F36 Change: GHC compiler parallel version installs (Self-Contained Change proposal)

[Ben Cotton]

https://fedoraproject.org/wiki/Changes/GHC_parallel_version_installs


== Summary ==
Introduce ghcX.Y packages to Fedora which can be parallel installed,
in addition to the main ghc package.

== Owner ==
* Name: [[User:Petersen|Jens Petersen]]
* Email: petersen(a)redhat.com


== Detailed Description ==
Currently ghc modules are available in Fedora but they cannot be
installed in parallel.
This Change will enable being able to easily install multiple versions
of ghc in parallel,
which can be useful for development - both for working on different projects
and testing projects for compatibility across different ghc versions.

== Feedback ==
This was proposed to the Fedora Haskell mailing list already and so
far there were no objections.

== Benefit to Fedora ==
Parallel installs of ghc versions will allow more flexible Haskell
development using Fedora Linux.

== Scope ==
* Proposal owners:
** update ghc-rpm-macros to support the packaging [done]
** add ghc9.2 [built for rawhide]
** add ghc9.0 [repo created]
** add ghc8.10 [may not be needed for F36]
** add ghc8.8 [stretch goal]
** add cabal-install3.4 and/or cabal-install3.6 [stretch goal]
** also backport ghcX.Y's to F35, F34, and EPEL

* Other developers: N/A
* Release engineering: N/A
* Policies and guidelines: N/A (not needed for this Change)
* Trademark approval: N/A (not needed for this Change)
* Alignment with Objectives: N/A

== Upgrade/compatibility impact ==

These are new packages so upgrading from older releases should be fine.
Eventually future Fedora version upgrades will probably need to
obsolete very old ghcX.Y versions.

== How To Test ==
1. dnf install ghc ghc9.2 ghc9.0

== User Experience ==
Installing ghc, ghc9.0, and ghc9.2 will give you /usr/bin/ghc,
/usr/bin/ghc-9.0.x and /usr/bin/ghc-9.2.x.
Their Haskell libraries will have ghc versioned directories and .so files.

== Dependencies ==
N/A


== Contingency Plan ==

* Contingency mechanism: (What to do?  Who will do it?) N/A (not a
System Wide Change)
* Contingency deadline: N/A (not a System Wide Change)
* Blocks release? N/A (not a System Wide Change)


== Documentation ==
N/A (not a System Wide Change)

== Release Notes ==
With the introduction of versioned ghcX.Y packages multiple versions
of the Haskell GHC compiler can now be installed parallel in the
Fedora Linux.


-- 
Ben Cotton
He / Him / His
Fedora Program Manager
Red Hat
TZ=America/Indiana/Indianapolis

[Neal Gompa]

On Mon, Dec 13, 2021 at 2:38 PM Ben Cotton <bcotton(a)redhat.com&gt; wrote:
>  https://fedoraproject.org/wiki/Changes/GHC_parallel_version_installs
>
>
>  == Summary ==
>  Introduce ghcX.Y packages to Fedora which can be parallel installed,
>  in addition to the main ghc package.
>
>  == Owner ==
>  * Name: [[User:Petersen|Jens Petersen]]
>  * Email: petersen(a)redhat.com
>
>
>  == Detailed Description ==
>  Currently ghc modules are available in Fedora but they cannot be
>  installed in parallel.
>  This Change will enable being able to easily install multiple versions
>  of ghc in parallel,
>  which can be useful for development - both for working on different projects
>  and testing projects for compatibility across different ghc versions.
>
>  == Feedback ==
>  This was proposed to the Fedora Haskell mailing list already and so
>  far there were no objections.
>
>  == Benefit to Fedora ==
>  Parallel installs of ghc versions will allow more flexible Haskell
>  development using Fedora Linux.
>
>  == Scope ==
>  * Proposal owners:
>  ** update ghc-rpm-macros to support the packaging [done]
>  ** add ghc9.2 [built for rawhide]
>  ** add ghc9.0 [repo created]
>  ** add ghc8.10 [may not be needed for F36]
>  ** add ghc8.8 [stretch goal]
>  ** add cabal-install3.4 and/or cabal-install3.6 [stretch goal]
>  ** also backport ghcX.Y's to F35, F34, and EPEL
>
>  * Other developers: N/A
>  * Release engineering: N/A
>  * Policies and guidelines: N/A (not needed for this Change)
>  * Trademark approval: N/A (not needed for this Change)
>  * Alignment with Objectives: N/A
>
>  == Upgrade/compatibility impact ==
>
>  These are new packages so upgrading from older releases should be fine.
>  Eventually future Fedora version upgrades will probably need to
>  obsolete very old ghcX.Y versions.
>
>  == How To Test ==
>  1. dnf install ghc ghc9.2 ghc9.0
>
>  == User Experience ==
>  Installing ghc, ghc9.0, and ghc9.2 will give you /usr/bin/ghc,
>  /usr/bin/ghc-9.0.x and /usr/bin/ghc-9.2.x.
>  Their Haskell libraries will have ghc versioned directories and .so files.
>
>  == Dependencies ==
>  N/A
>
>
>  == Contingency Plan ==
>
>  * Contingency mechanism: (What to do?  Who will do it?) N/A (not a
>  System Wide Change)
>  * Contingency deadline: N/A (not a System Wide Change)
>  * Blocks release? N/A (not a System Wide Change)
>
>
>  == Documentation ==
>  N/A (not a System Wide Change)
>
>  == Release Notes ==
>  With the introduction of versioned ghcX.Y packages multiple versions
>  of the Haskell GHC compiler can now be installed parallel in the
>  Fedora Linux.
>  
So will the default version be the "ghc" package going forward? How
will defaults be handled in future Fedora Linux releases?


-- 
真実はいつも一つ！/ Always, there's only one truth!

[Jens-Ulrik Petersen]

On Wed, Dec 22, 2021 at 11:00 PM Neal Gompa <ngompa13(a)gmail.com&gt; wrote:

>  So will the default version be the "ghc" package going
> forward? 

That's correct - general Haskell users/consumers should just continue to
use the main ghc package and ghc-* libraries.

ghcX.Y is for people who need/want to use or test different (newer/older)
ghc versions,
rather like the compatibility llvmX packages.
ghc9.2 is already available in Rawhide and F35 updates testing, and ghc9.0
should be available soon too.


>  How will defaults be handled in future Fedora Linux releases? 

The main Fedora ghc package will continue to be maintained and upgraded
along with the ecosystem.
It is not completely clear yet if the ghc package set will move to ghc-9.0
in time for F36 GA, otherwise hopefully to ghc-8.10.7.
ghcX.Y can also provide a better testing ground for packaging improvements
(than the ghc modules) before they land in the main ghc package.
It will make new minor ghc versions more easily available in Fedora (and
EPEL where ghcX.Y will be even more meaningful).

Jens

[Tom Stellard]

On 12/13/21 08:56, Ben Cotton wrote:
>  https://fedoraproject.org/wiki/Changes/GHC_parallel_version_installs
>  
>  
>  == Summary ==
>  Introduce ghcX.Y packages to Fedora which can be parallel installed,
>  in addition to the main ghc package.
>  
>  == Owner ==
>  * Name: [[User:Petersen|Jens Petersen]]
>  * Email: petersen(a)redhat.com
>  
>  
>  == Detailed Description ==
>  Currently ghc modules are available in Fedora but they cannot be
>  installed in parallel. 
What is the plan for the ghc modules?

-Tom

>  This Change will enable being able to easily install multiple
> versions
>  of ghc in parallel,
>  which can be useful for development - both for working on different projects
>  and testing projects for compatibility across different ghc versions.
>  
>  == Feedback ==
>  This was proposed to the Fedora Haskell mailing list already and so
>  far there were no objections.
>  
>  == Benefit to Fedora ==
>  Parallel installs of ghc versions will allow more flexible Haskell
>  development using Fedora Linux.
>  
>  == Scope ==
>  * Proposal owners:
>  ** update ghc-rpm-macros to support the packaging [done]
>  ** add ghc9.2 [built for rawhide]
>  ** add ghc9.0 [repo created]
>  ** add ghc8.10 [may not be needed for F36]
>  ** add ghc8.8 [stretch goal]
>  ** add cabal-install3.4 and/or cabal-install3.6 [stretch goal]
>  ** also backport ghcX.Y's to F35, F34, and EPEL
>  
>  * Other developers: N/A
>  * Release engineering: N/A
>  * Policies and guidelines: N/A (not needed for this Change)
>  * Trademark approval: N/A (not needed for this Change)
>  * Alignment with Objectives: N/A
>  
>  == Upgrade/compatibility impact ==
>  
>  These are new packages so upgrading from older releases should be fine.
>  Eventually future Fedora version upgrades will probably need to
>  obsolete very old ghcX.Y versions.
>  
>  == How To Test ==
>  1. dnf install ghc ghc9.2 ghc9.0
>  
>  == User Experience ==
>  Installing ghc, ghc9.0, and ghc9.2 will give you /usr/bin/ghc,
>  /usr/bin/ghc-9.0.x and /usr/bin/ghc-9.2.x.
>  Their Haskell libraries will have ghc versioned directories and .so files.
>  
>  == Dependencies ==
>  N/A
>  
>  
>  == Contingency Plan ==
>  
>  * Contingency mechanism: (What to do?  Who will do it?) N/A (not a
>  System Wide Change)
>  * Contingency deadline: N/A (not a System Wide Change)
>  * Blocks release? N/A (not a System Wide Change)
>  
>  
>  == Documentation ==
>  N/A (not a System Wide Change)
>  
>  == Release Notes ==
>  With the introduction of versioned ghcX.Y packages multiple versions
>  of the Haskell GHC compiler can now be installed parallel in the
>  Fedora Linux.
>  
>

[Vitaly Zaitsev]

On 13/12/2021 17:56, Ben Cotton wrote:
>  Introduce ghcX.Y packages to Fedora which can be parallel installed,
>  in addition to the main ghc package. 
What about doing the same for GCC? When the new GCC snapshot is released 
for Rawhide, there are a lot of ICEs.

Currently the package maintainers have only one option if they want to 
fix FTBFS quickly - switching to Clang. I'd like to see the previous 
supported versions of GCC in separate packages: gcc11, gcc10, etc.

It will also help CUDA developers. They are currently forced to use Ubuntu.

-- 
Sincerely,
   Vitaly Zaitsev (vitaly(a)easycoding.org)

[Jens-Ulrik Petersen]

On Fri, Dec 24, 2021 at 11:49 AM Tom Stellard <tstellar(a)redhat.com&gt; wrote:

>  On 12/13/21 08:56, Ben Cotton wrote:
>  > https://fedoraproject.org/wiki/Changes/GHC_parallel_version_installs
>  >
>  > == Summary ==
>  > Introduce ghcX.Y packages to Fedora which can be parallel installed,
>  > in addition to the main ghc package.
>  : 
>  == Detailed Description ==
>  > Currently ghc modules are available in Fedora but they cannot be
>  > installed in parallel.
>
>  What is the plan for the ghc modules? 

It's a good question: I kind of avoided going into detail on this point in
the Change,
since I was not intending to remove/drop the modules just yet.
In the meantime I have added an optional ghcX.Y-compiler-default subpackage
which allows making ghcX.Y the default ghc too though, so with that
the modules no longer seem to provide any advantage.
If there are no strong objections I think I will probably drop the modules
before F37 anyway.
But I didn't really want to frame this Change as "demodularization", but I
will concede that
maintaining the modules has been more stressful than I would like to admit.
Most likely I will also switch EPEL to using ghcX.Y instead of modules.

Jens