This is a simple clang tool to check for incorrect visibility specifiers
in libc++ headers. If we have a class marked with default visibility, we
want all templated member functions whose definitions are outside the
class declaration to be marked inline and/or hidden visibility, so that
other libraries using the headers and wishing to control their
visibility (using -fvisibility=hidden -fvisibility-inlines-hidden) do
not export implicit instantiations of those template member functions.
The same applies to template classes with explicit instantiation
declarations marked with default visibility. The tool finds member
functions which are not marked appropriately.
This tool was mostly a personal exercise to learn clang tooling infrastructure; I'm uploading it in case anyone else wants to double check my logic or build something similar. It's heavily based on the clang AST visitor example and Eli Bendersky's samples.
You must have a source checkout of llvm, clang, and libc++, and a build of llvm (the libraries and llvm-config) and the clang libraries. Edit the variables at the start of the Makefile to point to the appropriate paths on your system. You must also have compiled lit and FileCheck to run the tests.
Run make bad-visibility-finder to compile the tool, and run it using
./bad-visibility-finder source.cpp --. Run make check to run tests
and make run-bad-visibility-finder (or just make) to run the checker
against all libc++ headers.
I've tested on macOS 10.12 and CentOS 7 against tip of tree llvm as of 4th December 2016. All bets are off on other systems.