C++0x legacy code problem [closed]

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As all you know, C++0x 开发者_开发问答can't bring lots of important changes because of legacy code: all legacy code (including C code) can be compilable with a C++0x compiler.

So why don't add something like #pragma syntax(language_version), which will allow new syntax with breaking changes?

#include <legacy_code_header.h>

#pragma syntax(2098)

// something strange
func(x)
{
   return x + 1, x * 2;
}

int main()
{
   a, b = func(1.0);
   return a + b;
}

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Some C++0x compilers might allow this. After all, #pragmas are generally compiler specific and not dictated by the standard. Others support this with command line options.