Re: Emacs 26.0.50 (address@hidden) Nested defsubst fails

[Stefan Monnier]

> According to that file, defsubst and cl-defsubst appear to have
> different issues with each --- though defsubst at least fo rmy use-case
> has worked well for 20+ years.

`defsubst` is supposed to work reliably (with the caveat that it
doesn't support recursion, which would result in infinite-inlining) and
be very easy to use.

`cl-defsubst` can result in slightly more efficient code, but has
various quirks.

`define-inline` is designed to be reliable and give good performance: it
should result in code that's at least as efficient as that of
`cl-defubst`.  But it requires more effort on the part of the programmer
(it asks the programmer to write a kind of restricted macro).

I think `cl-defsubst` should be deprecated: if performance really
matters, `define-inline` is a better choice anyway and it's not that
hard to use.

Maybe the same could be said of `defsubst` but I haven't thought enough
about it to be sure.


        Stefan