[cfe-users] Porting preprocessor macros to be compatible with clang

[Forumer 4umer via cfe-users]

Hello,

I am sorry to ask for some help on this subject but I am not very 
comfortable with preprocessor and especially with the differences 
between compilers.
We have some (ugly) macros used to generate some data structures and 
methods that works fine on Visual but I would like to use clang to get 
better errors messages

and to compare the compilation time.
So I have created a repository to reproduce the problem and if someone 
could give me some help...
There is only one cpp file so a simple clang++ TestClang.cpp is enough 
to reproduce.

The repository is here: https://github.com/vrichomme/FixMacroOnClang.git

Thanks.
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Re: [cfe-users] Porting preprocessor macros to be compatible with clang

[Forumer 4umer via cfe-users]

So a bit more explanation, the macros are used to generate data 
structure and methods and the following definition is used to declare a 
structure:


DEF_STRUCT(namedDate, namedDate, (std::string, name), (std::time_t, 
date))


On visual when I look at preprocessed file I get this (focus on line 
starting with struct namedDate) :


namespace LibTech
{
   namespace DataTypes
   {
  #line 1 "E:\\DEV\\FixMacroOnClang\\DeclareDatatypes.h"
  #line 17 "E:\\DEV\\FixMacroOnClang\\DeclareDatatypes.h"
  #line 12 "E:\\DEV\\FixMacroOnClang\\Protocol.h"
  #line 1 "E:\\DEV\\FixMacroOnClang\\DataTypesDef.h"

struct namedDate{ std::string name; std::time_t date; };

  #line 13 "E:\\DEV\\FixMacroOnClang\\Protocol.h"
  #line 1 "E:\\DEV\\FixMacroOnClang\\DeclareDatatypes.h"
  #line 1 "E:\\DEV\\FixMacroOnClang\\macro\\UndefDataTypesDef.h"
  #line 14 "E:\\DEV\\FixMacroOnClang\\DeclareDatatypes.h"
  #line 17 "E:\\DEV\\FixMacroOnClang\\DeclareDatatypes.h"
  #line 14 "E:\\DEV\\FixMacroOnClang\\Protocol.h"
   }

}

but when using clang I have this:

namespace LibTech
{
   namespace DataTypes
   {
  # 1 "E:\\DEV\\FixMacroOnClang/DeclareDatatypes.h" 1
  # 12 "E:\\DEV\\FixMacroOnClang/Protocol.h" 2
  # 1 "E:\\DEV\\FixMacroOnClang/DataTypesDef.h" 1

struct namedDate{ PP_GS 2 (TO_FIELD, (std::string, name), (std::time_t, 
date)) };


  # 13 "E:\\DEV\\FixMacroOnClang/Protocol.h" 2
  # 1 "E:\\DEV\\FixMacroOnClang/DeclareDatatypes.h" 1
  # 13 "E:\\DEV\\FixMacroOnClang/DeclareDatatypes.h"
  # 1 "E:\\DEV\\FixMacroOnClang/./macro/UndefDataTypesDef.h" 1
  # 14 "E:\\DEV\\FixMacroOnClang/DeclareDatatypes.h" 2
  # 14 "E:\\DEV\\FixMacroOnClang/Protocol.h" 2
 }
}

as you can see the macros used inside preprocessor.h doesn't work with 
clang I have macro PP_GS and TO_FIELD macros that are not expanded.


I cannot copy/paste all macro definitions because it won't be very easy 
to read but here is how it starts:


#ifndef DEF_ID_BEGIN

//...

#define TO_FIELD(type, name) type name;
#define DEF_STRUCT(type, dataTypeId, ...) struct type{ 
PP_FOREACH_GROUP(TO_FIELD,__VA_ARGS__) };


#else

#include "./macro/UndefDataTypesDef.h"
#undef TO_FIELD

#endif

and inside preprocessor.h

#define PP_PREFIX(Method) PP_##Method
#define PP_SUFFIX(N) N
#define PP_ENTRY(Method,N) PP_PREFIX(Method)PP_SUFFIX(N)
#define PP_CALL_PP_SN( Method, Func, N, ...) PP_ENTRY(Method,N) 
PP_FW(Func, __VA_ARGS__)


#define PP_FOREACH(Func, ...) PP_CALL_PP_SN( S, Func, PP_ARGCOUNT 
PP_FW(__VA_ARGS__), __VA_ARGS__ )
#define PP_FOREACH_GROUP(Func, ...) PP_CALL_PP_SN( GS, Func, PP_ARGCOUNT 
PP_FW(__VA_ARGS__), __VA_ARGS__ )



#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

#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_FW(...) (__VA_ARGS__)
#define PP_NARG_(...) PP_ARG_N PP_FW(__VA_ARGS__)
#define PP_ARGCOUNT(...) PP_NARG_(__VA_ARGS__,PP_RSEQ_N())

but have a look here to see all the macros: 
https://github.com/vrichomme/FixMacroOnClang/blob/master/preprocessor.h


Maybe one of the problem is with PP_FW(...) but not sure about that...

Thanks

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