https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107535
Bug ID: 107535 Summary: Shouldn't -fvisibility=hidden hide C++17 inline static variables? Product: gcc Version: 11.3.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ Assignee: unassigned at gcc dot gnu.org Reporter: junchao.zhang at gmail dot com Target Milestone: --- I think inline static variables are global. However, they could be hidden by -fvisibility=hidden. This is dangerous, since with C++17 inline static variables, they will appear in headers and be included in *.cpp files. If the *.cpp files are compiled with -fvisibility=hidden, each will get their own storage. $ cat foo.hpp struct Foo {static inline int s = 100; }; extern __attribute__ ((visibility ("default"))) void DumpLibFoo(); $ cat foo.cpp #include <stdio.h> #include <foo.hpp> void DumpLibFoo() { printf("In libfoo, Foo::s (%p) = %d\n", &Foo::s, Foo::s); } $ cat test.cpp #include <stdio.h> #include <foo.hpp> int main() { Foo::s = 200; printf("In main, Foo::s (%p) = %d\n", &Foo::s, Foo::s); DumpLibFoo(); return 0; } ----- gcc -std=c++17 -c -fPIC -I./ test.cpp -fvisibility=hidden gcc -std=c++17 -c -fPIC -I./ foo.cpp gcc -o libfoo.so -shared foo.o gcc -std=c++17 -o test test.o -Wl,-rpath ./ -L ./ -lfoo ./test In main, Foo::s (0x5604c2741010) = 200 In libfoo, Foo::s (0x7f4e5173d028) = 100