[libc++] Always build with -fvisibility=hidden

Summary:
This avoids symbols being accidentally exported from the dylib when they
shouldn't. The next step is to use a pragma to apply hidden visibility
to all declarations (unless otherwise specified), which will allow us
to drop the per-declaration hidden visibility attributes we currently
have.

This also has the nice side effect of making sure the dylib exports the
same symbols regardless of the optimization level.

PR38138

Reviewers: EricWF, mclow.lists

Subscribers: mgorny, christof, jkorous, dexonsmith, libcxx-commits

Tags: #libc

Differential Revision: https://reviews.llvm.org/D62868

llvm-svn: 368703

libcxx/include/chrono

@@ -2934,6 +2934,7 @@ struct _FilesystemClock {
   typedef chrono::duration<rep, period> duration;
   typedef chrono::time_point<_FilesystemClock> time_point;
 
+  _LIBCPP_EXPORTED_FROM_ABI
   static _LIBCPP_CONSTEXPR_AFTER_CXX11 const bool is_steady = false;
 
   _LIBCPP_AVAILABILITY_FILESYSTEM _LIBCPP_FUNC_VIS static time_point now() noexcept;

libcxx/include/filesystem

@@ -2583,6 +2583,7 @@ public:
   void disable_recursion_pending() { __rec_ = false; }
 
 private:
+  _LIBCPP_FUNC_VIS
   recursive_directory_iterator(const path& __p, directory_options __opt,
                                error_code* __ec);
 

libcxx/src/CMakeLists.txt

@@ -204,6 +204,7 @@ function(cxx_set_common_defines name)
   if(LIBCXX_CXX_ABI_HEADER_TARGET)
     add_dependencies(${name} ${LIBCXX_CXX_ABI_HEADER_TARGET})
   endif()
+  target_compile_options(${name} PRIVATE -fvisibility=hidden)
   if(WIN32 AND NOT MINGW)
     target_compile_definitions(${name}
                                PRIVATE
@@ -355,7 +356,6 @@ if (LIBCXX_ENABLE_STATIC)
   cxx_set_common_defines(cxx_static)
 
   if (LIBCXX_HERMETIC_STATIC_LIBRARY)
-    append_flags_if_supported(CXX_STATIC_LIBRARY_FLAGS -fvisibility=hidden)
     # If the hermetic library doesn't define the operator new/delete functions
     # then its code shouldn't declare them with hidden visibility.  They might
     # actually be provided by a shared library at link time.

libcxx/src/valarray.cpp

@@ -12,8 +12,8 @@ _LIBCPP_BEGIN_NAMESPACE_STD
 
 // These two symbols are part of the v1 ABI but not part of the >=v2 ABI.
 #if _LIBCPP_ABI_VERSION == 1
-template valarray<size_t>::valarray(size_t);
-template valarray<size_t>::~valarray();
+template _LIBCPP_FUNC_VIS valarray<size_t>::valarray(size_t);
+template _LIBCPP_FUNC_VIS valarray<size_t>::~valarray();
 #endif
 
 template void valarray<size_t>::resize(size_t, size_t);