How to stringize string with trailing backslash - c++

Question

When I build my C++ project the compiler generates this equivalent macro:
#define SOLUTION_DIR "c:\dev\my_project\"
In a normally #defined macro the trailing escaped double quotes would trigger compiler errors due to the unterminated string but compiler can do whatever it wants and makes this available to the code literally even if the string is invalid.
The usual way to expand macro values to C strings:
#define STRINGIZE( x ) #x
#define EXPAND( x ) STRINGIZE( x )
doesn't work in this case due to the unterminated string passed as argument.
std::string s = EXPAND( SOLUTION_DIR );
...
error: newline in constant
Is there a way to extract the string value of this macro and use it in my code equivalent to:
std::string str = R"(c:\dev\my_project\)";
where R is raw character prefix described here https://en.cppreference.com/w/cpp/language/string_literal
Notes:
I tried re-writing these macros using the R prefix to avoid escaping
the final quote mark but couldn't get to a functional version.
I can tell the compiler to define SOLUTION_DIR string without the
surrounding quotes, but I can't avoid the trailing backslash. In
this case however I get other warnings and errors due to the unknown
escape sequences (\d) and the fact that the trailing
backslash is taken to indicate that the macro is continuing on
the next line.
Update:
Here's the context for those who think something is broken and needs to be fixed.
I use Visual Studio 2019 (VS). In the project properties "C++/Preprocessor/Preprocessor Definitions" one can define various macros in the format:
NAME1=VALUE1;NAME2=VALUE2;...
which are then made available at compile time as
#define NAME1 VALUE1
#define NAME2 VALUE2
VS generates a number of predefined macros (not C++ but build environment macros) for various directories and other values (debug/release, 32 or 64 bit etc). They take the form $(Name) and are set to some string value such as:
$(Configuration) Debug
$(SolutionDir) C:\dev\some_project\
They are used to create location independent project settings such as the temp or binary output directories, or set the correct environment for whatever version of the project is being built (for instance Debug/x64).
In my case I need to get a hold of the current solution path directly in my code, and using the $(SolutionDir) VS macro seemed the easiest way to do it.
So here's how I defined my SOLUTION_PATH macro in "Properties/Preprocessor/Preprocessor Definitions":
SOLUTION_DIR="$(SolutionDir)
which translates into the compile time macro described initially:
#define SOLUTION_DIR "c:\dev\my_project\"
However, by default many macros that expand to paths, including $(SolutionDir), contain a trailing backslash which can't be removed hence the "broken" macro above.
Generally an executable binary doesn't need to and should not know anything about its build directories, so the path related macros are not necessarily designed to be used to define C++ macros, and the trailing backslash is not an issue. But my project needs that information because it itself triggers other build actions that depend on the current environment.
So this is not a malfunction of any of the components, everything works as designed, it just happens that for my specific project it would be very useful to be able to do things this way, even if it's non-standard.

Answer 1

I was able to make this work by adding a trailing ".":
SOLUTION_DIR="$(SolutionDir)."
which results in the equivalent:
#define SOLUTION_DIR "C:\dev\my_project\."
which points to the same directory and now compiles with no errors.