?
     BCFixed<1>, // is this PackageDescription version-specific kind?
     BCFixed<1>, // is SPI?
+    BCFixed<1>, // is for Embedded
     BC_AVAIL_TUPLE, // Introduced
     BC_AVAIL_TUPLE, // Deprecated
     BC_AVAIL_TUPLE, // Obsoleted

lib/Serialization/Serialization.cpp

@@ -3031,7 +3031,8 @@ class Serializer::DeclSerializer : public DeclVisitor<DeclSerializer> {
           theAttr->isUnconditionallyDeprecated(),
           theAttr->isNoAsync(),
           theAttr->isPackageDescriptionVersionSpecific(),
-          theAttr->IsSPI,
+          theAttr->isSPI(),
+          theAttr->isForEmbedded(),
           LIST_VER_TUPLE_PIECES(Introduced),
           LIST_VER_TUPLE_PIECES(Deprecated),
           LIST_VER_TUPLE_PIECES(Obsoleted),

test/attr/attr_unavailable_in_embedded.swift

@@ -0,0 +1,13 @@
+// RUN: %target-swift-frontend -typecheck %s -parse-stdlib -print-ast | %FileCheck %s --check-prefix=CHECK-NON-EMBEDDED
+// RUN: %target-swift-frontend -typecheck %s -parse-stdlib -enable-experimental-feature Embedded -print-ast | %FileCheck %s --check-prefix=CHECK-EMBEDDED
+
+// CHECK-NON-EMBEDDED-NOT: @available
+// CHECK-NON-EMBEDDED-NOT: @_unavailableInEmbedded
+// CHECK-NON-EMBEDDED:     public func unavailable()
+
+// CHECK-EMBEDDED-NOT:  @available
+// CHECK-EMBEDDED:      @_unavailableInEmbedded
+// CHECK-EMBEDDED-NEXT: public func unavailable()
+
+@_unavailableInEmbedded
+public func unavailable() {}

test/embedded/attr-unavailable-in-embedded.swift

@@ -0,0 +1,21 @@
+// RUN: %empty-directory(%t)
+// RUN: %{python} %utils/split_file.py -o %t %s
+
+// RUN: %target-swift-frontend -emit-module -o %t/MyModule.swiftmodule %t/MyModule.swift -enable-experimental-feature Embedded -parse-as-library
+// RUN: %target-swift-frontend -typecheck -verify -I %t %t/Main.swift -enable-experimental-feature Embedded
+
+// REQUIRES: swift_in_compiler
+
+// BEGIN MyModule.swift
+
+@_unavailableInEmbedded
+public func unavailable() { }
+
+// BEGIN Main.swift
+
+import MyModule
+
+func available() {
+  unavailable() // expected-error {{'unavailable()' is unavailable: unavailable in embedded Swift}}
+}
+