Add DLL export/import support

1 files changed, 41 insertions, 0 deletions

diff --git a/bpkg/export b/bpkg/export
new file mode 100644
index 0000000..7bbb994
--- /dev/null
+++ b/bpkg/export
@@ -0,0 +1,41 @@
+// file      : bpkg/export -*- C++ -*-
+// copyright : Copyright (c) 2014-2016 Code Synthesis Ltd
+// license   : MIT; see accompanying LICENSE file
+
+#ifndef BPKG_EXPORT
+#define BPKG_EXPORT
+
+// 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/import 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.
+
+#if defined(LIBBPKG_STATIC)         // Using static.
+#  define LIBBPKG_EXPORT
+#elif defined(LIBBPKG_STATIC_BUILD) // Building static.
+#  define LIBBPKG_EXPORT
+#elif defined(LIBBPKG_SHARED)       // Using shared.
+#  ifdef _WIN32
+#    define LIBBPKG_EXPORT __declspec(dllimport)
+#  else
+#    define LIBBPKG_EXPORT
+#  endif
+#elif defined(LIBBPKG_SHARED_BUILD) // Building shared.
+#  ifdef _WIN32
+#    define LIBBPKG_EXPORT __declspec(dllexport)
+#  else
+#    define LIBBPKG_EXPORT
+#  endif
+#else
+// If none of the above macros are defined, then we assume we are being using
+// 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 LIBBPKG_EXPORT            // Using static or shared.
+#endif
+
+#endif // BPKG_EXPORT