Question: .L Test.cpp+ fails , why?

The following test program (Test.cpp) fails with.L + Test.cpp+, but not with plain .L, nor with gcc. It also does not tell me anything about why where it fails!

#include <string>
int Test(std::string x) {
cout << x << "\n";
 return 1;
};

Error in <ACLiC>: Executing 'C:\root_v6.28.06\bin\rootcling -v0 "--lib-list-prefix=C:\Users\snyde\BFROOT\ROOT\Test_cpp_ACLiC_map" -f "C:\Users\snyde\BFROOT\ROOT\Test_cpp_ACLiC_dict.cxx"  -rml Test_cpp -rmf "C:\Users\snyde\BFROOT\ROOT\Test_cpp.rootmap" -DR__ACLIC_ROOTMAP -I%ROOTSYS%\include -D__ACLIC__  "C:/Users/snyde/BFROOT/ROOT/Test.cpp" "C:\Users\snyde\BFROOT\ROOT\Test_cpp_ACLiC_linkdef.h"' failed!

Huh? Why?

I can't learn what's wrong using 'g++  -c Test.cpp' (outside ROOT)  as it compiles w/o complaint in that case.

Is there a way to get ROOT to tell us what it objects to?