[boost] [wave) experiences

From: Vambola Kotkas (vambola.kotkas_at_[hidden])
Date: 2005-12-03 23:22:08

Wave Driver C++ preprocessor seems quite useful tool to see what happens 
with most macros. Unfortunatelly it needs some debugging before it can be 
used to preprocess real code. For example it refuses (unneccessarily) to 
process sometimes.

Silly example 1:
 #if __LINE__ == 11112223334
#pragma message( "Huh!" )
 #endif
Result:
 test.cpp(1): error: ill formed integer literal or integer constant too 
large: 11112223334.

None of the available wave  flags did seemingly help. Not that i need huge 
integers, however boost sometimes does have way bigger ones so it must be 
legal? MS Visual C++ 7.1 processes constants like 18446744073709551615 
without any noise.
See ... 1.33.0 boost/cstdint.hpp  line(263):
# if ULONG_MAX == 18446744073709551615 // 2**64 - 1

Silly example 2:
#define SHOW2(x) #x
#define SHOW(x) SHOW2(Number is:##x)
#pragma message( SHOW(__LINE__))
Result:
test.cpp(3): error: pasting the following two tokens does not give a valid 
preprocessing token: ":" and "__LINE__"
Maybe its buggy and MS made its preprocessor too lousy there  ... just for 
reference Visual C++ 7.1 preprocess result:

#line 1 "c:\\develop\\vc7test\\test.cpp"

#pragma message( "Number is:3")

Thing to note is that removing the colon from line 2 produces wave output 
with contents:
#line 3 "test.cpp"
#pragma message("Number is__LINE__")

Side question: How to force wave to use full paths in #line directives? 
Larger projects may contain similarily named files and people usually have 
multiple versions of their own software, nothing to talk of libraries and 
SDK-s. Silly thing 2 can be transformed into Working thing 2:
#define SHOW2(x) #x
#define SHOW(x) SHOW2(x)
#pragma message("Number is:" SHOW(__LINE__))
Wave produces same output as VC++ 7.1 then:
#line 3 "test.cpp"
#pragma message("Number is:" "3")

Finally ... fair test for preprocessor is if it preprocesses its own code. 
That makes wave to crash with "unexpected exception caught." Various sets 
of -P and -D options make it to crash in various places. I did not manage to 
find a good set of options so it does not crash. How to compile debug 
version of wave with vc7.1?  Without  debugging it is hard to further track 
down what is going on there. I tried the wave in boost 1.33.0.
Thanks.