Can a compilation error be forced if a string argument is not a string literal?

Question

Let\'s say I have these two overloads:

void Log(const wchar_t* message)
{
    // Do something
}

void Log(const std::wstring& message)
{
    // Do someth         


        

Answer 1

Here's a quick example I just whipped up using the printf hack I suggested in the comments above:

#include <cstdio>

#define LOG_MACRO(x) do { if (0) printf(x); Log(x); } while (0)

void Log(const char *message)
{
    // do something
}

void function(void)
{
    const char *s = "foo";
    LOG_MACRO(s);
    LOG_MACRO("bar");
}

Output from compiling this one with Clang appears to be exactly what you're looking for:

$ clang++ -c -o example.o example.cpp
example.cpp:13:15: warning: format string is not a string literal
      (potentially insecure) [-Wformat-security]
    LOG_MACRO(s);
              ^
example.cpp:3:41: note: expanded from macro 'LOG_MACRO'
#define LOG_MACRO(x) do { if (0) printf(x); Log(x); } while (0)
                                        ^
1 warning generated.

I did have to switch to printf rather than wprintf, since the latter appears not to generate the warning - I guess that's probably a Clang bug, though.

GCC's output is similar:

$ g++ -c -o example.o example.cpp
example.cpp: In function ‘void function()’:
example.cpp:13: warning: format not a string literal and no format arguments
example.cpp:13: warning: format not a string literal and no format arguments

Edit: You can see the Clang bug here. I just added a comment about -Wformat-security.