1 // Copyright David Abrahams 2002.
2 // Distributed under the Boost Software License, Version 1.0. (See
3 // accompanying file LICENSE_1_0.txt or copy at
4 // http://www.boost.org/LICENSE_1_0.txt)
5 #ifndef WORKAROUND_DWA2002126_HPP
6 # define WORKAROUND_DWA2002126_HPP
8 // Compiler/library version workaround macro
12 // #if BOOST_WORKAROUND(BOOST_MSVC, <= 1200)
13 // ... // workaround code here
16 // When BOOST_STRICT_CONFIG is defined, expands to 0. Otherwise, the
17 // first argument must be undefined or expand to a numeric
18 // value. The above expands to:
20 // (BOOST_MSVC) != 0 && (BOOST_MSVC) <= 1200
22 // When used for workarounds that apply to the latest known version
23 // and all earlier versions of a compiler, the following convention
24 // should be observed:
26 // #if BOOST_WORKAROUND(BOOST_MSVC, BOOST_TESTED_AT(1301))
28 // The version number in this case corresponds to the last version in
29 // which the workaround was known to have been required. When
30 // BOOST_DETECT_OUTDATED_WORKAROUNDS is not the defined, the macro
31 // BOOST_TESTED_AT(x) expands to "!= 0", which effectively activates
32 // the workaround for any version of the compiler. When
33 // BOOST_DETECT_OUTDATED_WORKAROUNDS is defined, a compiler warning or
34 // error will be issued if the compiler version exceeds the argument
35 // to BOOST_TESTED_AT(). This can be used to locate workarounds which
36 // may be obsoleted by newer versions.
38 # ifndef BOOST_STRICT_CONFIG
40 # define BOOST_WORKAROUND(symbol, test) \
41 ((symbol != 0) && (1 % (( (symbol test) ) + 1)))
43 // The extra level of parenthesis nesting above, along with the
44 // BOOST_OPEN_PAREN indirection below, is required to satisfy the
45 // broken preprocessor in MWCW 8.3 and earlier.
47 // The basic mechanism works as follows:
48 // (symbol test) + 1 => if (symbol test) then 2 else 1
49 // 1 % ((symbol test) + 1) => if (symbol test) then 1 else 0
51 // The complication with % is for cooperation with BOOST_TESTED_AT().
52 // When "test" is BOOST_TESTED_AT(x) and
53 // BOOST_DETECT_OUTDATED_WORKAROUNDS is #defined,
55 // symbol test => if (symbol <= x) then 1 else -1
56 // (symbol test) + 1 => if (symbol <= x) then 2 else 0
57 // 1 % ((symbol test) + 1) => if (symbol <= x) then 1 else divide-by-zero
60 # ifdef BOOST_DETECT_OUTDATED_WORKAROUNDS
61 # define BOOST_OPEN_PAREN (
62 # define BOOST_TESTED_AT(value) > value) ?(-1): BOOST_OPEN_PAREN 1
64 # define BOOST_TESTED_AT(value) != ((value)-(value))
69 # define BOOST_WORKAROUND(symbol, test) 0
73 #endif // WORKAROUND_DWA2002126_HPP