Windows: Fix building and running on Python 3.8+

Python 3.8.x and later changed the way how dependent DLLs can be found for a
given Python module that depends on the presence of external, non-system DLLs,
for more fine-grained DLLs searching and loading, as well as for security
purposes, which required the use of os.add_dll_directory().

Thus, the scripts in scanner/ must be updated such that:

-We are able to find and load the GObject and GLib DLLs, at least, on
 initialization, via the use of 'pkg-config --variable bindir', as we already
 depend on the GLib DLLs.   Note that since the gobject-2.0.pc file does not
 have a 'bindir' entry, we use gio-2.0.pc instead to discover the bindir of the
 GObject and GLib DLLs.  Likewise, we use the same technique for pkg-config
 files that are dependent upon when using g-ir-scanner (or friends) on items
 that are higher up in the stack.

-We are able to find any other DLLs (e.g. non-GNOME DLLs such as ZLib) that
 are dependent but are not found in the path(s) given by 'pkg-config --variable
 bindir' with the envvar GI_EXTRA_BASE_DLL_DIRS, as needed.  Note that
 GI_EXTRA_BASE_DLL_DIRS can be multiple paths, and that the results from
 'pkg-config --variable bindir' takes precendence, in a LIFO manner.

1 files changed, 4 insertions, 0 deletions

diff --git a/giscanner/dumper.py b/giscanner/dumper.py
index 61942faf..0c10a780 100644
--- a/giscanner/dumper.py
+++ b/giscanner/dumper.py
@@ -252,6 +252,9 @@ class DumpCompiler(object):
             for ldflag in shlex.split(os.environ.get('LDFLAGS', '')):
                 args.append(ldflag)
 
+        dll_dirs = utils.dll_dirs()
+        dll_dirs.add_dll_dirs(self._packages)
+
         if not self._options.quiet:
             print("g-ir-scanner: link: %s" % (
                 subprocess.list2cmdline(args), ))
@@ -278,6 +281,7 @@ class DumpCompiler(object):
         finally:
             if msys:
                 os.remove(tf_name)
+            dll_dirs.cleanup_dll_dirs()
 
 
 def compile_introspection_binary(options, get_type_functions,