Re: [boost] Re: [Config] Testing instructions for compiler vendors

From: David Abrahams (dave_at_[hidden])
Date: 2002-12-18 13:48:00

Gennaro Prota <gennaro_prota_at_[hidden]> writes:

> On Tue, 17 Dec 2002 11:44:12 -0000, "John Maddock"
> <jm_at_[hidden]> wrote:
>
>>Personally I would rather that you stuck to the simplest possible
>>implementation, and for me that outweighs the advantages that using the pp
>>lib might bring.  The recent discussion is all very clever, but I'm not
>>convinced that it really adds anything.
>
> As to possible alternatives, my idea is to use two different macros:
> the BOOST_WORKAROUND version, which Dave has already implemented, and
> another one that doesn't let you specify a test, just the version. The
> point is: what test could the user specify that can be negated without
> giving unwanted errors when detection of outdated workarounds is
> enabled? Basically, only <= (For instance: if you specify == 0x600,
> you just risk to get an error when testing with version 0x500). That
> considered, I would say: let him just specify the version with
> something like
>
>  #define ERROR(cond) (1 / (cond? 0 : 1))
>  #define WORKAROUND_WITH_CHECK(symbol, version) (           \
>         ((symbol) != 0)                                     \
>         && ERROR(DETECT_OUTDATED && (symbol > version) )    \
>                   )
>

I'd much prefer:
    BOOST_WORKAROUND(__SUNPRO_CC, BOOST_LATEST_VERSION(0x530))

Which I think is easily achievable, no?

    # define BOOST_WORKAROUND(symbol, test)  (symbol != 0) && (1 % ((symbol test) + 1))
    # ifdef BOOST_DETECT_OUTDATED
    #  define BOOST_LATEST_VERSION(value)  >value?-1:1
    # else
    #  define BOOST_LATEST_VERSION(value) != 0
    # endif 

    int x = 0;

    # if BOOST_WORKAROUND(COMPILER_VERSION, < 20)
    int y = 0;
    # elif BOOST_WORKAROUND(COMPILER_VERSION, BOOST_LATEST_VERSION(20))
    int z = 0;
    # endif 

This seems to work for everything but metrowerks, which says:

    ### mwcc Compiler:
    #    File: foo.cpp
    # ----------------
    #      16: ( 21 != 0) && (1 % (( 21  >20?-1:1) + 1))
    #   Error: ^
    #   expression syntax error

:(

If anyone can come up with a workaround, I'd be psyched!

-- 
                       David Abrahams
   dave_at_[hidden] * http://www.boost-consulting.com
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