[SV 63219] Support an "unload" function for loaded objects

If a loaded object defines a symbol <object>_gmk_unload, assume it's
a function and invoke it whenever the loaded object is unloaded.
Original implementation by Dmitry Goncharov <dgoncharov@users.sf.net>

* NEWS: Announce the change.
* doc/make.texi: Describe the behavior.
* src/gnumake.h: Add information to the comments.
* src/makeint.h (unload_all): Declare a new function.
* src/main.c (die): Invoke unload_all().
* src/load.c (unload_func_t): Declare a new type for unload.
(struct load_list): Remember the unload symbol if it exists.
(load_object): Move the parsing of the object name from load_file.
Check for the _gmk_unload symbol and if found, remember it.
(load_file): Allow load_object to do object filename parsing.
(unload_file): Remove the load_list entry when unloading the object.
(unload_all): Unload all the loaded objects.
* tests/scripts/features/loadapi: Test the unload function.

1 files changed, 10 insertions, 1 deletions

diff --git a/src/gnumake.h b/src/gnumake.h
index 3ebe6621..b448a3c1 100644
--- a/src/gnumake.h
+++ b/src/gnumake.h
@@ -35,7 +35,16 @@ typedef char *(*gmk_func_ptr)(const char *nm, unsigned int argc, char **argv);
 
      int <setup_fn> (unsigned int abi_version, const gmk_floc *flocp);
 
-   The abi_version will be set to GMK_ABI_VERSION.  */
+   The abi_version will be set to GMK_ABI_VERSION.
+
+   When an object is unloaded by GNU Make, an unload method will be invoked.
+   The name of the method is derived from the filename of the object, with
+   _gmk_unload appended.  It has the signature:
+
+     void <object>_gmk_unload (void);
+
+  There will only be one unload method invoked regardless of the number of
+  setup methods within the object.  */
 
 #ifdef _WIN32
 # ifdef GMK_BUILDING_MAKE