/*
 * File:   warnings_1.cpp
 * Author: Paul
 *
 * Created on 06 December 2012, 09:56
 *
 * -Wall -Wno-unused-variable -Wno-maybe-uninitialized -Wno-uninitialized
 */

#ifdef __clang__
#  define CLANG_DIAG_STR(s) # s
// stringize s to "no-unused-variable"
#  define CLANG_DIAG_JOINSTR(x,y) CLANG_DIAG_STR(x ## y)
//  join -W with no-unused-variable to "-Wno-unused-variable"
#  define CLANG_DIAG_DO_PRAGMA(x) _Pragma (#x)
// _Pragma is unary operator  #pragma ("")
#  define CLANG_DIAG_PRAGMA(x) CLANG_DIAG_DO_PRAGMA(clang diagnostic x)
#    define CLANG_DIAG_OFF(x) CLANG_DIAG_PRAGMA(push) \
          CLANG_DIAG_PRAGMA(ignored CLANG_DIAG_JOINSTR(-W,x))
// For example: #pragma clang diagnostic ignored "-Wno-unused-variable"
#   define CLANG_DIAG_ON(x) CLANG_DIAG_PRAGMA(pop)
// For example: #pragma clang diagnostic warning "-Wno-unused-variable"
#else // Ensure these macros so nothing for other compilers.
#  define CLANG_DIAG_OFF(x)
#  define CLANG_DIAG_ON(x)
#  define CLANG_DIAG_PRAGMA(x)
#endif

/* Usage:
  CLANG_DIAG_OFF(unused-variable)
  CLANG_DIAG_OFF(unused-parameter)
  CLANG_DIAG_OFF(uninitialized)
 */
#include <cstdlib>
#include <iostream>
#include <boost/assert.hpp>

int main()
{
  #ifdef __clang__
  std::cout << "Clang "<< __clang_major__ << '.' << __clang_minor__<< '.' << __clang_patchlevel__ << std::endl;
  #endif


// Clang method of saving and restoring current warning state.
  #pragma clang diagnostic push
  #pragma clang diagnostic pop

// Example of using Clang push'n'pop around two ignored warnings.
  #pragma clang diagnostic push
  #pragma clang diagnostic ignored "-Wmultichar"
  #pragma clang diagnostic ignored "-Wconstant-conversion"
  #pragma clang diagnostic ignored  "-Wunused-variable"
  char b = 'df'; // Most unwisely ignoring ALL warnings.
  #pragma clang diagnostic pop

// Example of using macro for push and pop pragmas.
  CLANG_DIAG_PRAGMA(push);
  #pragma clang diagnostic ignored "-Wunused-variable"
  int unused;
  CLANG_DIAG_PRAGMA(pop);

  // example of using macro to push warning state,suppress a warning and restore state.
  CLANG_DIAG_OFF(unused-variable)
  int unused_two;  // No warning from unused variable.
  CLANG_DIAG_ON(unused-variable) //

  int unused_too; // Expect a warning.


  return 0;
}

/*  Output:
  Clang 3.1.0

 clang++.exe -dD -Wall -Wextra   -c -g -Wall -I/i/boost-trunk -MMD -MP -MF build/Debug/MinGW_Clang-Windows/warnings_1.o.d -o build/Debug/MinGW_Clang-Windows/warnings_1.o warnings_1.cpp
warnings_1.cpp:97:7: warning: unused variable 'unused_too' [-Wunused-variable]
  int unused_too; // Expect a warning.
      ^
1 warning generated.
 *
 *
 * but for MSVC
 *
 ClCompile:
  warning_1.cpp
warning_1.cpp(77): warning C4068: unknown pragma
warning_1.cpp(78): warning C4068: unknown pragma
warning_1.cpp(81): warning C4068: unknown pragma
warning_1.cpp(82): warning C4068: unknown pragma
warning_1.cpp(83): warning C4068: unknown pragma
warning_1.cpp(84): warning C4068: unknown pragma
warning_1.cpp(85): warning C4305: 'initializing' : truncation from 'int' to 'char'
warning_1.cpp(85): warning C4309: 'initializing' : truncation of constant value
warning_1.cpp(86): warning C4068: unknown pragma
warning_1.cpp(90): warning C4068: unknown pragma
warning_1.cpp(99): warning C4101: 'unused_too' : unreferenced local variable
warning_1.cpp(96): warning C4101: 'unused_two' : unreferenced local variable
warning_1.cpp(85): warning C4189: 'b' : local variable is initialized but not referenced
warning_1.cpp(91): warning C4101: 'unused' : unreferenced local variable
j:\cpp\svg\warning_1\warning_1.cpp(66): warning C4701: potentially uninitialized local variable 'x' used

*/