[Macros] Deserialization and printing for @attached.

include/swift/AST/MacroDeclaration.h

@@ -37,6 +37,10 @@ enum class MacroRole: uint32_t {
 /// The contexts in which a particular macro declaration can be used.
 using MacroRoles = OptionSet<MacroRole>;
 
+/// Retrieve the string form of the given macro role, as written on the
+/// corresponding attribute.
+StringRef getMacroRoleString(MacroRole role);
+
 /// Whether a macro with the given set of macro contexts is freestanding, i.e.,
 /// written in the source code with the `#` syntax.
 bool isFreestandingMacro(MacroRoles contexts);
@@ -53,6 +57,12 @@ enum class MacroIntroducedDeclNameKind {
   Arbitrary,
 };
 
+/// Whether a macro-introduced name of this kind requires an argument.
+bool macroIntroducedNameRequiresArgument(MacroIntroducedDeclNameKind kind);
+
+StringRef getMacroIntroducedDeclNameString(
+    MacroIntroducedDeclNameKind kind);
+
 class MacroIntroducedDeclName {
 public:
   using Kind = MacroIntroducedDeclNameKind;

lib/AST/Attr.cpp

@@ -1309,6 +1309,30 @@ bool DeclAttribute::printImpl(ASTPrinter &Printer, const PrintOptions &Options,
     break;
   }
 
+  case DAK_Attached: {
+    Printer.printAttrName("@attached");
+    Printer << "(";
+    auto Attr = cast<AttachedAttr>(this);
+    Printer << getMacroRoleString(Attr->getMacroRole());
+    if (!Attr->getNames().empty()) {
+      Printer << ", names: ";
+      interleave(
+          Attr->getNames(),
+          [&](MacroIntroducedDeclName name) {
+            Printer << getMacroIntroducedDeclNameString(name.getKind());
+            if (macroIntroducedNameRequiresArgument(name.getKind())) {
+              Printer << "(" << name.getIdentifier() << ")";
+            }
+          },
+          [&] {
+            Printer << ", ";
+          }
+      );
+    }
+    Printer << ")";
+    break;
+  }
+
   case DAK_Count:
     llvm_unreachable("exceed declaration attribute kinds");
 

lib/AST/Decl.cpp

@@ -9672,6 +9672,54 @@ BuiltinTupleDecl::BuiltinTupleDecl(Identifier Name, DeclContext *Parent)
     : NominalTypeDecl(DeclKind::BuiltinTuple, Parent, Name, SourceLoc(),
                       ArrayRef<InheritedEntry>(), nullptr) {}
 
+StringRef swift::getMacroRoleString(MacroRole role) {
+  switch (role) {
+  case MacroRole::Expression:
+    return "expression";
+
+  case MacroRole::FreestandingDeclaration:
+    return "freestanding";
+
+  case MacroRole::Accessor:
+    return "accessor";
+  }
+}
+
+bool swift::macroIntroducedNameRequiresArgument(
+  MacroIntroducedDeclNameKind kind
+) {
+  switch (kind) {
+  case MacroIntroducedDeclNameKind::Named:
+  case MacroIntroducedDeclNameKind::Prefixed:
+  case MacroIntroducedDeclNameKind::Suffixed:
+    return true;
+
+  case MacroIntroducedDeclNameKind::Overloaded:
+  case MacroIntroducedDeclNameKind::Arbitrary:
+    return false;
+  }
+}
+
+StringRef swift::getMacroIntroducedDeclNameString(
+    MacroIntroducedDeclNameKind kind) {
+  switch (kind) {
+  case MacroIntroducedDeclNameKind::Named:
+    return "named";
+
+  case MacroIntroducedDeclNameKind::Overloaded:
+    return "overloaded";
+
+  case MacroIntroducedDeclNameKind::Prefixed:
+    return "prefixed";
+
+  case MacroIntroducedDeclNameKind::Suffixed:
+    return "suffixed";
+
+  case MacroIntroducedDeclNameKind::Arbitrary:
+    return "arbitrary";
+  }
+}
+
 static MacroRoles freestandingMacroRoles =
   (MacroRoles() |
    MacroRole::Expression |

lib/Parse/ParseDecl.cpp

@@ -2236,21 +2236,6 @@ static Optional<MacroRole> getMacroRole(
   return role;
 }
 
-/// Determine whether a macro-introduced name requires an argument (which is
-/// always a string literal).
-static bool introducedNameRequiresArgument(MacroIntroducedDeclNameKind kind) {
-  switch (kind) {
-  case MacroIntroducedDeclNameKind::Named:
-  case MacroIntroducedDeclNameKind::Prefixed:
-  case MacroIntroducedDeclNameKind::Suffixed:
-    return true;
-
-  case MacroIntroducedDeclNameKind::Overloaded:
-  case MacroIntroducedDeclNameKind::Arbitrary:
-    return false;
-  }
-}
-
 static Optional<MacroIntroducedDeclNameKind>
 getMacroIntroducedDeclNameKind(Identifier name) {
   return llvm::StringSwitch<Optional<MacroIntroducedDeclNameKind>>(name.str())
@@ -2307,7 +2292,7 @@ static SmallVector<MacroIntroducedDeclName, 2> getMacroIntroducedNames(
         continue;
       }
 
-      if (introducedNameRequiresArgument(*introducedKind)) {
+      if (macroIntroducedNameRequiresArgument(*introducedKind)) {
         diags.diagnose(
             arg.getExpr()->getLoc(),
             diag::macro_attribute_introduced_name_requires_argument,
@@ -2352,7 +2337,7 @@ static SmallVector<MacroIntroducedDeclName, 2> getMacroIntroducedNames(
       continue;
     }
 
-    if (!introducedNameRequiresArgument(*introducedKind)) {
+    if (!macroIntroducedNameRequiresArgument(*introducedKind)) {
       diags.diagnose(
           call->getArgs()->getLoc(),
           diag::macro_attribute_introduced_name_requires_no_argument,

lib/Serialization/Deserialization.cpp

@@ -5447,6 +5447,30 @@ llvm::Error DeclDeserializer::deserializeDeclCommon() {
         break;
       }
 
+      case decls_block::Attached_DECL_ATTR: {
+        bool isImplicit;
+        uint8_t rawMacroRole;
+        uint64_t numNames;
+        ArrayRef<uint64_t> introducedDeclNames;
+        serialization::decls_block::AttachedDeclAttrLayout::
+            readRecord(scratch, isImplicit, rawMacroRole, numNames,
+                       introducedDeclNames);
+        auto role = *getActualMacroRole(rawMacroRole);
+        if (introducedDeclNames.size() != numNames * 2)
+          return MF.diagnoseFatal();
+        SmallVector<MacroIntroducedDeclName, 1> names;
+        for (unsigned i = 0; i < introducedDeclNames.size(); i += 2) {
+          auto kind = getActualMacroIntroducedDeclNameKind(
+              (uint8_t)introducedDeclNames[i]);
+          auto identifier =
+              MF.getIdentifier(IdentifierID(introducedDeclNames[i + 1]));
+          names.push_back(MacroIntroducedDeclName(*kind, identifier));
+        }
+        Attr = AttachedAttr::create(
+            ctx, SourceLoc(), SourceRange(), role, names, isImplicit);
+        break;
+      }
+
 #define SIMPLE_DECL_ATTR(NAME, CLASS, ...) \
       case decls_block::CLASS##_DECL_ATTR: { \
         bool isImplicit; \

test/ModuleInterface/macros.swift

@@ -16,5 +16,10 @@
 // CHECK-NEXT: #endif
 @expression public macro publicLine<T: ExpressibleByIntegerLiteral>: T = #externalMacro(module: "SomeModule", type: "Line")
 
+// CHECK: #if compiler(>=5.3) && $Macros
+// CHECK: @attached(accessor) public macro myWrapper: Swift.Void = #externalMacro(module: "SomeModule", type: "Wrapper")
+// CHECK-NEXT: #endif
+@attached(accessor) public macro myWrapper: Void = #externalMacro(module: "SomeModule", type: "Wrapper")
+
 // CHECK-NOT: internalStringify
 @expression macro internalStringify<T>(_ value: T) -> (T, String) = #externalMacro(module: "SomeModule", type: "StringifyMacro")

test/Serialization/Inputs/def_macros.swift

@@ -1,3 +1,5 @@
 @expression public macro publicStringify<T>(_ value: T) -> (T, String) = SomeModule.StringifyMacro
 
 @expression macro internalStringify<T>(_ value: T) -> (T, String) = SomeModule.StringifyMacro
+
+@attached(accessor) public macro myWrapper: Void = SomeModule.MyWrapperMacro

test/Serialization/macros.swift

@@ -15,3 +15,8 @@ func test(a: Int, b: Int) {
   _ = #internalStringify(a + b)
   // expected-error@-1{{no macro named 'internalStringify'}}
 }
+
+struct TestStruct {
+  @myWrapper var x: Int
+  // expected-error@-1{{external macro implementation type 'SomeModule.MyWrapperMacro' could not be found for macro 'myWrapper'}}
+}