[Bug c++/87947] Symbol Does Not Appear in Object File

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87947

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
That answer is about whether it's "safe", and explains that the -std options do
not create ABI incompatibilities. The question is also stated as (emphasis in
the original):

> For simplicity, let's assume all headers were written in C++11, **using only constructs whose semantics haven't changed between all three standard versions**.

This is a feature whose semantics changed. What you're seeing is pretty much
required behaviour for a correct implementation, not an ABI incompatibility
introduced by GCC.