Visual C++ too-few/many args warnings for APPLY macro expansion

A

Alf P. Steinbach

Doing a macro to add "L" in front of each string literal in a sequence
(i.e. compile time concatenation) of such literals.

The following code works nicely with g++, but Visual C++ emits two warnings:

[D:\dev\test]
cl apply.cpp /Feb
Click to expand...
apply.cpp
apply.cpp(78) : warning C4002: too many actual parameters for macro 'PUFFUP'
apply.cpp(78) : warning C4003: not enough actual parameters for macro
'PUFFUP'

[D:\dev\test]
_
Click to expand...

Here's the code:

Code: 
/*
* The PP_NARG macro evaluates to the number of arguments that have been
* passed to it.
*
* Laurent Deniau, "__VA_NARG__," 17 January 2006, <comp.std.c> (29
November 2007).
* https://groups.google.com/forum/?fromgroups=#!topic/comp.std.c/d-6Mj5Lko_s
*/

// Added workaround for silly MSVC bug that yields "too few parameters"
warning.
// - Alf

#define PP_ARG_N( \
_1, _2, _3, _4, _5, _6, _7, _8, _9,_10, \
_11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \
_21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \
_31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \
_41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \
_51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \
_61,_62,_63,N,...) N

#define PP_RSEQ_N() \
63,62,61,60, \
59,58,57,56,55,54,53,52,51,50, \
49,48,47,46,45,44,43,42,41,40, \
39,38,37,36,35,34,33,32,31,30, \
29,28,27,26,25,24,23,22,21,20, \
19,18,17,16,15,14,13,12,11,10, \
9,8,7,6,5,4,3,2,1,0

#ifdef PP_USE_ORIGINAL_DEFINITION
#define PP_NARG_(...) PP_ARG_N( __VA_ARGS__ )
#define PP_NARG( ...) PP_NARG_( __VA_ARGS__, PP_RSEQ_N() )
#else
#define CPPX_INVOKE( macro, args ) macro args       // For Visual C++.
#define CPPX_INVOKE_B( macro, args ) macro args     // Then for g++...

#define CPPX_CONCAT__( a, b )       a ## b
#define CPPX_CONCAT_( a, b )        CPPX_CONCAT__( a, b )
#define CPPX_CONCAT( a, b )         CPPX_CONCAT_( a, b )

#define PP_NARG_AUX(...) CPPX_INVOKE( PP_ARG_N, (__VA_ARGS__) )
#define PP_NARG(...) PP_NARG_AUX( __VA_ARGS__, PP_RSEQ_N() )

#define CPPX_NARGS( ... ) PP_NARG( __VA_ARGS__ )
#endif

#define CPPX_APPLY_1( macroname, arg ) \
CPPX_INVOKE_B( macroname, (arg) )

#define CPPX_APPLY_2( macroname, arg, ... ) \
CPPX_INVOKE_B( macroname, (arg) ) \
CPPX_APPLY_1( macroname, __VA_ARGS__ )

#define CPPX_APPLY_3( macroname, arg, ... ) \
CPPX_INVOKE_B( macroname, (arg) ) \
CPPX_APPLY_2( macroname, __VA_ARGS__ )

#define CPPX_APPLY_4( macroname, arg, ... ) \
CPPX_INVOKE_B( macroname, (arg) ) \
CPPX_APPLY_3( macroname, __VA_ARGS__ )

#define CPPX_APPLY_5( macroname, arg, ... ) \
CPPX_INVOKE_B( macroname, (arg) ) \
CPPX_APPLY_4( macroname, __VA_ARGS__ )

#define CPPX_APPLY( macroname, ... ) \
CPPX_INVOKE( \
CPPX_CONCAT( CPPX_APPLY_, CPPX_NARGS( __VA_ARGS__ ) ), \
( macroname, __VA_ARGS__ ) \
)

#define PUFFUP( arg ) #arg "! "

#include <iostream>
using namespace std;
auto main() -> int
{
cout << CPPX_APPLY( PUFFUP, 4, 5, 6 ) << endl;
}

I wrote the comment about workaround for "too few parameters" many years
ago, and now I can't remember what the Visual C++ bug was. :-(

Any insight or solution other than disabling the warnings?


Cheers,

- Alf
 
A

Alf P. Steinbach

Doing a macro to add "L" in front of each string literal in a sequence
(i.e. compile time concatenation) of such literals.

The following code works nicely with g++, but Visual C++ emits two
warnings:

[D:\dev\test]
cl apply.cpp /Feb
Click to expand...
apply.cpp
apply.cpp(78) : warning C4002: too many actual parameters for macro
'PUFFUP'
apply.cpp(78) : warning C4003: not enough actual parameters for macro
'PUFFUP'

[D:\dev\test]
_
Click to expand...

Here's the code:

Code: 
/*
* The PP_NARG macro evaluates to the number of arguments that have been
* passed to it.
*
* Laurent Deniau, "__VA_NARG__," 17 January 2006, <comp.std.c> (29
November 2007).
*
https://groups.google.com/forum/?fromgroups=#!topic/comp.std.c/d-6Mj5Lko_s
*/

// Added workaround for silly MSVC bug that yields "too few parameters"
warning.
// - Alf

#define PP_ARG_N( \
_1, _2, _3, _4, _5, _6, _7, _8, _9,_10, \
_11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \
_21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \
_31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \
_41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \
_51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \
_61,_62,_63,N,...) N

#define PP_RSEQ_N() \
63,62,61,60, \
59,58,57,56,55,54,53,52,51,50, \
49,48,47,46,45,44,43,42,41,40, \
39,38,37,36,35,34,33,32,31,30, \
29,28,27,26,25,24,23,22,21,20, \
19,18,17,16,15,14,13,12,11,10, \
9,8,7,6,5,4,3,2,1,0

#ifdef PP_USE_ORIGINAL_DEFINITION
#define PP_NARG_(...) PP_ARG_N( __VA_ARGS__ )
#define PP_NARG( ...) PP_NARG_( __VA_ARGS__, PP_RSEQ_N() )
#else
#define CPPX_INVOKE( macro, args ) macro args       // For Visual C++.
#define CPPX_INVOKE_B( macro, args ) macro args     // Then for g++...

#define CPPX_CONCAT__( a, b )       a ## b
#define CPPX_CONCAT_( a, b )        CPPX_CONCAT__( a, b )
#define CPPX_CONCAT( a, b )         CPPX_CONCAT_( a, b )

#define PP_NARG_AUX(...) CPPX_INVOKE( PP_ARG_N, (__VA_ARGS__) )
#define PP_NARG(...) PP_NARG_AUX( __VA_ARGS__, PP_RSEQ_N() )

#define CPPX_NARGS( ... ) PP_NARG( __VA_ARGS__ )
#endif

#define CPPX_APPLY_1( macroname, arg ) \
CPPX_INVOKE_B( macroname, (arg) )

#define CPPX_APPLY_2( macroname, arg, ... ) \
CPPX_INVOKE_B( macroname, (arg) ) \
CPPX_APPLY_1( macroname, __VA_ARGS__ )

#define CPPX_APPLY_3( macroname, arg, ... ) \
CPPX_INVOKE_B( macroname, (arg) ) \
CPPX_APPLY_2( macroname, __VA_ARGS__ )

#define CPPX_APPLY_4( macroname, arg, ... ) \
CPPX_INVOKE_B( macroname, (arg) ) \
CPPX_APPLY_3( macroname, __VA_ARGS__ )

#define CPPX_APPLY_5( macroname, arg, ... ) \
CPPX_INVOKE_B( macroname, (arg) ) \
CPPX_APPLY_4( macroname, __VA_ARGS__ )

#define CPPX_APPLY( macroname, ... ) \
CPPX_INVOKE( \
CPPX_CONCAT( CPPX_APPLY_, CPPX_NARGS( __VA_ARGS__ ) ), \
( macroname, __VA_ARGS__ ) \
)

#define PUFFUP( arg ) #arg "! "

#include <iostream>
using namespace std;
auto main() -> int
{
cout << CPPX_APPLY( PUFFUP, 4, 5, 6 ) << endl;
}

I wrote the comment about workaround for "too few parameters" many years
ago, and now I can't remember what the Visual C++ bug was. :-(

Any insight or solution other than disabling the warnings?
Click to expand...

A pretty awkward solution, but it works:

Code: 
/*
* The PP_NARG macro evaluates to the number of arguments that have been
* passed to it.
*
* Laurent Deniau, "__VA_NARG__," 17 January 2006, <comp.std.c> (29
November 2007).
* https://groups.google.com/forum/?fromgroups=#!topic/comp.std.c/d-6Mj5Lko_s
*/

// Added workaround for silly MSVC bug that yields "too few parameters"
warning.
// - Alf

#define PP_ARG_N( \
_1, _2, _3, _4, _5, _6, _7, _8, _9,_10, \
_11,_12,_13,_14,_15,_16,_17,_18,_19,_20, \
_21,_22,_23,_24,_25,_26,_27,_28,_29,_30, \
_31,_32,_33,_34,_35,_36,_37,_38,_39,_40, \
_41,_42,_43,_44,_45,_46,_47,_48,_49,_50, \
_51,_52,_53,_54,_55,_56,_57,_58,_59,_60, \
_61,_62,_63,N,...) N

#define PP_RSEQ_N() \
63,62,61,60, \
59,58,57,56,55,54,53,52,51,50, \
49,48,47,46,45,44,43,42,41,40, \
39,38,37,36,35,34,33,32,31,30, \
29,28,27,26,25,24,23,22,21,20, \
19,18,17,16,15,14,13,12,11,10, \
9,8,7,6,5,4,3,2,1,0

#ifdef PP_USE_ORIGINAL_DEFINITION
#define PP_NARG_(...) PP_ARG_N( __VA_ARGS__ )
#define PP_NARG( ...) PP_NARG_( __VA_ARGS__, PP_RSEQ_N() )
#else
#define CPPX_INVOKE( macro, args ) macro args       // For Visual C++.
#define CPPX_INVOKE_B( macro, args ) macro args     // Then for g++...

#define CPPX_CONCAT__( a, b )       a ## b
#define CPPX_CONCAT_( a, b )        CPPX_CONCAT__( a, b )
#define CPPX_CONCAT( a, b )         CPPX_CONCAT_( a, b )

#define PP_NARG_AUX(...) CPPX_INVOKE( PP_ARG_N, (__VA_ARGS__) )
#define PP_NARG(...) PP_NARG_AUX( __VA_ARGS__, PP_RSEQ_N() )

#define CPPX_NARGS( ... ) PP_NARG( __VA_ARGS__ )
#endif

#define CPPX_APPLY_1( macroname, a1 ) \
CPPX_INVOKE_B( macroname, (a1) )

#define CPPX_APPLY_2( macroname, a1, a2 ) \
CPPX_INVOKE_B( macroname, (a1) ) \
CPPX_APPLY_1( macroname, a2 )

#define CPPX_APPLY_3( macroname, a1, a2, a3 ) \
CPPX_INVOKE_B( macroname, (a1) ) \
CPPX_APPLY_2( macroname, a2, a3 )

#define CPPX_APPLY_4( macroname, a1, a2, a3, a4 ) \
CPPX_INVOKE_B( macroname, (a1) ) \
CPPX_APPLY_3( macroname, a2, a3, a4 )

#define CPPX_APPLY_5( macroname, a1, a2, a3, a4, a5 ) \
CPPX_INVOKE_B( macroname, (a1) ) \
CPPX_APPLY_4( macroname, a2, a3, a4, a5 )

#define CPPX_APPLY_6( macroname, a1, a2, a3, a4, a5, a6 ) \
CPPX_INVOKE_B( macroname, (a1) ) \
CPPX_APPLY_5( macroname, a2, a3, a4, a5, a6 )

#define CPPX_APPLY_7( macroname, a1, a2, a3, a4, a5, a6, a7 ) \
CPPX_INVOKE_B( macroname, (a1) ) \
CPPX_APPLY_6( macroname, a2, a3, a4, a5, a6, a7 )

#define CPPX_APPLY_8( macroname, a1, a2, a3, a4, a5, a6, a7, a8 ) \
CPPX_INVOKE_B( macroname, (a1) ) \
CPPX_APPLY_7( macroname, a2, a3, a4, a5, a6, a7, a8 )

#define CPPX_APPLY_9( macroname, a1, a2, a3, a4, a5, a6, a7, a8, a9 ) \
CPPX_INVOKE_B( macroname, (a1) ) \
CPPX_APPLY_8( macroname, a2, a3, a4, a5, a6, a7, a8, a9 )

#define CPPX_APPLY_10( macroname, a1, a2, a3, a4, a5, a6, a7, a8, a9,
a10 ) \
CPPX_INVOKE_B( macroname, (a1) ) \
CPPX_APPLY_9( macroname, a2, a3, a4, a5, a6, a7, a8, a9, a10 )

#define CPPX_APPLY_11( macroname, a1, a2, a3, a4, a5, a6, a7, a8, a9,
a10, a11 ) \
CPPX_INVOKE_B( macroname, (a1) ) \
CPPX_APPLY_10( macroname, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11 )

#define CPPX_APPLY_12( macroname, a1, a2, a3, a4, a5, a6, a7, a8, a9,
a10, a11, a12 ) \
CPPX_INVOKE_B( macroname, (a1) ) \
CPPX_APPLY_11( macroname, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11,
a12 )

#define CPPX_APPLY( macroname, ... ) \
CPPX_INVOKE( \
CPPX_CONCAT( CPPX_APPLY_, CPPX_NARGS( __VA_ARGS__ ) ), \
( macroname, __VA_ARGS__ ) \
)

#define PUFFUP( arg ) #arg "! "

#include <iostream>
using namespace std;
auto main() -> int
{
cout << CPPX_APPLY( PUFFUP, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 )
<< endl;
}

- Alf
 

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