[libcxx] r194891 - Fix-it suggestion for fixing min or max defines on Windows.

[Arthur O'Dwyer]

On Fri, Nov 15, 2013 at 3:41 PM, Yaron Keren <yaron.keren at gmail.com> wrote:
>
> -_LIBCPP_WARNING("macro min is incompatible with C++.  #undefing min")
> +_LIBCPP_WARNING("macro min is incompatible with C++.  Try #define NOMINMAX "
> +                "before any Windows header. #undefing min")

Incidentally, this warning has annoyed me in the past when compiling
MySQL 5.5 as C++. They have some code (in the name of portability, I'm
sure) equivalent to

    #ifndef max
     #define min(a,b) (a < b ? a : b)
     #define max(a,b) (a > b ? a : b)
    #endif

which I try to disable by putting

    #define max max

in another header. By #undef'ing max, libc++ interferes with this
tactic — or rather, it's hard to tell for any given translation unit
whether it interferes with it or not (depending on the order of
#includes), which is even more distracting. I wonder whether it would
be possible for the libc++ header to use

    #undef max
    #define max max

instead of just "#undef max", or if the Standard prohibits that somehow.

Not that I expect a change to happen, but I figured I should publicly
register my particular use-case.

–Arthur