[v3] libstdc++/26142

[Gabriel Dos Reis]

Benjamin Kosnik <bkoz@redhat.com> writes:

| This reverts to previous behavior. In this case, the top level
| __gnu_debug namespace is composed of std::debug and
| __gnu_cxx::debug.  It's assumed that users could similarly create
| their own ::debug namespace. 

So we assume we reserve the name "debug"?  
I mean, do we document that 

    #define debug 0
    #include <header-with-debug-behaviour>


is invalid as far as libstdc++ is concerned?

-- Gaby