[Boost-users] [type_traits][regex] VC++ __fastcall /clr

From: Edward Diener (eddielee_at_[hidden])
Date: 2006-03-29 10:50:14

When compiling managed code in VC++ .NET, which is any of the /clr 
compiler options, the programmer can mix both CLR classes and regular 
C++ classes. In the regular C++ classes, Boost should work fine. The 
VC++ macro which tells one that managed code of any kind is being 
compiled is _MANAGED, which is defined if managed code is being compiled 
else it is not defined. So when any of the /clr compiler options are 
being used _MANAGED is defined, else it is not defined.

The VC++ compiler issues compiler warning C4561 whenever managed code is 
being compiled and __fastcall shows up as a calling convention in any 
way. Obviously the programmer can turn off this warning via a VC++ 
#pragma, but I am wondering if Boost could not change some of its 
headers to avoid this warning. In Boost bind and mem_fn, the programmer 
has to specifically ask for __fastcall support via special Boost macros 
to have any functions declared with the __fastcall calling convention, 
so nothing should be done there since it is clearly a programming error 
if he does so while compiling managed code.

However there are two other places in Boost which I have discovered 
where functions with the __fastcall calling convention are declared 
without the programmer doing anything.

The first, and most cumbersome reagrding warning messages, is in 
type_traits in the helper header files 
type_traits\detail\is_mem_fun_pointer_tester.hpp and 
type_traits\detail\is_function_pointer_tester.hpp. Since many other 
libraries, lambda in my case recently, uses type_traits, might not these 
headers be changed so that when VC++ is the compiler and _MANAGED is 
defined, the __fastcall versions of these helper functions are not 
declared ?

The second, which I have not encountered but which I saw while searching 
through Boost header code, is in regex\config.h and I do not know, given 
some other macros there, whether BOOST_REGEX_CALL can ever be __fastcall 
when compiling with /clr, but if it can perhaps a change can be made 
there also.

I know that it is not the purpose of Boost to try to accomodate C++ .NET 
programmers creating /clr compilations using Boost, especially when just 
warnings and not errors are issued. But in this case, using the 
predefined macro _MANAGED in VC++ and BOOST_MSVC, it would seem this 
acoomodation could be made. So I would like the Boost developers of 
type_traits, especially since it is used by so many other Boost 
libraries, and regex to consider it.