&gt; Maybe we could add code that saves just the (match-beginning 0) and<br>&gt; signals an error if it was not properly preserved.  This would still<br>&gt; require change-functions to save the match-data if they use it, but it<br>
&gt; might catch the offenders earlier.<br><br>I made a crack at it. It was necessary to use save-match-data in a couple of around advices and disable undo-tree to get some basic commands to work. I imagine there would be more cases to resolve.<br>
<br>Are the changes in the .diff what you had in mind roughly?<br><br>