[Bug libstdc++/66438] libstdc++ 5.1 broke binary compat with old code using std::error_category

[foom at fuhm dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66438

James Y Knight <foom at fuhm dot net> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |UNCONFIRMED
         Resolution|INVALID                     |---

--- Comment #5 from James Y Knight <foom at fuhm dot net> ---
Sorry, please try again.

Andreas Schwab: I did compile it with the libstdc++ that came with the compiler
-- and then I upgraded the binary libstdc++.so to the newer one that came with
gcc 5. And it broken. Thus the report of breaking binary compat. (It also
happens with new compiles in Debian because of what Gianfranco says)

Andrew Pinski:

The *one and only purpose* of the file
libstdc++-v3/src/c++11/compatibility-c++0x.cc is to provide binary
compatibility for c++11 binaries compiled against older libstdc++ versions, and
now running against a newer one.

If libstdc++.so.6, version 5.1, is not supposed to work properly with c++
binaries compiled by the 4.9 compiler, it should not be providing these
compatibility symbols at all.

Since it does provide them, there is clearly intent to provide compatibility
so, it ought to work. Or they should be deleted...