I have two questions regarding the abi_tag attribute (as documented at
<https://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Attributes.html>):
1 "The attribute can also be applied to an inline namespace, but does
not affect the mangled name of the namespace; in this case it is only
used for -Wabi-tag warnings and automatic tagging of functions and
variables."
I would naively assume that the "automatic tagging" part means that with
inline namespace n __attribute__((__abi_tag__("t"))) { void f() {} }
n::f would be tagged, but that appears not to be the case?
2 "The argument can be a list of strings of arbitrary length."
Does that mean the list can be empty?
void f() __attribute__((__abi_tag__()));
fails with "error: wrong number of arguments specified for ‘__abi_tag__’
attribute" while
inline namespace n __attribute__((__abi_tag__())) {}
is accepted by recent trunk GCC (as well as older versions).
(I stumbled across the latter on Fedora 23, where libstdc++'s
<https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=226022> "Fix
abi_tag in special modes" is not yet fixed, so it contains such an empty
abi_tag on an inline namespace, and Clang with patch
<http://reviews.llvm.org/D12834> "add gcc abi_tag support" produces an
error.)
