Nested macros containing ## do not get expanded properly.

[tortoisedoc]

#define GETMYID(a) ((a))+1
#define FIGHT_FOO(c, ...) foo(c, ##__VA_ARGS__)
FIGHT_FOO(1, GETMYID(a));

The gcc -E says:

foo(1, ((a))+1);

And simplecpp says:

foo ( 1 , GETMYID ( a ) ) ;

[danmar]

For your information.. please always indent all code with 4 spaces. Then github will understand it's code. it will look better and it avoids that code are interpreted as formatting.

[tortoisedoc]

Thanks, not used to github posting too much :). Apologies for the hassle!

[amai2012]

That seems to be a compiler specific extension to the concatenation operator, see http://en.cppreference.com/w/cpp/preprocessor/replace#.23_and_.23.23_operators

[datadiode]

So the C++20 standard way of coding this would be:

#define GETMYID(a) ((a))+1
#define FIGHT_FOO(c, ...) foo(c __VA_OPT__(,) __VA_ARGS__)
FIGHT_FOO(1, GETMYID(a));

This indeed works with simplecpp.

[firewave]

The original case now shows:

1:
2: 
3: foo ( 1 , ( ( a ) ) + 1 ) ;