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Re: On byte compilation
From: |
tpeplt |
Subject: |
Re: On byte compilation |
Date: |
Mon, 18 Sep 2023 15:07:36 -0400 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/28.2 (gnu/linux) |
Petteri Hintsanen <petterih@iki.fi> writes:
> Hello,
>
> I'm converting some old code to use new bindat-type introduced in
> Emacs 28.1. I'd like to keep the legacy forms for backwards
> compatibility with older emacsen. But there is a problem with byte
> compilation.
>
> Toy example:
>
> (defconst foo-bindat-spec
> (eval-when-compile
> (if (fboundp 'bindat-type)
> (bindat-type ;; new form
> (id uint 32))
> '((id u32)))) ;; legacy form
> "Bindat spec for foo.")
>
> What I try to accomplish here is to assign to foo-bindat-spec either the
> result of (bindat-type ...) or list '((id u32)), depending on whether
> bindat-type macro is available or not. However, Emacs' 27.2 byte
> compiler complains:
>
> foo.el:5:14:Warning: reference to free variable ‘uint’
>
Emacs 28.2 reports this, also. Did you mean 28.2 instead of 27.2?
‘uint’ is a symbol rather than a variable, according to the
documentation in the elisp info manual: (elisp)"Bindat Types". So, it
is good that the compiler is warning you. You would get the same
warning if you used:
(id uintr 32) or (id str 32) or (id strz 32) or (id vec 32),...
The identifier ‘uint’ needs to be quoted: (id 'uint 32) or
alternatively, (id (quote uint) 32), if that is clearer to you.
(type-of uint) => error, void variable
(type-of 'uint) => symbol
Also, if you have not read it or haven’t read it recently, here is the
node in the elisp manual for Eval During Compile:
(elisp) Eval During Compile
--