Fix interfacing with and remaking dynamic objects on MS-Windows.

 load.c (load_object, load_file): Accept an additional argument
 DLP and return in it a pointer that can be used to unload the
 dynamic object.
 read.c (eval): Call load_file with an additional argument, and
 record the pointer returned there in the 'struct file' object of
 dynamic objects in that object's 'struct file'.
 commands.c (execute_file_commands): Unload dynamic objects
 before remaking them, to avoid failure to remake if the OS doesn't
 allow overwriting objects that are in use.
 filedef.h (struct file): New member dlopen_ptr.
 gnumake.h (GMK_EXPORT): Define to dllexport/dllimport
 decorations for Windows and to nothing on other platforms.
 (gmk_eval, gmk_expand, gmk_add_function): Add GMK_EXPORT qualifier
 to prototypes.
 makeint.h (MAIN): Define before including gnumake.h, to give
 correct dllexport decorations to exported functions.
 (load_file): Adjust prototype.
 loadapi.c: Don't include gnumake.h, since makeint.h already
 includes it, and takes care of defining MAIN before doing so.
 build_w32.bat (LinkGCC): Produce an import library for functions
 exported by Make for loadable dynamic objects.

 w32/compat/posixfcn.c (dlclose): New function.
 w32/include/dlfcn.h (dlclose): Add prototype.

 scripts/features/load: Fix signatures of testload_gmk_setup and
 explicit_setup, to bring them in line with the documentation.

1 files changed, 16 insertions, 5 deletions

diff --git a/gnumake.h b/gnumake.h
index c6f7bd8..a6308fe 100644
--- a/gnumake.h
+++ b/gnumake.h
@@ -26,13 +26,23 @@ typedef struct
     unsigned long lineno;
   } gmk_floc;
 
+#ifdef _WIN32
+# ifdef MAIN
+#  define GMK_EXPORT  __declspec(dllexport)
+# else
+#  define GMK_EXPORT  __declspec(dllimport)
+# endif
+#else
+# define GMK_EXPORT
+#endif
+
 
 /* Run $(eval ...) on the provided string BUFFER.  */
-void gmk_eval (const char *buffer, const gmk_floc *floc);
+void GMK_EXPORT gmk_eval (const char *buffer, const gmk_floc *floc);
 
 /* Run GNU make expansion on the provided string STR.
    Returns an allocated buffer that the caller must free.  */
-char *gmk_expand (const char *str);
+char * GMK_EXPORT gmk_expand (const char *str);
 
 /* Register a new GNU make function NAME (maximum of 255 chars long).
    When the function is expanded in the makefile, FUNC will be invoked with
@@ -49,8 +59,9 @@ char *gmk_expand (const char *str);
    If EXPAND_ARGS is 0, the arguments to the function will not be expanded
    before FUNC is called.  If EXPAND_ARGS is non-0, they will be expanded.
 */
-void gmk_add_function (const char *name,
-                       char *(*func)(const char *nm, int argc, char **argv),
-                       int min_args, int max_args, int expand_args);
+void GMK_EXPORT gmk_add_function (const char *name,
+				  char *(*func)(const char *nm,
+						int argc, char **argv),
+				  int min_args, int max_args, int expand_args);
 
 #endif  /* _GNUMAKE_H_ */