Re: How to cause a compiler warning?

[João Távora]

On Wed, Jan 17, 2024 at 12:25 PM Alan Mackenzie <acm@muc.de> wrote:

> ARG can be any Lisp form at all.  How would you reformulate the doc
> string to make it less vague and curious?

Call it FORM.  Then add in the text you wrote to Richard, who
seem to have also been confused.

I got the idea of it pretty quickly, even with the ARG naming,
so take that as a data point.

> Really?  Can you point out any such existing macro in the source files
> of the byte compiler?  You must be aware that warning messages without
> source code locations are annoying in the extreme.

Not all macros process forms.  Just search for a macro without arguments.

> source code locations are annoying in the extreme.

That's a bit of an extreme statement.

Macros that don't process source code and are used simply to
generate Lisp code don't have anything else to report. So using
byte-compiler-warn is fine and you'll see the macro invocation
itself highlighted.

> byte-compile-warn-x is intended for use in the byte compiler.  Anybody
> doing work there should be sophisticated enough to understand what to
> do.  In macros which extend the Lisp language, there is
> macroexp-warn-and-return, for anybody who can understand it.  Do people
> actually write such language extensions and expect them to work on old
> Emacs versions?  There may be, but I'm not aware of any.

I write macros that are supposed to work back to Emacs 26 yes.  I
frequently don't bother with byte-compiler-errors as I tend to
let the other macros and special forms my macro expands to do that.
But not necessarily always.

My point is you shouldn't make this a hard rule with such dogmatism
But it was fine to suggest byte-compile-warn-x, which I didn't
know about, so thanks.