[Bug c++/69683] New: multiline raw string R"()" for C++11 warning in false #ifdef when -std=c++98

[jcrada at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69683

            Bug ID: 69683
           Summary: multiline raw string R"()" for C++11 warning in false
                    #ifdef when -std=c++98
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jcrada at gmail dot com
  Target Milestone: ---

Created attachment 37590
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37590&action=edit
A test file

WHEN using a raw string `R"()"` within an `#ifdef X`
AND the given definition `X` is not defined
AND compiling with `-std=c++98` 
THEN the compiler emits `warning: missing terminating " character` for the
string
BUT it is expected from the compiler to ignore everything within the `#ifdef`
because `X` was not defined.

REPLICATE: 
gcc-6 -lstdc++ test.cpp  -std=c++98
test.cpp:6:22: warning: missing terminating " character
     std::string x = R"(My
                      ^

test.cpp:8:20: warning: missing terminating " character
             String)";
                    ^

`test.cpp` is shown below and it is attached too.

SYSTEM:
MacOSX Capitan 10.11.3 (15D21)
gcc-6 (Homebrew gcc6 6-20160110) 6.0.0 20160110 (experimental)

test.cpp:
`#include <iostream>

int main(int argc, char** argv){

#ifdef CPP11
    std::string x = R"(My 
            C++11
            String)";
#else
    std::string x = "My C++98 String";
#endif
    std::cout << x << std::endl;
    return 0;
}`