https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109054
Bug ID: 109054 Summary: _Unwind_GetLanguageSpecificData should have protected visibility Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: libgcc Assignee: unassigned at gcc dot gnu.org Reporter: woodard at redhat dot com Target Milestone: --- When you look at libgcc_s.so's implementation of _Unwind_GetLanguageSpecificData $ eu-readelf -s /lib64/libgcc_s.so.1 | grep _Unwind_GetLanguageSpecificData 67: 0000000000014d20 12 FUNC GLOBAL DEFAULT 14 _Unwind_GetLanguageSpecificData@@GCC_3.0 It has default visibility. Yes I know that a library should not export functions that are _[A-Z] because those are reserved for system libraries. ref: http://eel.is/c++draft/lex.name#3.1 However, libunwind does and this led to a very hard to track down problem when they had linked an application a particular way. What happened was libgcc_s.so picked up libunwind's implementation of _Unwind_GetLanguageSpecificData this ultimately caused libgcc_s.so to not be able to find the LSDA of an object throwing an exception. This made it so that there was no way to catch the exception and therefore the application aborted. The application was not even aware of the fact that they were using libunwind becasue it came in as a dependency of libzmq. I can't think of a good reason why libgcc_s.so should allow another library to replace its version of _Unwind_GetLanguageSpecificData and so it seems to me that the symbol's visibility should be made protected rather than having the default visibility. Other related bugs are: https://bugzilla.redhat.com/show_bug.cgi?id=2175966