// Copyright David Abrahams 2002.

// Distributed under the Boost Software License, Version 1.0. (See

// accompanying file LICENSE_1_0.txt or copy at

// http://www.boost.org/LICENSE_1_0.txt)

#ifndef WORKAROUND_DWA2002126_HPP

# define WORKAROUND_DWA2002126_HPP

// Compiler/library version workaround macro

//

// Usage:

//

//     #if BOOST_WORKAROUND(BOOST_MSVC, < 1300)

//        // workaround for eVC4 and VC6

//        ... // workaround code here

//     #endif

//

// When BOOST_STRICT_CONFIG is defined, expands to 0. Otherwise, the

// first argument must be undefined or expand to a numeric

// value. The above expands to:

//

//     (BOOST_MSVC) != 0 && (BOOST_MSVC) < 1300

//

// When used for workarounds that apply to the latest known version 

// and all earlier versions of a compiler, the following convention 

// should be observed:

//

//     #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1301))

//

// The version number in this case corresponds to the last version in

// which the workaround was known to have been required. When

// BOOST_DETECT_OUTDATED_WORKAROUNDS is not the defined, the macro

// BOOST_TESTED_AT(x) expands to "!= 0", which effectively activates

// the workaround for any version of the compiler. When

// BOOST_DETECT_OUTDATED_WORKAROUNDS is defined, a compiler warning or

// error will be issued if the compiler version exceeds the argument

// to BOOST_TESTED_AT().  This can be used to locate workarounds which

// may be obsoleted by newer versions.

# ifndef BOOST_STRICT_CONFIG

#  define BOOST_WORKAROUND(symbol, test)                \

        ((symbol != 0) && (1 % (( (symbol test) ) + 1)))

//                              ^ ^           ^ ^

// The extra level of parenthesis nesting above, along with the

// BOOST_OPEN_PAREN indirection below, is required to satisfy the

// broken preprocessor in MWCW 8.3 and earlier.

//

// The basic mechanism works as follows:

//      (symbol test) + 1        =>   if (symbol test) then 2 else 1

//      1 % ((symbol test) + 1)  =>   if (symbol test) then 1 else 0

//

// The complication with % is for cooperation with BOOST_TESTED_AT().

// When "test" is BOOST_TESTED_AT(x) and

// BOOST_DETECT_OUTDATED_WORKAROUNDS is #defined,

//

//      symbol test              =>   if (symbol <= x) then 1 else -1

//      (symbol test) + 1        =>   if (symbol <= x) then 2 else 0

//      1 % ((symbol test) + 1)  =>   if (symbol <= x) then 1 else divide-by-zero

//

#  ifdef BOOST_DETECT_OUTDATED_WORKAROUNDS

#   define BOOST_OPEN_PAREN (

#   define BOOST_TESTED_AT(value)  > value) ?(-1): BOOST_OPEN_PAREN 1

#  else

#   define BOOST_TESTED_AT(value) != ((value)-(value))

#  endif

# else

#  define BOOST_WORKAROUND(symbol, test) 0

# endif 

#endif // WORKAROUND_DWA2002126_HPP