Recent libstdc++ regression on i686-linux: abi/cxx_runtime_only_linkage.cc

[Paolo Carlini]

Hi,
> What macro do I switch on? _GLIBCXX_ATOMIC_BUILTINS_4?
Yes, should be safe for static switching. I think you should consider 
also the option of having less stuff exported from libsupc++: if you 
somehow manage to have the different code paths in the headers, then you 
can dynamically switch on |__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4, which 
changes depending on the actual compiler switches (i.e., it's defined if 
on x86_linux, you use -march=i486)|

Anyway, I will be waiting for concrete proposals: also make sure that 
if, on a specific target, parts of N2179 are not available users 
understand it, easily, ideally with a compile-time error.
|||
|Paolo.