https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33877
--- Comment #9 from Alejandro Colomar <foss+...@alejandro-colomar.es> ---
GCC's ## __VA_ARGS__ seems to differ from __VA_OPT__(), and seems to agree with
the more intuitive interpretation of number of arguments.
alx@debian:~/tmp$ cat vo.c | nl -ba
1 #define foo(...) __LINE__: foo: __VA_OPT__(nonzero args:
__VA_ARGS__)
2 #define bar(a, ...) __LINE__: bar: __VA_OPT__(nonzero args:
__VA_ARGS__)
3
4 foo()
5 foo(x)
6 foo(,)
7
8 bar(a)
9 bar(a,)
10 bar(a,b)
11
12 #define f(...) __LINE__: f:, ## __VA_ARGS__
13 #define b(a, ...) __LINE__: b:, ## __VA_ARGS__
14
15 f()
16 f(x)
17 f(,)
18
19 b(a)
20 b(a,)
21 b(a,b)
alx@debian:~/tmp$ g++ -E vo.c | grep -v ^# | uniq
4: foo:
5: foo: nonzero args: x
6: foo: nonzero args: ,
8: bar:
9: bar:
10: bar: nonzero args: b
15: f:
16: f:,x
17: f:,,
19: b:
20: b:,
21: b:,b
GCC's ## __VA_ARGS__ seems to consider that lines 15 and 19 get 0 arguments,
while all others get one or more. I think __VA_OPT__() is badly specified in
the standard and should be fixed.
