Re: [Boost-testing] Error compiling Boost.System

From: Beman Dawes (bdawes_at_[hidden])
Date: 2007-09-27 13:08:17

Christopher Cambly wrote:
> I'm getting an error compiling system/src/error_code.cpp with IBM XL C/C++
> that started a couple days ago.  The error issued from the IBM XL compiler
> is:
> 
> "../../../libs/system/src/error_code.cpp", line 211.5: 1540-0240 (S) A
> duplicate case value is not allowed.
> 
> The problem is that AIX /usr/include/errno.h #define's ENOTEMPTY  to
> EEXIST causing the duplicate constant-expressions in the case statement.
> 
> The Posix standard seems to require that the values be unique.  AIX by
> default treats ENOTEMPTY and EEXIST as the same value.   To have AIX define
> the macros ENOTEMPTY and EEXIST with different values one needs to define
> the macro _LINUX_SOURCE_COMPAT.   Unfortunately in this case,  leaving the
> _LINUX_SOURCE_COMPAT macro defined introduces different declarations for
> some other Posix  functions so it also needs to be undef'd [strerror_r()
> gets a non-Posix declaration which causes some problems later on in
> error_code.cpp].
> 
> The patch below works, however may not be ideal.  I am wondering if there a
> better place in the boost source to make such a change?

This is the third case so far of two POSIX macros being defined as the 
same value. The others being EOPNOTSUPP / ENOTSUP and EAGAIN / 
EWOULDBLOCK. The recipe we are using to cope is:

   # if ENOTEMPTY != EEXIST
     case ENOTEMPTY: return make_error_condition( directory_not_empty );
   # endif // ENOTEMPTY != EEXIST

The advantage being that it works for any other system that happens to 
have done the same thing.

I've committed this change to SVN.

>  As an aside, one
> of our developers mentioned that  Boost.Filesystem has a similar problem
> with the macros ENOTEMPTY and EEXIST not being unique, however I not
> verified this yet.

Was this in operations.cpp? The code I see there will still work if the 
two macros define the same value, unless I'm missing something.

Thanks for the help,

--Beman

> 
> --- boost/system/error_code.hpp~        2007-09-21 07:45:23.000000000 -0400
> +++ boost/system/error_code.hpp 2007-09-26 22:23:04.146591954 -0400
> @@ -17,7 +17,14 @@
>  #include <boost/operators.hpp>
>  #include <boost/noncopyable.hpp>
>  #include <boost/utility/enable_if.hpp>
> +#if defined(_AIX)
> +#define _LINUX_SOURCE_COMPAT
> +#endif
>  #include <ostream>
> +#if defined(_AIX)
> +#undef _LINUX_SOURCE_COMPAT
> +#endif
> +
>  #include <string>
>  #include <stdexcept>
>  #include <functional>
> 
> Chris Cambly
> XL C++ Compiler Development