[AST printer] Stop printing -> () types on all macro declarations.

Author: DougGregor

lib/AST/ASTPrinter.cpp

@@ -4780,16 +4780,14 @@ void PrintAST::visitMacroDecl(MacroDecl *decl) {
       }
   );
 
-  {
+  if (decl->resultType.getTypeRepr() ||
+      !decl->getResultInterfaceType()->isVoid()) {
     Printer.printStructurePre(PrintStructureKind::DeclResultTypeClause);
     SWIFT_DEFER {
       Printer.printStructurePost(PrintStructureKind::DeclResultTypeClause);
     };
 
-    if (decl->parameterList)
-      Printer << " -> ";
-    else
-      Printer << ": ";
+    Printer << " -> ";
 
     TypeLoc resultTypeLoc(
         decl->resultType.getTypeRepr(), decl->getResultInterfaceType());

test/ModuleInterface/macros.swift

@@ -30,14 +30,14 @@
 @freestanding(expression) public macro publicLine<T: ExpressibleByIntegerLiteral>() -> T = #externalMacro(module: "SomeModule", type: "Line")
 
 // CHECK: #if compiler(>=5.3) && $Macros
-// CHECK: @attached(accessor) public macro myWrapper() -> () = #externalMacro(module: "SomeModule", type: "Wrapper")
+// CHECK: @attached(accessor) public macro myWrapper() = #externalMacro(module: "SomeModule", type: "Wrapper")
 // CHECK-NEXT: #endif
 @attached(accessor) public macro myWrapper() = #externalMacro(module: "SomeModule", type: "Wrapper")
 
 // CHECK: #if compiler(>=5.3) && $Macros && $AttachedMacros
-// CHECK: @attached(member, names: named(`init`), prefixed(`$`)) public macro MemberwiseInit() -> () = #externalMacro(module: "SomeModule", type: "MemberwiseInitMacro")
+// CHECK: @attached(member, names: named(`init`), prefixed(`$`)) public macro MemberwiseInit() = #externalMacro(module: "SomeModule", type: "MemberwiseInitMacro")
 // CHECK-NEXT: #endif
-@attached(member, names: named(init), prefixed(`$`)) public macro MemberwiseInit() -> () = #externalMacro(module: "SomeModule", type: "MemberwiseInitMacro")
+@attached(member, names: named(init), prefixed(`$`)) public macro MemberwiseInit() = #externalMacro(module: "SomeModule", type: "MemberwiseInitMacro")
 
 // CHECK-NOT: internalStringify
 @freestanding(expression) macro internalStringify<T>(_ value: T) -> (T, String) = #externalMacro(module: "SomeModule", type: "StringifyMacro")