Re: [Boost-users] \boost\cstdint.hpp(129) : error C2059: syntax error : '::'

Subject: Re: [Boost-users] \boost\cstdint.hpp(129) : error C2059: syntax error : '::'
From: Gavin Lambert (gavinl_at_[hidden])
Date: 2014-03-05 16:55:36

On 6/03/2014 03:13, Quoth Krzysztof Czainski:
> Ok, so you have a group of external headers that do evil things like
> #define uint64_t. Here's what I do in cases like this.
>
> //evil_prefix.h:
> // Note: this file intentionally has no include guards.
> #include "evil/a.h" // #defines uint64_t
> #if !defined(uint64_t)
> // these are the 3 offending lines copied from "evli/a.h":
> #if defined(OS_WIN) && !defined(uint64_t)
> #define uint64_t unsigned __int64
> #endif
> #endif // uint64_t
>
> //evli_suffix.h:
> // Note: this file intentionally has no include guards.
> #undef uint64_t
>
>
> Armed with the above two header files, in all your files _always_
> include all evil headers between the prefix and suffix includes:
>
> #include "evil_prefix.h"
> #include "evil/a.h"
> #include "evil/b.h"
> ...
> #include "evil_suffix.h"

The suffix header makes sense, but I'm not sure what the purpose of the 
prefix header file is.  It seems like overkill to include the offending 
header, repeat the offending #define, and then include the header *again*.

It also doesn't really help with the OP's case.  What you actually need 
to do, if you *really* can't modify the offending application file 
(which is most definitely the best option) is to make your library 
header defensive:

SomeLibThatNeedsBoost.h:

   #pragma push_macro("uint64_t")
   #undef uint64_t
   // entire normal contents of the header here, including boost #include
   #pragma pop_macro("uint64_t")

But again, it is *far* far better to remove the evil #define in the 
original file.  Especially since cstdint will give you uint64_t anyway.