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Re: [Emacs-diffs] master 74f54af: Use eassume (false) for branch that's

From: Eli Zaretskii
Subject: Re: [Emacs-diffs] master 74f54af: Use eassume (false) for branch that's never taken.
Date: Fri, 19 Apr 2019 13:08:49 +0300

> From: Philipp Stephani <address@hidden>
> Date: Fri, 19 Apr 2019 11:52:13 +0200
> Cc: Philipp Stephani <address@hidden>, Emacs developers <address@hidden>
> Am Fr., 19. Apr. 2019 um 10:43 Uhr schrieb Eli Zaretskii <address@hidden>:
> >
> > Philipp, I don't understand this change.  The function in question
> > should return a Lisp_Object, and AFAIU eassume doesn't do that when
> > ENABLE_CHECKING is not defined.  What am I missing?
> >
> The default branch can never be taken. We use eassume(false) in many
> other places to document this.

AFAICT, all those places don't need to return anything, which is
unlike here.

When ENABLE_CHECKING is not defined, which happens in every production
build, eassume expands to code that has no side effects, so the
function will return a random value to its caller.  I don't think this
is desired.  If you want to make sure this branch is never taken even
in a production build, simply call emacs_abort there.

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