bug#33828: 26.1; Unbound defvar across compilation units

["João Távora" <joaotavora@gmail.com>]

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On Sat, Dec 22, 2018 at 10:41 PM Philipp Stephani <p.stephani2@gmail.com>
wrote:

> Am Sa., 22. Dez. 2018 um 03:46 Uhr schrieb João Távora <
> joaotavora@gmail.com>:
> >
> > Eli Zaretskii <eliz@gnu.org> writes:
> >
> > >> From: Luís Oliveira <luismbo@gmail.com>
> > >> Date: Fri, 21 Dec 2018 12:02:55 +0000
> > >> Cc: João Távora <joaotavora@gmail.com>
> > >>
> > >> I think I've come across a bug.
> > >
> > > Doesn't look like a bug to me.
> >
> > Indeed, it's the behaviour described in the Emacs manual, but the
> > motivation is questionable: it says it's useful for shooshing the
> > byte-compiler's warnings.  Aren't there better alternatives to do this
> > instead of imposing this seeming inconsistency?
>
> The better alternative is to explicitly `require' the library that
> defines the variable.
> I see the one-argument `defvar' as the variable equivalent to
> `declare-function' - it announces that a variable exists without
> defining it. (Maybe there should be a `declare-variable' macro to
> mirror `declare-function'.) As such, its use should be exceptional;
> most libraries should make sure to not have cyclic dependencies and
> use plain `require'.
>

I think in Luís original report there is a `require' of the library where
the variable is declared before using it. Unfortunately it only works
when it is declared with an initial value.

João

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