// 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