Re: [gentoo-user] Re: Is --changed-deps going to be *that* useless?

[Rich Freeman]

On Tue, Feb 27, 2018 at 1:59 PM, Ian Zimmerman <itz@××××××××××××.org> wrote:
> On 2018-02-27 12:45, Rich Freeman wrote:
>
>> I use --with-bdeps=n because I really don't care that much about
>> build-time deps, other than stuff that is going to get updated anyway
>> like gcc.  These packages don't even need to be installed for software
>> to work correctly, and if a dev does miss an RDEPEND there is a decent
>> chance they'll miss it in DEPEND also.
>
> Ok, so this looks like the relevant one in the current mess, at least.
> But: if you omit --with-bdeps, what happens in the (relatively frequent)
> situation when an already installed package is being updated and
> acquired a new build dependency, which is not yet installed?
>

Portage will automatically install the new build dependency first.
Anytime you explicitly install a package portage checks all
dependencies and ensures they are met.  If either a build-time or
run-time dependency has changed and is no longer satisfied then
portage will take care of that before installing the package.

If a build-time dependency changes then by default portage will ignore
this unless the package actually needs to be reinstalled.

In theory you should never need --with-bdeps=y to actually keep
software running.  If things break without that option it is likely
due to missing dependencies somewhere.

That isn't to say that there aren't potential benefits to using
--with-bdeps=y and --changed-deps.  A package might not NEED its build
system updated to run, but if that build system provides some kind of
improved optimizations then updating the build system and rebuilding
the package could provide runtime benefits.  It just shouldn't be
needed to actually make the package run.  In practice significant
optimization improvements aren't that common from regular version
upgrades/etc.

-- 
Rich