[gentoo-user] Downgrading gcc

[gentoo-user] Downgrading gcc

[meino.cramer]

Hi,

I want to downgrade gcc from 4.5.3-r1 to 4.4.5.

The Gentoo gcc UPgrade guide tells me, that ABI are only upward
compatible which implies problems when downgrading and not upgrading.

Nonetheless a downgrade is needed here and I want to go 
to gcc-4.4.5.

How can I acchieve this in a clean way?

Best regards,
mcc

[gentoo-user] Re: Downgrading gcc

[Nikos Chantziaras]

On 20/02/12 06:20, meino.cramer@gmx.de wrote:
> Hi,
>
> I want to downgrade gcc from 4.5.3-r1 to 4.4.5.
>
> The Gentoo gcc UPgrade guide tells me, that ABI are only upward
> compatible which implies problems when downgrading and not upgrading.
>
> Nonetheless a downgrade is needed here and I want to go
> to gcc-4.4.5.
>
> How can I acchieve this in a clean way?

You don't need to downgrade.  You can just emerge it alongside 4.5.3 and 
switch to it with "gcc-config".  You can switch back and forth at will, 
meaning that you can build specific packages with 4.4.5 and keep the 
rest of the packages on 4.5.3.

Or if you really want everything built with 4.4.5, you can switch to it 
with "gcc-config" and then "emerge -e world".

Re: [gentoo-user] Downgrading gcc

[Pandu Poluan]

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Just re-emerge the older version e.g. emerge =...gcc-4.4.5 (... is the
category). Then use eselect gcc or gcc-config to select the active gcc
version.

CMIIW

Rgds,
 On Feb 20, 2012 11:24 AM, <meino.cramer@gmx.de> wrote:

> Hi,
>
> I want to downgrade gcc from 4.5.3-r1 to 4.4.5.
>
> The Gentoo gcc UPgrade guide tells me, that ABI are only upward
> compatible which implies problems when downgrading and not upgrading.
>
> Nonetheless a downgrade is needed here and I want to go
> to gcc-4.4.5.
>
> How can I acchieve this in a clean way?
>
> Best regards,
> mcc
>
>
>
>
>
>
>
>

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[gentoo-user] Re: Downgrading gcc

[Nikos Chantziaras]

On 20/02/12 06:38, Pandu Poluan wrote:
> Just re-emerge the older version e.g. emerge =...gcc-4.4.5 (... is the
> category). Then use eselect gcc or gcc-config to select the active gcc
> version.

It's better to emerge it by using its slot:

   emerge gcc:4.4

so you can get updates normally for that slot.



>
> CMIIW
>
> Rgds,
>
> On Feb 20, 2012 11:24 AM, <meino.cramer@gmx.de
> <mailto:meino.cramer@gmx.de>> wrote:
>
>     Hi,
>
>     I want to downgrade gcc from 4.5.3-r1 to 4.4.5.
>
>     The Gentoo gcc UPgrade guide tells me, that ABI are only upward
>     compatible which implies problems when downgrading and not upgrading.
>
>     Nonetheless a downgrade is needed here and I want to go
>     to gcc-4.4.5.
>
>     How can I acchieve this in a clean way?
>
>     Best regards,
>     mcc
>
>
>
>
>
>
>

[gentoo-user] Re: Downgrading gcc

[walt]

On 02/19/2012 08:20 PM, meino.cramer@gmx.de wrote:
> Hi,
> 
> I want to downgrade gcc from 4.5.3-r1 to 4.4.5.
> 
> The Gentoo gcc UPgrade guide tells me, that ABI are only upward
> compatible which implies problems when downgrading and not upgrading.
> 
> Nonetheless a downgrade is needed here and I want to go 
> to gcc-4.4.5.
> 

As the others have already said, gcc-config is the way to switch between
gcc versions.  In theory, every time you switch between different gcc's
you *should* run 'fix_libtool_files.sh <old-gcc-version-number>' *and*
recompile every package that links to libstdc++ (because libstdc++ is
part of the gcc package and gcc-config switches versions of libstdc++).

I suspect most people don't actually do those things, however :)
Just keep it in mind if any c++ applications start acting weird.