[PATCH v2] New mechanism for declaring const-covariant string functions.

[Florian Weimer]

On 11/21/2016 06:46 PM, Zack Weinberg wrote:

> diff --git a/string/bits/const-covariance.h b/string/bits/const-covariance.h
> +#define __CC_VA_NARGS(...)  __CC_VA_NARGS_(__VA_ARGS__, __CC_RSEQ)
> +#define __CC_VA_NARGS_(...) __CC_VA_NARGS__(__VA_ARGS__)
> +#define __CC_VA_NARGS__(_1, _2, _3, _4, _5, _6, _7, _8, N, ...) N
> +#define __CC_RSEQ 8, 7, 6, 5, 4, 3, 2, 1

It's not clear to me what ensures that variadic macros are available at 
this point.  <bits/const-covariance.h> seems to be included 
unconditionally, not just for GNU or C++11.  I don't think you can use 
variadic macros for this.

Florian