[RFC PATCH] Use anonymous union for siginfo_t

[Joseph Myers]

On Fri, 11 Aug 2017, Zack Weinberg wrote:

> +* Some headers now make unconditional use of the C2011 'anonymous union'
> +  feature.  In order to compile a program that uses any of these headers,

This is not entirely new.  sysdeps/gnu/netinet/tcp.h has used this feature 
(inside __extension__) since the _BSD_SOURCE removal, to reconcile two 
different APIs for the same structure.  There are probably other uses.  
(sysdeps/unix/sysv/linux/alpha/bits/stat.h has one conditioned on 
__GNUC_PREREQ(3,3), where those conditions could be removed if we agree 
this feature is unconditionally required for using glibc headers.)

-- 
Joseph S. Myers
joseph@codesourcery.com