- ghc-devs - Haskell.org

Title index
by Simon Peyton Jones 07 Jan '21

07 Jan '21

Ben On GHC's wiki home page<https://gitlab.haskell.org/ghc/ghc/-/wikis/home> we have Title Index<https://gitlab.haskell.org/ghc/ghc/wikis/index> over in the right margin. I thought the title index was auto-generated. But it doesn't contain this page<https://gitlab.haskell.org/ghc/ghc/-/wikis/Functional-dependencies-in-GHC>. What's up? Thanks Simon

2 1

Debugging annotation machinery
by Phyx 04 Jan '21

04 Jan '21

Hi, I am changing the hashing algorithm used to create Fingerprints but somehow the annrun01.hs test has started failing and I don't quite understand why. >From what I can tell the failure happens during deserialization but the module itself is still found. The calls findGlobalAnns deserializeWithData target seem to return nothing. Calling ~/ghc/inplace/bin/ghc-stage2.exe --show-iface Annrun01_Help.hi shows that GHC itself understands the module fine though. Does someone have an idea why deserialization might be failing? but also how does one debug this? Almost none of the structures have a Show or Outputable instance... Thanks, Tamar

3 2

Nominations close Jan 11th for the Haskell Foundation Board
by Simon Peyton Jones 04 Jan '21

04 Jan '21

Friends Happy new year! The closing date for self-nominations for membership of the Board of the Haskell Foundation<https://haskell.foundation/> is in just under a week: Monday January 11th 2021 The Haskell Foundation is a new non-profit organisation that seeks to articulate the benefits of functional programming to a broader audience, to erase barriers to entry, and to support Haskell as a solidly reliable basis for mission-critical applications. The Board provides the strategic leadership for the Foundation, including its goals, governance, finances, and staff. Membership of the Board is a key leadership role, not an honorary appointment. The Call for Nominations<https://haskell.foundation/board-nominations/> gives more details. Please do consider nominating yourself, or encouraging a suitable (but perhaps modest) colleague to do so. The HF needs a strong Board, and that means strong nominations. Thanks! Please do forward this message on social media or elsewhere. Simon Peyton Jones

1 0

Interruptible foreign calls, part 2
by David Feuer 04 Jan '21

04 Jan '21

Another issue is that (as the recently expanded documentation shows), an `interruptible` foreign call is not actually an "interruptible operation" in the sense used in Control.Exception. To make it so, the caller has to manually call `allowInterrupt`. Or, in the single-threaded runtime, has to call `interruptibleYield`. So ... they have to make a foreign call to `rts_isThreaded` and then use the result to figure out how to deliver a potential exception. What a terrible user experience! Why not bake the "deliver exceptions" part into the FFI code for `interruptible` calls? This stuff has been documented so very recently (not in any released GHC) that I don't imagine much will break if we make these changes.

1 1

Interruptible foreign calls and uninterruptibleMask
by David Feuer 04 Jan '21

04 Jan '21

As I understand it, `interruptible` foreign calls aren't affected by the masking state at all. It seems to me that they really should respect `uninterruptibleMask`. In particular, within the scope of `uninterruptibleMask`, if an exception arrives and successfully interrupts the foreign call, then the `allowInterrupt` call will not actually deliver the exception, and the failure/EINTR loop (e.g., throwIfMinus1Retry) will just perform the interrupted call again. How I think it should work is that an `interruptible` foreign call should act exactly like a `safe` foreign call in the scope of `uninterruptibleMask`. Does this make sense? If so, does it need a GHC proposal?

1 0

ghcs-nix: An archive of GHC derivations
by Ben Gamari 03 Jan '21

03 Jan '21

Hi all, As a NixOS user, I have in the past found that I need an older GHC release that is no longer available (or not yet available) in nixpkgs. While mpickering's old-ghc-nix [1] conveniently allows standard GHC binary distributions to be adapted for use under NixOS, I have found that it is less than reliable when building later projects [2]. For this reason, I have started collecting a set of nix expressions for building GHC versions all the way back to GHC 8.4.1 and extending up to GHC 9.0.1-rc1. In addition, there is a binary cache with pre-built binaries (complements of Cachix) here [3]. I intend on continuing to add new releases to this as needed. I hope others also find this helpful. Cheers, - Ben [1] https://github.com/mpickering/old-ghc-nix [2] https://gitlab.haskell.org/ghc/ghc/-/issues/19144 [3] https://app.cachix.org/cache/ghc

1 1

can't get raw logs -- server down?
by Richard Eisenberg 24 Dec '20

24 Dec '20

Hi devs, I have a failing CI run at https://gitlab.haskell.org/ghc/ghc/-/jobs/533674 <https://gitlab.haskell.org/ghc/ghc/-/jobs/533674>. I can't repro the problem locally, so I wanted to see the raw log. But clicking the raw log button (leading to https://gitlab.haskell.org/ghc/ghc/-/jobs/533674/raw <https://gitlab.haskell.org/ghc/ghc/-/jobs/533674/raw>) gets nothing. It looks like a server is down. Help? Thanks! Richard

2 2

Troubles when building ghc
by Neophytos Michael 24 Dec '20

24 Dec '20

I am having some trouble building ghc on ubuntu. I have ghc 8.8.4 installed on the machine. I pulled from the main repository and followed the instructions here: https://gitlab.haskell.org/ghc/ghc/-/wikis/building/hadrian Building with: ./hadrian/build -j it builds for a long time until it finally fails with the message below. I would appreciate some advice on how to fix this. Thank you, Neo =========================== Exit code: 1 Stderr and Stdout: _build/stage1/compiler/build/GHC/Parser/Lexer.hs:3495:3: error: Variable not in scope: int16ToInt# :: Int# -> Int# | 3495 | int16ToInt# | ^^^^^^^^^^^ _build/stage1/compiler/build/GHC/Parser/Lexer.hs:3520:3: error: Variable not in scope: int32ToInt# :: Int# -> Int# | 3520 | int32ToInt# | ^^^^^^^^^^^ =========================== On that line (in Lexer.hs) we see: #if __GLASGOW_HASKELL__ >= 901 int16ToInt# #endif (indexInt16OffAddr# arr off) #endif so we are in the "then" clause and somehow "int16ToInt#" is nowhere to be found. -- Neo

3 3

Fat interface files?
by Ben Gamari 21 Dec '20

21 Dec '20

Hi Edward, While chatting with the ghc-ide folks recently I realized that it would be useful to be able to preserve Core such that compilation can be restarted (e.g. to be pushed down the bytecode pipeline to evaluate TH splices). As I recall this is precisely what you implemented in your "fat interface file" work. Do you recall what the state of this work was? Do you have a branch with last-known-good work? Do you recall any tricky questions that remained outstanding? Cheers, - Ben

5 6

[ANNOUNCE] Glasgow Haskell Compiler 8.10.3 released
by Ben Gamari 20 Dec '20

20 Dec '20

Hello all, The GHC team is happy to announce the release of GHC 8.10.3. Source and binary distributions are available at the usual place: https://downloads.haskell.org/ghc/8.10.3/ GHC 8.10.3 fixes a number of issues in present in GHC 8.10.2 including: * Numerous stability improves on Windows * More robust support for architectures with weak memory ordering guarantees (e.g. modern ARM hardware). * GHC can now split dynamic objects to accomodate macOS' RPATH size limitation when building large projects (#14444) * Several correctness bugs in the new low-latency garbage collector * Many, many other bug-fixes Note that at the moment we still require that macOS Catalina users exempt the binary distribution from the notarization requirement by running `xattr -cr .` on the unpacked tree before running `make install`. This situation will hopefully be improved for GHC 9.0.1 with the resolution of #17418 [1]. Cheers, - Ben [1] https://gitlab.haskell.org/ghc/ghc/issues/17418

3 3