Major upgrade to Boost.Config symbol visibility macros for shared libraries, based on patches from Jürgen Hunold with mods by Beman Dawes. Upgrade Boost.System to use the new visibility macros. Fixes #3697 and provides foundation for fixing 2114, 2309, etc.

[SVN r62140]

include/boost/system/config.hpp

@@ -1,4 +1,4 @@
-//  boost/system/config.hpp  -------------------------------------------------//
+//  boost/system/config.hpp  -----------------------------------------------------------//
 
 //  Copyright Beman Dawes 2003, 2006
 
@@ -18,40 +18,29 @@
 # if defined( BOOST_WINDOWS_API ) && defined( BOOST_POSIX_API )
 #   error both BOOST_WINDOWS_API and BOOST_POSIX_API are defined
 # elif !defined( BOOST_WINDOWS_API ) && !defined( BOOST_POSIX_API )
-#   if defined(_WIN32) || defined(__WIN32__) || defined(WIN32) || defined(__CYGWIN__)
+#   if defined(_WIN32) || defined(__WIN32__) || defined(WIN32)
+      // All Win32 development environments, including 64-bit Windows and MinGW, define 
+      // _WIN32 or one of its variant spellings. Note that Cygwin is a POSIX environment,
+      // so does not define _WIN32 or its variants.
 #     define BOOST_WINDOWS_API
 #   else
 #     define BOOST_POSIX_API 
 #   endif
 # endif
 
-//  enable dynamic linking on Windows  ---------------------------------------//
+//  enable dynamic or static linking as requested --------------------------------------//
 
-//#  if (defined(BOOST_ALL_DYN_LINK) || defined(BOOST_SYSTEM_DYN_LINK)) && defined(__BORLANDC__) && defined(__WIN32__)
-//#    error Dynamic linking Boost.System does not work for Borland; use static linking instead
-//#  endif
-
-#ifdef BOOST_HAS_DECLSPEC // defined in config system
-// we need to import/export our code only if the user has specifically
-// asked for it by defining either BOOST_ALL_DYN_LINK if they want all boost
-// libraries to be dynamically linked, or BOOST_SYSTEM_DYN_LINK
-// if they want just this one to be dynamically liked:
 #if defined(BOOST_ALL_DYN_LINK) || defined(BOOST_SYSTEM_DYN_LINK)
-// export if this is our own source, otherwise import:
-#ifdef BOOST_SYSTEM_SOURCE
-# define BOOST_SYSTEM_DECL __declspec(dllexport)
+# if defined(BOOST_SYSTEM_SOURCE)
+#   define BOOST_SYSTEM_DECL BOOST_SYMBOL_EXPORT
+# else 
+#   define BOOST_SYSTEM_DECL BOOST_SYMBOL_IMPORT
+# endif
 #else
-# define BOOST_SYSTEM_DECL __declspec(dllimport)
-#endif  // BOOST_SYSTEM_SOURCE
-#endif  // DYN_LINK
-#endif  // BOOST_HAS_DECLSPEC
-//
-// if BOOST_SYSTEM_DECL isn't defined yet define it now:
-#ifndef BOOST_SYSTEM_DECL
-#define BOOST_SYSTEM_DECL
+# define BOOST_SYSTEM_DECL
 #endif
 
-//  enable automatic library variant selection  ------------------------------// 
+//  enable automatic library variant selection  ----------------------------------------// 
 
 #if !defined(BOOST_SYSTEM_SOURCE) && !defined(BOOST_ALL_NO_LIB) && !defined(BOOST_SYSTEM_NO_LIB)
 //

include/boost/system/system_error.hpp

@@ -17,9 +17,11 @@ namespace boost
 {
   namespace system
   {
-    //  class system_error  --------------------------------------------------//
+    //  class system_error  ------------------------------------------------------------//
 
-    class system_error : public std::runtime_error
+    class BOOST_SYMBOL_VISIBLE system_error : public std::runtime_error
+    // BOOST_SYMBOL_VISIBLE is needed by GCC to ensure system_error thrown from a shared
+    // library can be caught. See svn.boost.org/trac/boost/ticket/3697 
     {
     public:
       system_error( error_code ec )