[ANNOUNCE] GHC 8.2.1 release candidate 3 available

Hello everyone, I am pleased to at long last announce the third (and almost certainly last) release candidate of GHC 8.2.1. Binary and source distributions can be found at, https://downloads.haskell.org/~ghc/8.2.1-rc3/ This release candidate fixes a number of regressions from 8.0.2 found in -rc2, as well as a major correctness bug (#13615) present in several previous GHC major releases. Users taking advantage of parallelism in their programs will be strongly encouraged to upgrade to 8.2.1 once it is released. Among the other issues resolved in this candidate are, * Functionality allowing GHC to automatically use the ld.gold linker when available (see #13541). Not only has there recently been significant user demand for this feature, but this also serves to work around a performance bug in BFD ld affecting GHC 8.2 (#13739) * A regression resulting in the package cache file to be out-of-date after binary distribution installation (#13375) * Numerous type-checker bugs (#13625, #1370, #13782, #13871, #13594, #13879, #13881, #13875) * A bug wherein a thread blocked on a BLACKHOLE may not be woken up (#13751) * and many more... There are a few changes in release-engineering matters that should be mentioned, * Binary distributions for CentOS 6.7 have been dropped due to the release of CentOS 7.0 which can use Debian 8 binaries. If you would like us to continue to produce CentOS 6.7 bindists please let me know. * GHC HQ now also provides FreeBSD and OpenBSD distributions for amd64; this will allow us to more quickly ship distributions to users by eliminating the need for a long lag time between source release availability and having all binary distributions available. * There is a technology-preview of an AArch64 Linux binary distribution, as well as an ARM Linux build (although the latter won't be uploaded until a few hours from now). AArch64 support is quite preliminary but should be stable in 8.4 thanks to further linker fixes by Moritz Angerman. ARM should be stable. As always, let us know if you encounter problems. If all goes well we will hopefully have a final 8.2.1 release in the next two weeks. Finally, thanks for your patience during this admittedly quite drawn out release cycle. While it has been long, we are confident that the result will be worth the wait. Moreover, we have been steadily working on infrastructure which should shrink future release cycles and give us better testing between releases. More details on this coming soon. Happy testing, - Ben

Hi Ben,
On 7 July 2017 at 13:22, Ben Gamari
I am pleased to at long last announce the third (and almost certainly last) release candidate of GHC 8.2.1. Binary and source distributions can be found at,
Thanks for releasing GHC 8.2.1 RC 3. While testing this RC candidate on Agda we found a compilation error. The error was caused by an *unused* module which *is* compiled by this RC but it *is not* compiled by previous versions of GHC including 8.2.1 RC 2. This module was listed in the `other-modules` field of the `test-suite` section in the .cabal file. After removing the offending module, we didn't find more problems. While I think GHC is doing the right thing here, it is not an obvious error on medium size projects like Agda. This is the reason for sharing this information. Best, -- Andrés La información contenida en este correo electrónico está dirigida únicamente a su destinatario y puede contener información confidencial, material privilegiado o información protegida por derecho de autor. Está prohibida cualquier copia, utilización, indebida retención, modificación, difusión, distribución o reproducción total o parcial. Si usted recibe este mensaje por error, por favor contacte al remitente y elimínelo. La información aquí contenida es responsabilidad exclusiva de su remitente por lo tanto la Universidad EAFIT no se hace responsable de lo que el mensaje contenga. The information contained in this email is addressed to its recipient only and may contain confidential information, privileged material or information protected by copyright. Its prohibited any copy, use, improper retention, modification, dissemination, distribution or total or partial reproduction. If you receive this message by error, please contact the sender and delete it. The information contained herein is the sole responsibility of the sender therefore Universidad EAFIT is not responsible for what the message contains.

On Sunday, July 9, 2017 1:05:44 AM EDT Andrés Sicard-Ramírez wrote:
While testing this RC candidate on Agda we found a compilation error.
The error was caused by an *unused* module which *is* compiled by this RC but it *is not* compiled by previous versions of GHC including 8.2.1 RC 2. This module was listed in the `other-modules` field of the `test-suite` section in the .cabal file. After removing the offending module, we didn't find more problems.
While I think GHC is doing the right thing here, it is not an obvious error on medium size projects like Agda. This is the reason for sharing this information.
Are you saying that Cabal is now compiling an unused module with legitimate errors that GHC detects? If so, that sounds like a Cabal issue rather than a GHC one. As you haven't offered example code, it's a bit hard to see just what you mean.

On 9 July 2017 at 11:50, David Feuer
On Sunday, July 9, 2017 1:05:44 AM EDT Andrés Sicard-Ramírez wrote:
While testing this RC candidate on Agda we found a compilation error.
The error was caused by an *unused* module which *is* compiled by this RC but it *is not* compiled by previous versions of GHC including 8.2.1 RC 2. This module was listed in the `other-modules` field of the `test-suite` section in the .cabal file. After removing the offending module, we didn't find more problems.
While I think GHC is doing the right thing here, it is not an obvious error on medium size projects like Agda. This is the reason for sharing this information.
Are you saying that Cabal is now compiling an unused module with legitimate errors that GHC detects?
No.
From a personal message by Herbert:
On 9 July 2017 at 03:53, Herbert Valerio Riedel
- Prior to Cabal 2.0, the modules listed in `other-modules` were only passed to GHC for library stanzas, but not to executables/benchmarks/test stanzas.
Example: Let's suppose we have the following information in the .cabal file: test-suite foo-test other-modules: M1 , M2 , M3 , Bad where `Bad.hs` a) is not used by `foo-test` and b) generates a compilation error. Due to the above new feature mentioned by Herbert, GHC 8.2.1 RC3/Cabal 2.0 *correctly* report an error in `Bad.hs` but previous versions of GHC/Cabal don't. Best, -- Andrés La información contenida en este correo electrónico está dirigida únicamente a su destinatario y puede contener información confidencial, material privilegiado o información protegida por derecho de autor. Está prohibida cualquier copia, utilización, indebida retención, modificación, difusión, distribución o reproducción total o parcial. Si usted recibe este mensaje por error, por favor contacte al remitente y elimínelo. La información aquí contenida es responsabilidad exclusiva de su remitente por lo tanto la Universidad EAFIT no se hace responsable de lo que el mensaje contenga. The information contained in this email is addressed to its recipient only and may contain confidential information, privileged material or information protected by copyright. Its prohibited any copy, use, improper retention, modification, dissemination, distribution or total or partial reproduction. If you receive this message by error, please contact the sender and delete it. The information contained herein is the sole responsibility of the sender therefore Universidad EAFIT is not responsible for what the message contains.
participants (3)
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Andrés Sicard-Ramírez
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Ben Gamari
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David Feuer