smeenai created this revision.
smeenai added reviewers: compnerd, EricWF, mclow.lists.
smeenai added a subscriber: cfe-commits.
On Windows, marking an `extern template class` declaration as exported
actually forces an instantiation, which is not the desired behavior.
Instead, the actual explicit instantiations need to be exported.
https://reviews.llvm.org/D24679
Files:
docs/DesignDocs/VisibilityMacros.rst
include/__config
src/ios.cpp
src/locale.cpp
src/string.cpp
Index: src/string.cpp
===================================================================
--- src/string.cpp
+++ src/string.cpp
@@ -20,10 +20,10 @@
_LIBCPP_BEGIN_NAMESPACE_STD
-template class __basic_string_common<true>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __basic_string_common<true>;
-template class basic_string<char>;
-template class basic_string<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_string<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_string<wchar_t>;
template
string
Index: src/locale.cpp
===================================================================
--- src/locale.cpp
+++ src/locale.cpp
@@ -6031,66 +6031,66 @@
#endif
}
-template class collate<char>;
-template class collate<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS collate<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS collate<wchar_t>;
-template class num_get<char>;
-template class num_get<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS num_get<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS num_get<wchar_t>;
-template struct __num_get<char>;
-template struct __num_get<wchar_t>;
+template struct _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __num_get<char>;
+template struct _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __num_get<wchar_t>;
-template class num_put<char>;
-template class num_put<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS num_put<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS num_put<wchar_t>;
-template struct __num_put<char>;
-template struct __num_put<wchar_t>;
+template struct _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __num_put<char>;
+template struct _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __num_put<wchar_t>;
-template class time_get<char>;
-template class time_get<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_get<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_get<wchar_t>;
-template class time_get_byname<char>;
-template class time_get_byname<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_get_byname<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_get_byname<wchar_t>;
-template class time_put<char>;
-template class time_put<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_put<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_put<wchar_t>;
-template class time_put_byname<char>;
-template class time_put_byname<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_put_byname<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS time_put_byname<wchar_t>;
-template class moneypunct<char, false>;
-template class moneypunct<char, true>;
-template class moneypunct<wchar_t, false>;
-template class moneypunct<wchar_t, true>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct<char, false>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct<char, true>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct<wchar_t, false>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct<wchar_t, true>;
-template class moneypunct_byname<char, false>;
-template class moneypunct_byname<char, true>;
-template class moneypunct_byname<wchar_t, false>;
-template class moneypunct_byname<wchar_t, true>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct_byname<char, false>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct_byname<char, true>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct_byname<wchar_t, false>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS moneypunct_byname<wchar_t, true>;
-template class money_get<char>;
-template class money_get<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS money_get<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS money_get<wchar_t>;
-template class __money_get<char>;
-template class __money_get<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __money_get<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __money_get<wchar_t>;
-template class money_put<char>;
-template class money_put<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS money_put<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS money_put<wchar_t>;
-template class __money_put<char>;
-template class __money_put<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __money_put<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __money_put<wchar_t>;
-template class messages<char>;
-template class messages<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS messages<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS messages<wchar_t>;
-template class messages_byname<char>;
-template class messages_byname<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS messages_byname<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS messages_byname<wchar_t>;
-template class codecvt_byname<char, char, mbstate_t>;
-template class codecvt_byname<wchar_t, char, mbstate_t>;
-template class codecvt_byname<char16_t, char, mbstate_t>;
-template class codecvt_byname<char32_t, char, mbstate_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<char, char, mbstate_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<wchar_t, char, mbstate_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<char16_t, char, mbstate_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS codecvt_byname<char32_t, char, mbstate_t>;
-template class __vector_base_common<true>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS __vector_base_common<true>;
_LIBCPP_END_NAMESPACE_STD
Index: src/ios.cpp
===================================================================
--- src/ios.cpp
+++ src/ios.cpp
@@ -25,19 +25,19 @@
_LIBCPP_BEGIN_NAMESPACE_STD
-template class basic_ios<char>;
-template class basic_ios<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ios<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ios<wchar_t>;
-template class basic_streambuf<char>;
-template class basic_streambuf<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_streambuf<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_streambuf<wchar_t>;
-template class basic_istream<char>;
-template class basic_istream<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istream<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_istream<wchar_t>;
-template class basic_ostream<char>;
-template class basic_ostream<wchar_t>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostream<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_ostream<wchar_t>;
-template class basic_iostream<char>;
+template class _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS basic_iostream<char>;
class _LIBCPP_HIDDEN __iostream_category
: public __do_message
Index: include/__config
===================================================================
--- include/__config
+++ include/__config
@@ -547,15 +547,20 @@
// only really useful for a DLL. _LIBCPP_DLL should be a compiler builtin define ideally...
#if defined(_LIBCPP_DLL) && defined(cxx_EXPORTS)
# define _LIBCPP_DLL_VIS __declspec(dllexport)
+# define _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS
+# define _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS _LIBCPP_DLL_VIS
#elif defined(_LIBCPP_DLL)
# define _LIBCPP_DLL_VIS __declspec(dllimport)
+# define _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS _LIBCPP_DLL_VIS
+# define _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS
#else
# define _LIBCPP_DLL_VIS
+# define _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS
+# define _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS
#endif
#define _LIBCPP_TYPE_VIS _LIBCPP_DLL_VIS
#define _LIBCPP_FUNC_VIS _LIBCPP_DLL_VIS
#define _LIBCPP_EXCEPTION_ABI _LIBCPP_DLL_VIS
-#define _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS _LIBCPP_DLL_VIS
#define _LIBCPP_HIDDEN
#define _LIBCPP_TYPE_VIS_ONLY
#define _LIBCPP_FUNC_VIS_ONLY
@@ -609,6 +614,10 @@
# endif
#endif
+#ifndef _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS
+# define _LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS
+#endif
+
#ifndef _LIBCPP_INLINE_VISIBILITY
#define _LIBCPP_INLINE_VISIBILITY __attribute__ ((__visibility__("hidden"), __always_inline__))
#endif
Index: docs/DesignDocs/VisibilityMacros.rst
===================================================================
--- docs/DesignDocs/VisibilityMacros.rst
+++ docs/DesignDocs/VisibilityMacros.rst
@@ -71,6 +71,26 @@
However since `_LIBCPP_TYPE_VIS_ONLY` is the same as `_LIBCPP_TYPE_VIS` the
visibility is already correct. The macro has an empty definition with GCC.
+ **Windows Behavior**: `extern template` and `dllexport` are fundamentally
+ incompatible *on a template class* on Windows; the former suppresses
+ instantiation, while the latter forces it. Specifying both on the same
+ declaration makes the template class be instantiated, which is not desirable
+ inside headers. This macro therefore expands to `dllimport` outside of libc++
+ but nothing inside of it (rather than expanding to `dllexport`); instead, the
+ explicit instantiations themselves are marked as exported. Note that this
+ applies *only* to extern template *classes*. Extern template *functions* obey
+ regular import/export semantics, and applying `dllexport` directly to the
+ extern template declaration is the correct thing to do for them.
+
+**_LIBCPP_CLASS_TEMPLATE_INSTANTIATION_VIS**
+ Mark the member functions, typeinfo, and vtable of an explicit instantiation
+ of a class template as being exported by the libc++ library. This attribute
+ must be specified on all template class explicit instantiations.
+
+ It is only necessary to mark the explicit instantiation itself (as opposed to
+ the extern template declaration) as exported on Windows, as discussed above.
+ On all other platforms, this macro has an empty definition.
+
**_LIBCPP_EXTERN_TEMPLATE_INLINE_VISIBILITY**
Mark a member function of a class template as hidden and inline except when
building the libc++ library where it marks the symbol as being exported by
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