[interop][SwiftToCxx] do not print documentation comment for emitted methods if they're not actually emitted

Author: hyp

lib/PrintAsClang/DeclAndTypePrinter.cpp

@@ -902,8 +902,6 @@ class DeclAndTypePrinter::Implementation
                                      bool isClassMethod,
                                      bool isNSUIntegerSubscript = false,
                                      const SubscriptDecl *SD = nullptr) {
-    printDocumentationComment(AFD);
-
     Optional<ForeignAsyncConvention> asyncConvention =
         AFD->getForeignAsyncConvention();
     Optional<ForeignErrorConvention> errorConvention =
@@ -930,6 +928,7 @@ class DeclAndTypePrinter::Implementation
         return;
       owningPrinter.prologueOS << cFuncPrologueOS.str();
 
+      printDocumentationComment(AFD);
       DeclAndTypeClangFunctionPrinter declPrinter(
           os, owningPrinter.prologueOS, owningPrinter.typeMapping,
           owningPrinter.interopContext, owningPrinter);
@@ -978,6 +977,7 @@ class DeclAndTypePrinter::Implementation
       // FIXME: availability
       return;
     }
+    printDocumentationComment(AFD);
 
     if (isClassMethod)
       os << "+ (";

test/Interop/SwiftToCxx/stdlib/stdlib-dep-inline-in-cxx.swift

@@ -7,7 +7,7 @@
 
 // RUN: cat %t/stdlib.h %t/stdlib2.h > %t/two_includes.h
 
-// RUN: %check-generic-interop-cxx-header-in-clang(%t/two_includes.h -Wno-unused-private-field -Wno-unused-function -Wno-shadow -Wno-documentation)
+// RUN: %check-generic-interop-cxx-header-in-clang(%t/two_includes.h -Wno-unused-private-field -Wno-unused-function -Wno-shadow)
 
 @_expose(Cxx)
 public func test() -> String {