Re: [Boost-users] [Preprocessor] MSVC nonstandard macro expansion workaround?

Subject: Re: [Boost-users] [Preprocessor] MSVC nonstandard macro expansion workaround?
From: Edward Diener (eldiener_at_[hidden])
Date: 2016-03-04 08:53:10

On 3/4/2016 5:33 AM, Roger Leigh wrote:
> On 03/03/2016 19:37, paul Fultz wrote:
>>> On Thursday, March 3, 2016 7:50 AM, "rleigh_at_[hidden]"
>>> <rleigh_at_[hidden]> wrote:
>
>>> I've been trying to get Boost.Preprocessor to run a nested for loop over
>>> two sequences to output nested switch blocks and case statements.  This
>>> works fine with GCC and clang.  Unfortunately it's broken with MSVC.  If
>>> anyone had any thoughts on what I might need to tweak to enable the code
>>> to work with MSVC, I'd be very appreciative.  Even if it's as nasty as a
>>>
>>
>>> big ifdef with an alternative set of macros!
>>
>>
>> I don't have MSVC available to test this right now, but you could try
>> adding an extra scan and avoid using strange operator combinations as
>> well:
>>
>> BOOST_PP_EXPAND(BOOST_PP_EXPAND(BOOST_PP_SEQ_FOR_EACH(LT_TOPLEVEL,,
>> LASERTYPE_VALUES)));
>>
>> If that doesn't work. Would you be able to post the PP output of what
>> gets expanded inside of main? This would help diagnose the issue,
>> until someone can look at it with MSVC.
>
> With the plain source as I posted: failure to expand a whole set of macros.
>
> test-pp.cpp(22) : warning C4003: not enough actual parameters for macro
> 'BOOST_PP_VARIADIC_ELEM_3'
> test-pp.cpp(22) : warning C4003: not enough actual parameters for macro
> 'BOOST_PP_BOOL'
> test-pp.cpp(22) : warning C4003: not enough actual parameters for macro
> 'BOOST_PP_BOOL_I'
> test-pp.cpp(22) : warning C4003: not enough actual parameters for macro
> 'BOOST_PP_VARIADIC_ELEM_2'
> test-pp.cpp(22) : warning C4003: not enough actual parameters for macro
> 'BOOST_PP_DEC'
> test-pp.cpp(22) : warning C4003: not enough actual parameters for macro
> 'BOOST_PP_DEC_I'
> --------
> enum LaserType
> {
>    EXCIMER, GAS, METALVAPOR, SOLIDSTATE, DYE, SEMICONDUCTOR,
> FREEELECTRON, OTHER
> };
>
> int main() {
> std::cout << "Test toplevel: " << LaserType(EXCIMER ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(3, (LT_NESTED, EXCIMER,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_3, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, EXCIMER,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout << "Test toplevel: " <<
> LaserType(GAS ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(4, (LT_NESTED, GAS,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_4, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, GAS,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout << "Test toplevel: " <<
> LaserType(METALVAPOR ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(5, (LT_NESTED, METALVAPOR,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_5, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, METALVAPOR,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout << "Test toplevel: " <<
> LaserType(SOLIDSTATE ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(6, (LT_NESTED, SOLIDSTATE,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_6, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, SOLIDSTATE,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout
> << "Test toplevel: " << LaserType(DYE ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(7, (LT_NESTED, DYE,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_7, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, DYE,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout << "Test toplevel: " <<
> LaserType(SEMICONDUCTOR ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(8, (LT_NESTED, SEMICONDUCTOR,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_8, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, SEMICONDUCTOR,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout << "Test toplevel: " <<
> LaserType(FREEELECTRON ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(9, (LT_NESTED, FREEELECTRON,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_9, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, FREEELECTRON,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout << "Test toplevel: " <<
> LaserType(OTHER ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(10, (LT_NESTED, OTHER,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_10, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, OTHER,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); ;
> }
> --------
>
>
> With the addition of another BOOST_PP_EXPAND at the top level, I get the
> same except for minor whitespace differences:
>
>   test-pp.cpp(22) : warning C4003: not enough actual parameters for
> macro 'BOOST_PP_VARIADIC_ELEM_3'
> test-pp.cpp(22) : warning C4003: not enough actual parameters for macro
> 'BOOST_PP_BOOL'
> test-pp.cpp(22) : warning C4003: not enough actual parameters for macro
> 'BOOST_PP_BOOL_I'
> test-pp.cpp(22) : warning C4003: not enough actual parameters for macro
> 'BOOST_PP_VARIADIC_ELEM_2'
> test-pp.cpp(22) : warning C4003: not enough actual parameters for macro
> 'BOOST_PP_DEC'
> test-pp.cpp(22) : warning C4003: not enough actual parameters for macro
> 'BOOST_PP_DEC_I'
> --------
> enum LaserType
> {
>    EXCIMER, GAS, METALVAPOR, SOLIDSTATE, DYE, SEMICONDUCTOR,
> FREEELECTRON, OTHER
> };
>
> int main() {
> std::cout << "Test toplevel: " << LaserType(EXCIMER ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(3, (LT_NESTED, EXCIMER,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_3, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, EXCIMER,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout << "Test toplevel: " <<
> LaserType(GAS ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(4, (LT_NESTED, GAS,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_4, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, GAS,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout << "Test toplevel: " <<
> LaserType(METALVAPOR ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(5, (LT_NESTED, METALVAPOR,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_5, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, METALVAPOR,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout << "Test toplevel: " <<
> LaserType(SOLIDSTATE ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(6, (LT_NESTED, SOLIDSTATE,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_6, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, SOLIDSTATE,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout
> << "Test toplevel: " << LaserType(DYE ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(7, (LT_NESTED, DYE,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_7, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, DYE,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout << "Test toplevel: " <<
> LaserType(SEMICONDUCTOR ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(8, (LT_NESTED, SEMICONDUCTOR,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_8, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, SEMICONDUCTOR,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout << "Test toplevel: " <<
> LaserType(FREEELECTRON ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(9, (LT_NESTED, FREEELECTRON,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_9, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, FREEELECTRON,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M); std::cout << "Test toplevel: " <<
> LaserType(OTHER ) << " \n";
> BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_SEQ_FOR_EACH_M,
> BOOST_PP_TUPLE_EAT_2)(10, (LT_NESTED, OTHER,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8)) BOOST_PP_IIF_BOOST_PP_BOOL_(BOOST_PP_FOR_10, BOOST_PP_TUPLE_EAT_4)((
> BOOST_PP_EXPAND(LT_NESTED, OTHER,
> (EXCIMER)(GAS)(METALVAPOR)(SOLIDSTATE)(DYE)(SEMICONDUCTOR)(FREEELECTRON)(OTHER),
> 8), ,
> BOOST_PP_IIF_BOOST_PP_BOOL_BOOST_PP_DEC_(BOOST_PP_SEQ_FOR_EACH_O_I_TAIL,
> BOOST_PP_SEQ_FOR_EACH_O_I_NIL) (), BOOST_PP_DEC_ ),
> BOOST_PP_SEQ_FOR_EACH_P, BOOST_PP_SEQ_FOR_EACH_O,
> BOOST_PP_SEQ_FOR_EACH_M);;
> }
> --------
>
> I've tried changing the expansion in the LT_TOPLEVEL macro with variants
> of PP_DEFER/PP_SEQ_FOR_EACH_R/PP_EXPAND without it making any
> significant difference.  Oh MSVC how I detest thee!

The general problem you are encountering in the VC++ preprocessor is 
that it often re-scans macro expansion when it should not be doing so 
according to the preprocessor rules of standard C++. I give a simple 
example of this in my VMD library doc.

Needless to say the VC++ preprocessor has never been a standard C++ 
conforming preprocessor. What's worse is that Microsoft has never 
provided a tool which shows what the VC++ preprocessor is actually doing 
when it expands a macro, but of course if it ever had it would have 
clearly showed the ways in which it was not C++ standard compliant, 
therefore embarassing Microsoft.