Nrthugu

If you compile with -fvisibility=hidden or with msvc you have to export your shared library symbols manually. As an experiment, how could you find them automatically with AST matchers (clang-query)?

It's not that easy as a minimal set of export declarations is desired and things quickly get complicated with inline functions, templates, out-of-line template definitions, static data members, etc.

A general answer in LLVM IR or C++ standard parlance is also welcome.

Not sure about clang-query but if clients of your library use existing public headers you can collect declarations by expecting them via libclang. A simple example of this is given in ShlibVisibilityChecker project (it identifies spurious exports from shared libs).

You should be able to get this information through an AST MatchFinder. A simple matcher like

namedDecl().bind("named_decl")

will match all NamedDecl nodes. Then in the callback, you can get the node's Linkage attribute, and process the node accordingly. A callback that printed out which symbols have external linkage might look something like this:

struct LinkagePrinter : public MatchFinder::Callback {

  void run(MatchResult const & result) override {

    using namespace clang;

    NamedDecl const * n_decl =     

      result.Nodes.getNodeAs<NamedDecl("named_decl");

    if(n_decl){

      Linkage l = n_decl->getLinkage();

      switch(l){

        case ExternalLinkage:

          std::cout << "symbol " << n_decl->getNameAsString() 

             << " has external linkagen";

        // ... etc 

      } 

    } 

    return;

  }

}; // LinkagePrinter

This is roughly right--I haven't checked that this compiles. Register the matcher and callback with a MatchFinder, load the MatchFinder into a Tool, and you should be in business. There are lots of examples in https://github.com/lanl/CoARCT .