On Fri, 18 Mar 2022 at 12:47, Rainer Orth wrote: > > Hi Jonathan, > > > I did some very brief testing and it seemed like a program linked to > > the Solaris 11.3 libstdc++.so.6.0.30 (with from_chars@GLIBCXX_3.4.30) > > can still run against libstdc++.so.6.0.30 with > > from_chars@GLIBCXX_3.4.29 (which should match what you get on Solaris > > 11.4 if I correctly fiddled with the versioning). So I don't > > indeed. You can observe the symbols provided and consumed by shared > objects and executables with pvs. > > E.g. on 11.4: > > $ pvs -dsvo libstdc++.so|grep _ZSt10from_charsPKcS0_R > libstdc++.so - GLIBCXX_3.4.29: _ZSt10from_charsPKcS0_RfSt12chars_format; > libstdc++.so - GLIBCXX_3.4.29: _ZSt10from_charsPKcS0_ReSt12chars_format; > libstdc++.so - GLIBCXX_3.4.29: _ZSt10from_charsPKcS0_RdSt12chars_format; > > for the provider side vs. 11.3: > > $ pvs -dsvo libstdc++.so|grep _ZSt10from_charsPKcS0_R > libstdc++.so - GLIBCXX_3.4.30: _ZSt10from_charsPKcS0_ReSt12chars_format; > libstdc++.so - GLIBCXX_3.4.30: _ZSt10from_charsPKcS0_RdSt12chars_format; > libstdc++.so - GLIBCXX_3.4.30: _ZSt10from_charsPKcS0_RfSt12chars_format; > > pvs -r shows symbols and versions required by an executable. > > > understand how the Solaris runtime linker handles symbol versions, but > > it seems like there's no backwards compatibility problem for the > > Solaris 11.4 build of libstdc++.so.6.0.30. > > You can observe this at runtime with LD_DEBUG=versions or > versions,detail. LD_DEBUG=help <some command> gives the full info. > > IIRC Solaris ld.so.1 just checks if the versions required by an > executable are provided by a shared object, but doesn't look into > individual symbols in advance. It may well be that some checks have > been relaxed in the 11.4 timeframe, though.
Ah that would explain it. The libstdc++.so built on Solaris 11.4 has the std::from_chars symbols and it has version GLIBCXX_3.4.30, so that satisfies the requirements for a program linked against the libstdc++.so on Solaris 11.3.
