[ASTGen] Generate '@reasync' and '@rethrows'

Also, fallback 'shouldBeRejectedByParser' attribute names to
'CustomAttr'.

Author: rintaro

include/swift/AST/ASTBridging.h

@@ -847,6 +847,9 @@ struct BridgedDeclAttributes {
   BRIDGED_INLINE swift::DeclAttributes unbridged() const;
 };
 
+SWIFT_NAME("BridgedDeclAttribute.shouldBeRejectedByParser(_:)")
+bool BridgedDeclAttribute_shouldBeRejectedByParser(BridgedDeclAttrKind cKind);
+
 SWIFT_NAME("BridgedDeclAttribute.isDeclModifier(_:)")
 bool BridgedDeclAttribute_isDeclModifier(BridgedDeclAttrKind cKind);
 

lib/AST/Bridging/DeclAttributeBridging.cpp

@@ -101,6 +101,13 @@ BridgedDeclAttribute BridgedDeclAttribute_createSimple(
                                      cAtLoc.unbridged(), cAttrLoc.unbridged());
 }
 
+bool BridgedDeclAttribute_shouldBeRejectedByParser(BridgedDeclAttrKind cKind) {
+  auto optKind = unbridged(cKind);
+  if (!optKind)
+    return false;
+  return DeclAttribute::shouldBeRejectedByParser(*optKind);
+}
+
 bool BridgedDeclAttribute_isDeclModifier(BridgedDeclAttrKind cKind) {
   auto optKind = unbridged(cKind);
   if (!optKind)

lib/ASTGen/Sources/ASTGen/DeclAttrs.swift

@@ -193,6 +193,10 @@ extension ASTGenVisitor {
         fatalError("unimplemented")
       case .unavailableFromAsync:
         return handle(self.generateUnavailableFromAsyncAttr(attribute: node)?.asDeclAttribute)
+      case .reasync:
+        return handle(self.generateSimpleDeclAttr(attribute: node, kind: .atReasync))
+      case .rethrows:
+        return handle(self.generateSimpleDeclAttr(attribute: node, kind: .atRethrows))
       case .none where attrName == "_unavailableInEmbedded":
         return handle(self.generateUnavailableInEmbeddedAttr(attribute: node)?.asDeclAttribute)
       case .none where attrName == "_functionBuilder":
@@ -329,11 +333,10 @@ extension ASTGenVisitor {
         .clangImporterSynthesizedType,
         .forbidSerializingReference,
         .custom,
-        .setterAccess,
-        .rethrows,
-        .reasync:
-        // TODO: Diagnose or fallback to custom attributes?
-        return
+        .setterAccess:
+        assert(BridgedDeclAttribute.shouldBeRejectedByParser(attrKind))
+        // Fall back to CustomAttr.
+        break
 
       case .none:
         // Fall back to CustomAttr.

test/ASTGen/attrs.swift

@@ -7,6 +7,7 @@
 // RUN:   -enable-experimental-feature LifetimeDependence \
 // RUN:   -enable-experimental-feature RawLayout \
 // RUN:   -enable-experimental-feature SymbolLinkageMarkers \
+// RUN:   -enable-experimental-concurrency \
 // RUN:   -enable-experimental-move-only \
 // RUN:   -enable-experimental-feature ParserASTGen \
 // RUN:   | %sanitize-address > %t/astgen.ast
@@ -18,6 +19,7 @@
 // RUN:   -enable-experimental-feature LifetimeDependence \
 // RUN:   -enable-experimental-feature RawLayout \
 // RUN:   -enable-experimental-feature SymbolLinkageMarkers \
+// RUN:   -enable-experimental-concurrency \
 // RUN:   -enable-experimental-move-only \
 // RUN:   | %sanitize-address > %t/cpp-parser.ast
 
@@ -32,8 +34,10 @@
 // RUN:   -enable-experimental-feature LifetimeDependence \
 // RUN:   -enable-experimental-feature RawLayout \
 // RUN:   -enable-experimental-feature SymbolLinkageMarkers \
+// RUN:   -enable-experimental-concurrency \
 // RUN:   -enable-experimental-move-only
 
+// REQUIRES: concurrency
 // REQUIRES: executable_test
 // REQUIRES: swift_swift_parser
 // REQUIRES: swift_feature_ParserASTGen
@@ -250,3 +254,8 @@ struct LayoutOuter {
   }
 }
 @_rawLayout(like: LayoutOuter.Nested<Int>) struct TypeExprTest: ~Copyable {}
+
+@reasync protocol ReasyncProtocol {}
+@rethrows protocol RethrowingProtocol {
+  func source() throws
+}