Initial take on build2-based build

Only C++11 is supported with GCC 4.8 and up and VC 14 and up.

This change also introduces the ODB_THREADS_CXX11 threading model. It
is the default for the build2 build but can be disabled with a global
ODB_THREADS_NONE define (global means that it should be in effect both
when building and using the library).

1 files changed, 39 insertions, 0 deletions

diff --git a/odb/details/export.hxx b/odb/details/export.hxx
index 8b36cae..51d6849 100644
--- a/odb/details/export.hxx
+++ b/odb/details/export.hxx
@@ -9,6 +9,43 @@
 
 #include <odb/details/config.hxx>
 
+// Normally we don't export class templates (but do complete specializations),
+// inline functions, and classes with only inline member functions. Exporting
+// classes that inherit from non-exported/imported bases (e.g., std::string)
+// will end up badly. The only known workarounds are to not inherit or to not
+// export. Also, MinGW GCC doesn't like seeing non-exported function being
+// used before their inline definition. The workaround is to reorder code. In
+// the end it's all trial and error.
+
+#ifdef LIBODB_BUILD2
+
+#if defined(LIBODB_STATIC)         // Using static.
+#  define LIBODB_EXPORT
+#elif defined(LIBODB_STATIC_BUILD) // Building static.
+#  define LIBODB_EXPORT
+#elif defined(LIBODB_SHARED)       // Using shared.
+#  ifdef _WIN32
+#    define LIBODB_EXPORT __declspec(dllimport)
+#  else
+#    define LIBODB_EXPORT
+#  endif
+#elif defined(LIBODB_SHARED_BUILD) // Building shared.
+#  ifdef _WIN32
+#    define LIBODB_EXPORT __declspec(dllexport)
+#  else
+#    define LIBODB_EXPORT
+#  endif
+#else
+// If none of the above macros are defined, then we assume we are being used
+// by some third-party build system that cannot/doesn't signal the library
+// type. Note that this fallback works for both static and shared but in case
+// of shared will be sub-optimal compared to having dllimport.
+//
+#  define LIBODB_EXPORT            // Using static or shared.
+#endif
+
+#else // LIBODB_BUILD2
+
 #ifdef LIBODB_STATIC_LIB
 #  define LIBODB_EXPORT
 #else
@@ -35,6 +72,8 @@
 #  endif
 #endif
 
+#endif // LIBODB_BUILD2
+
 #include <odb/post.hxx>
 
 #endif // ODB_DETAILS_EXPORT_HXX