Clarify use of struct stat on Windows

glib/gstdio.h

@@ -89,12 +89,49 @@ int g_mkdir     (const gchar *filename,
 
 int g_chdir     (const gchar *path);
 
+#ifdef G_OS_WIN32
+
+/* The _g_stat_struct struct tag is an internal implementation detail
+ * and not part of the public GLib API.
+ */
+
+#if defined (_MSC_VER) && !defined(_WIN64)
+
+/* Make it clear that we mean the struct with 32-bit st_size and
+ * 32-bit st_*time fields as that is how the 32-bit GLib DLL normally
+ * has been compiled. If you get a compiler warning when calling
+ * g_stat(), do take it seriously and make sure that the type of
+ * struct stat the code in GLib fills in matches the struct the type
+ * of struct stat you pass to g_stat(). To avoid hassle, just use the
+ * GIO API instead which doesn't use struct stat to get file
+ * attributes, .
+ */
+#define _g_stat_struct _stat32
+
+#else
+
+#define _g_stat_struct _stat
+
+#endif
+
+int g_stat      (const gchar           *filename,
+                 struct _g_stat_struct *buf);
+
+int g_lstat     (const gchar           *filename,
+                 struct _g_stat_struct *buf);
+
+#else
+
+/* No _g_stat_struct used on Unix */
+
 int g_stat      (const gchar *filename,
                  struct stat *buf);
 
 int g_lstat     (const gchar *filename,
                  struct stat *buf);
 
+#endif
+
 int g_unlink    (const gchar *filename);
 
 int g_remove    (const gchar *filename);