fix compilation for Python3.12

src/ctypes.pxd

@@ -62,7 +62,7 @@ cdef extern from 'taglib/tfile.h' namespace 'TagLib':
 
 cdef extern from 'taglib/fileref.h' namespace 'TagLib::FileRef':
     IF UNAME_SYSNAME == "Windows":
-        cdef File* create(const Py_UNICODE*) except +
+        cdef File* create(const wchar_t*) except +
     ELSE:
         cdef File* create(const char*) except +
 

src/taglib.pyx

@@ -39,6 +39,14 @@ cdef dict propertyMapToDict(ctypes.PropertyMap map):
             dct[tag].append(toStr(value))
     return dct
 
+cdef ctypes.File* create_wrapper(unicode path):
+    IF UNAME_SYSNAME == "Windows":
+        cdef wchar_t *wchar_path = PyUnicode_AsWideCharString(path, NULL)
+        cdef ctypes.File* file = ctypes.create(wchar_path)
+        PyMem_Free(wchar_path)
+        return file
+    ELSE:
+        return ctypes.create(path)
 
 cdef class File:
     """Class representing an audio file with metadata ("tags").
@@ -80,12 +88,7 @@ cdef class File:
                 path = path.decode('utf8')
             path = Path(path)
         self.path = path
-        IF UNAME_SYSNAME == "Windows":
-            # create on windows takes wchar_t* which Cython automatically converts to
-            # from unicode strings
-            self.cFile = ctypes.create(str(self.path))
-        ELSE:
-            self.cFile = ctypes.create(str(self.path).encode('utf8'))
+        self.cFile = create_wrapper(str(self.path))
         if not self.cFile or not self.cFile.isValid():
             raise OSError(f'Could not read file {path}')