[libc++] Mark string operator+ _LIBCPP_FUNC_VIS
It has an extern template instantiation declaration in the headers and a
corresponding instantiation definition in the library, so we must mark
it with _LIBCPP_FUNC_VIS to make it available outside the library.
This doesn't cause any ABI changes as-is since we don't build libc++
with hidden visibility (so the function is exported anyway). It's needed
for building libc++ with hidden visibility, however.
Clarify the Windows behavior for extern function templates while I'm
here, since this exercises that behavior.
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@307966 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/docs/DesignDocs/VisibilityMacros.rst b/docs/DesignDocs/VisibilityMacros.rst
index 20665cd..d02d2df 100644
--- a/docs/DesignDocs/VisibilityMacros.rst
+++ b/docs/DesignDocs/VisibilityMacros.rst
@@ -98,7 +98,8 @@
explicit instantiations themselves are marked as exported. Note that this
applies *only* to extern *class* templates. Extern *function* templates obey
regular import/export semantics, and applying `dllexport` directly to the
- extern template declaration is the correct thing to do for them.
+ extern template declaration (i.e. using `_LIBCPP_FUNC_VIS`) is the correct
+ thing to do for them.
**_LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS**
Mark the member functions, typeinfo, and vtable of an explicit instantiation
diff --git a/include/string b/include/string
index 010a4c7..97fb4a1 100644
--- a/include/string
+++ b/include/string
@@ -4006,7 +4006,7 @@
_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_string<char>)
_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_string<wchar_t>)
-_LIBCPP_EXTERN_TEMPLATE(string operator+<char, char_traits<char>, allocator<char> >(char const*, string const&))
+_LIBCPP_EXTERN_TEMPLATE(_LIBCPP_FUNC_VIS string operator+<char, char_traits<char>, allocator<char> >(char const*, string const&))
#if _LIBCPP_STD_VER > 11
// Literal suffixes for basic_string [basic.string.literals]