bug#61730: 30.0.50; Compiler warnings for delq and delete

[Mattias Engdegård]

24 feb. 2023 kl. 21.20 skrev Stefan Monnier <monnier@iro.umontreal.ca>:
> 
>> -    (byte-compile-form arg t))
>> +    ;; Compile args for value (to avoid warnings about unused values),
>> +    ;; emit a discard after each, and trust the LAP peephole optimiser
>> +    ;; to annihilate useless ops.
>> +    (byte-compile-form arg)
>> +    (byte-compile-discard))
> 
> I doubt that it will always result in the same code :-(

Not always indeed, but pretty close. Here is the complete list of .elc files 
that changed size, with their byte-code growth in bytes:

./lisp/emacs-lisp/pcase.elc 1
./lisp/eshell/esh-ext.elc 1
./lisp/emacs-lisp/bytecomp.elc 2
./lisp/mouse.elc 2
./lisp/org/org-agenda.elc 7
./lisp/emacs-lisp/cconv.elc 9

which is as good as zero. Is there a particular construct that you are worried 
about?

Most uses of (ignore ...) are for silencing unused variables, and that case 
should be more or less unchanged with the patch. The same should be true for 
using `ignore` to discard the return values of functions like mapcar or delete 
without warning.