GNU Visibility Attribute
When going through the folly [https://github.com/facebook/folly] code base, sometimes, you see definitions like class FOLLY_EXPORT OptionalEmptyException : public std::runtime_error { ... FOLLY_EXPORT is defined as #define FOLLY_EXPORT __attribute__((__visibility__("default"))) It sets the visibility attribute of symbol OptionalEmptyException to "default". What does it do…