switch to gcc-4.5 and symlinks for default versions

[Marcin Juszkiewicz]

Now gcc-4.[45]-armel-cross uses update-alternatives to handle which is default. This needs to be changed to follow normal gcc.

Implementation plan:

1. create gcc-defaults-armel-cross which will switch to gcc-4.5: DONE
2. create gcc-defaults-armel-cross which will use symlinks: DONE
3. drop postinst/prerm of gcc-4.[3456]-armel-cross to not use u-a: DONE
4. add preinst of gcc-4.[3456]-armel-cross to remove old u-a: DONE
5. upload newer gcc-4.[45]-armel-cross into archive to get rid of u-a: DONE
6. add conflicts on gcc-4.[45]-armel-cross (versions with u-a) to gcc-defaults-armel-cross packages: DONE
7. upload gcc-defaults-armel-cross into archive: TODO

[Marcin Juszkiewicz (hrw)]

This should be done in the preinst instead. Rationale: update-alternatives is part of dpkg, so doesn't require any Pre-Depends; and a dependency (such as the gcc-arm-linux-gnueabi dependency on gcc-4.5-arm-linux-gnueabi) does not prevent one package from being unpacked before the postinst of another package it depends on has been run. So if you do this in the postinst, you get:

 - gcc-4.5-arm-linux-gnueabi unpacked (enforced by the Conflicts: from gcc-arm-linux-gnueabi)
 - gcc-arm-linux-gnueabi unpacked; overwrites /usr/bin/arm-linux-gnueabi-gcc symlink
 - gcc-4.5-arm-linux-gnueabi configured; u-a remove runs, removing the symlink
 - gcc-arm-linux-gnueabi configured - but the gcc symlink is now missing

Otherwise, this looks ok.

[Matthias Klose (doko)]

please make sure that the maintainer scripts are only modified for the cross-builds, not the native builds

[Marcin Juszkiewicz (hrw)]

This patch removes all postinstall and prerm scripts used to set alternatives for cross toolchain packages. Additionally it adds preinst scripts which use update-alternatives to remove previously set alternatives for cross compiler.

Native build does not used postinst/prerm scripts at all and is not affected. Change will need to be done in gcc-4.[3-6] source packages as they are present in Debian 'sid'. gcc-4.1 is present in squeeze, gcc-4.2 only in lenny and I do not know should they be affected too or not.

[Marcin Juszkiewicz (hrw)]

gcc-4.4 got released with fixes

[Launchpad Janitor (janitor)]

This bug was fixed in the package gcc-4.5-armel-cross - 1.47

---------------
gcc-4.5-armel-cross (1.47) natty; urgency=low

  * "Say good bye to update-alternatives" release - LP: #676454
    - components does not register into u-a anymore - selection of default
      version is now done by gcc-defaults-armel-cross package.
    - bumped gcc-4.5-source to 4.5.2-8~
 -- Marcin Juszkiewicz <email address hidden> Mon, 04 Apr 2011 17:08:46 +0200

[Launchpad Janitor (janitor)]

This bug was fixed in the package gcc-4.4-armel-cross - 1.39

---------------
gcc-4.4-armel-cross (1.39) natty; urgency=low

  * "Say good bye to update-alternatives" release - LP: #676454
    - components does not register into u-a anymore - selection of default
      version is now done by gcc-defaults-armel-cross package.
    - bumped requirements to 4.4.5-15 which introduced needed changes
  * fixed path to quilt patches (not present now)
  * provide only required packages without libraries which are provided from
    gcc 4.5/4.6 packages
  * use PKG_IGNORE_CURRENTLY_BUILDING instead of NO_PKG_MANGLE to get -dbgsym
    packages - LP: #711523
  * drop old, not used code to regenerate debian/control
  * change dependencies to Debian ones
 -- Marcin Juszkiewicz <email address hidden> Fri, 01 Apr 2011 12:02:56 +0200

[Launchpad Janitor (janitor)]

This bug was fixed in the package gcc-defaults-armel-cross - 1.5

---------------
gcc-defaults-armel-cross (1.5) natty; urgency=low

  * "Say good bye to update-alternatives" release - LP: #676454
    - components does not register into u-a anymore - selection of default
      version is now done by gcc-defaults-armel-cross package.
 -- Marcin Juszkiewicz <email address hidden> Fri, 15 Apr 2011 16:01:49 +0300