[gentoo-user] Re: A Glitch in the Matrix or just another burb of emerge... ;)

[Jonathan Callen]

On 05/16/2016 12:34 PM, Meino.Cramer@×××.de wrote:
> Jonathan Callen <jcallen@g.o> [16-05-16 14:09]:
>> On 05/13/2016 06:09 PM, Grant Edwards wrote:
>>> On 2016-05-11, Jonathan Callen <jcallen@g.o> wrote:
>>>
>>>> Looking further at the ebuilds in question, it appears that if you wish
>>>> to have older versions of GCC installed with >=gcc-4.9, you need to have
>>>> USE=multislot on the *newer* versions of gcc (this USE=multislot doesn't
>>>> appear to be completely broken like the old USE=multislot was; now the
>>>> SLOTs are constant with respect to USE).
>>>
>>> So slots no longer "just work" like they have for the past 15 years?
>>>
>>> You now have to explicitly request installation in a slot by setting
>>> the multislot flag?
>>>
>>> Did I miss an eselect news warning about this?
>>>
>>> Is this true for all packages that were previously installed in slots,
>>> or have gcc and a select few been chosen specially for this breakage?
>>>
>>
>> In this case, it's *just* GCC that has this issue.  It appears that the
>> definition of the "multislot" flag for sys-devel/gcc,
>> sys-devel/gcc-apple, and sys-devel/kgcc64 changed from meaning "Make all
>> the SLOTs include the minor version" (so SLOT=4.9.3) to "Allow multiple
>> versions of GCC to be installed at all (instead of one per CTARGET)"
>> [although it doesn't quite do that yet; reason unknown].  This change
>> appears to have been committed back in March, the reason we are all
>> seeing it hit now (as of 8 May) is that portage finally has a reason to
>> want to recompile GCC, because there is a new "vtv" flag available (for
>> vtable verification).
>>
>> --
>> Jonathan Callen
>>
>
>
> Hi,
>
> me again, the problem owner...
>
> I read elsewhere, that the ANDROID-IDE and crosscompiling
> for Atmel-chips has a problem with newer versions of gcc
> than those being installed on my system before the glitch
> in the Matrix happened.
>
> I cannot decipher the message of thread exactly enough
> to decide whether that glitch is a problem of emerge/portage
> and need to be fixed there (and I have to wait until then) or
> whether I am able to fix it (I dont like workarounds for
> tools, which decide over the go/no go of a system which
> is based on gcc that much as Gentoo does, though).
>
> And...if I have to fix something:
> What exactly should I do?
>
> Thanks for any help for a non-Neo in advance!
> Best regards,
> Meino
>

The simplest solution to get multiple versions of GCC installed at the
same time is to add "sys-devel/gcc multislot" to your
/etc/portage/package.use (if using crossdev (and you know if you are),
you also would want "cross-CTARGET/gcc multislot", where CTARGET is the
target of your crossdev install).

This will remove all of the blockers on older versions of GCC, at the
expense of having to recompile some/all of them.  The only thing that
the multislot flags controls at this point is the blockers; not having
USE=multislot prevents old versions from remaining installed (i.e.,
setting the flag *allows* old versions to remain installed).

-- 
Jonathan Callen