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ghc 7.8

Last edited by Ben Gamari
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Release plans for GHC 7.8

Tickets

Note that anything not listed here is off Austin's radar.

https://ghc.haskell.org/trac/ghc/query?status=infoneeded&status=merge&status=new&status=patch&group=status&milestone=7.8.3

The Dynamic Story

The dynamic story is complex. Here's the breakdown:

Linux (i386) Linux (x86_64) FreeBSD OS X 10.7 (x86_64) OS X 10.8 (x86_64) OS X 10.9 (x86_64) Windows i386 Windows x86_64
Dynamic GHCi YES YES YES YES YES YES NO NO
-dynamic-too YES YES YES YES YES YES NO NO
-dynamic YES YES YES YES YES YES NO NO

  • Dynamic GHCi:

    • YES: ghci uses the system linker to link .so or .dll dynamic libraries, to avoid linker bugs. This is controlled by DYNAMIC_GHC_PROGRAMS=YES.
    • NO: ghci uses GHC's hand-written linker to link .o files.

  • -dynamic: makes GHC produce .so/.dll files rather than .o files.

  • -dynamic-too: strictly an optimization, -dynamic-too allows the compiler to build static and dynamic object files at once. This is convenient for Dynamic GHCi support.

The Windows Conundrum

  • Windows is a bit difficult right now.

    • Good news: 64bit builds work using the fancy new MSYS2 environment with a few (~6) failures!

    • Bad news: 32bit builds work well using the old environment

      • Austin confirmed the latest HEAD worked in the old 32bit environment, but not the msys2 one: the ghc-stage2.exe segfaults, and Austin hasn't tracked down why.
      • Obvious theory: msys2 environment is incorrectly configured somewhere
      • On the upside, 32bit in the old environment seems quite stable (~3 test failures,) even if make is a bit nutty.

    • It seems -dynamic is busted, as well as -dynamic-too

    • Consequently, GHCi can't be dynamically linked.

    • We're punting all three of them for the RC.

      • This leaves GHC in the same place it was before essentially (but 64bit is in a difficult spot, see #7134 (closed))

(Related but not immediately critical: we have too many DLL symbols, and are very close to the limit (#5987 (closed)). Linking also takes a long time (#8229 (closed)))

Other things

  • Austin Seipp needs to upload the primops compatibility package for 7.8. This is is easy: mostly a copy of compiler/utils/ExtsCompat64.hs into a Cabal package. See also the compatibility module page.