I think that by far the most frustrating thing about the new “Missing `lexical-binding’ cookie” warning is that it’s all implemented in a way which railroads hapless users into adding it with the value `t’ in situations when they should be setting it to `nil’.
Adding the cookie as “-*- lexical-binding: t; -*-” is for elisp programmers who understand the difference and are prepared to implement the conversion and fix the bugs.
Users who either don’t understand (in a lot of detail) what it all means, or who simply want to make the warning go away with the minimum of effort, need to set “-*- lexical-binding: nil; -*-”. And yet when this question comes up, I almost never see anyone pointing out that “nil” is the correct value to safely maintain the status quo.
– Anonymous 2025-12-15 07:23 UTC
Very good points, thanks!
– mbork 2025-12-22 19:35 UTC