See attached patch.
This is following the recommendations here:
https://support.microsoft.com/en-us/kb/168958
While the existing foo_EXPORT provided by GenerateExportHeader is fine
for use in exporting functions and classes, it isn't apparently
sufficient for template export. This is needed, for example, if you
wish to use templated types in exported classes as members. In this
case you need to use "extern" when importing the exported template, and
this requires a second macro. For example, to export std::string and
std::vector<std::string>:
foo_EXPORT_TEMPLATE template class foo_EXPORT std::allocator<char>;
foo_EXPORT_TEMPLATE template class foo_EXPORT std::basic_string<char,
std::char_traits<char>, std::allocator<char> >;
foo_EXPORT_TEMPLATE template class foo_EXPORT
std::allocator<std::basic_string<char, std::char_traits<char>,
std::allocator<char> > >;
foo_EXPORT_TEMPLATE template class foo_EXPORT
std::vector<std::basic_string<char, std::char_traits<char>,
std::allocator<char> >, std::allocator<std::basic_string<char,
std::char_traits<char>, std::allocator<char> > > >;
With this done, it can then be used in an exported class:
class foo_EXPORT foo
{
std::vector<std::string> val;
public:
foo();
std::vector<std::string> const&
getval() const;
};
Note that I'm by no means a Windows C++ or DLL expert--I'm primarily a
C++ UNIX developer--this is just from reading the docs and experimenting.
An example project making use of this is here:
https://github.com/rleigh-dundee/dlltest
(with unpatched cmake--I create the macros after using the generated
export header)
Regards,
Roger
From 19b63c2b3f89c44ccfe5f0b7e7ef8aa2ea6377a1 Mon Sep 17 00:00:00 2001
From: Roger Leigh <[email protected]>
Date: Thu, 30 Jul 2015 15:47:38 +0100
Subject: [PATCH] GenerateExportHeader: Add EXPORT_TEMPLATE macro
In addition to the foo_EXPORT macro, a foo_EXPORT_TEMPLATE
macro is also generated. This is to allow for explicit
export of templates in Windows DLLs following Microsoft's
guidance here: https://support.microsoft.com/en-us/kb/168958
---
Modules/exportheader.cmake.in | 3 +++
1 file changed, 3 insertions(+)
diff --git a/Modules/exportheader.cmake.in b/Modules/exportheader.cmake.in
index 118de16..f442e98 100644
--- a/Modules/exportheader.cmake.in
+++ b/Modules/exportheader.cmake.in
@@ -4,15 +4,18 @@
#ifdef @STATIC_DEFINE@
# define @EXPORT_MACRO_NAME@
+# define @EXPORT_MACRO_NAME@_TEMPLATE
# define @NO_EXPORT_MACRO_NAME@
#else
# ifndef @EXPORT_MACRO_NAME@
# ifdef @EXPORT_IMPORT_CONDITION@
/* We are building this library */
# define @EXPORT_MACRO_NAME@ @DEFINE_EXPORT@
+# define @EXPORT_MACRO_NAME@_TEMPLATE
# else
/* We are using this library */
# define @EXPORT_MACRO_NAME@ @DEFINE_IMPORT@
+# define @EXPORT_MACRO_NAME@_TEMPLATE extern
# endif
# endif
--
2.5.0
--
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