[cfe-dev] MS 128-bit literals don't always have the correct type

[Kim Gräsman]

(+cfe-dev)


---------- Forwarded message ----------
From: Kim Gräsman <kim.grasman at gmail.com>
Date: Mon, Sep 24, 2012 at 7:18 AM
Subject: Re: [cfe-dev] MS 128-bit literals don't always have the correct type
To: Richard Smith <richard at metafoo.co.uk>


Hi Richard,

On Mon, Sep 24, 2012 at 6:46 AM, Richard Smith <richard at metafoo.co.uk> wrote:
> Incidentally, we currently treat (for instance) 1000000000000000000i32 as a
> 64-bit integer. How does MSVC behave here? (Does i32 mean "this shall be an
> int32_t", or does it mean "this shall be *at least* an int32_t"?)

This:

#include <iostream>
#include <typeinfo>

int main(int argc, char* argv[])
{
  auto i = 1000000000000000000i32;
  std::cout << typeid(i).name() << ": " << i << std::endl;
  return 0;
}

prints

  int: -1486618624

So it looks like MSVC honors the literal suffix, no matter if the
value fits or not. Removing the i32 suffix makes it an __int64 of the
given value.

This is on VC++10, SP1.

- Kim