GHC MinGW distribution

Simon Peyton Jones simonpj at
Tue Jun 10 08:25:46 UTC 2014


We would be thrilled if you would help.

We physically include very selective chunks of MinGW in a GHC Windows distribution
- so that users don't need to install MinGW
- so that GHC doesn't break just because a user has
  a different version of MinGW than we expected
We keep these chunks of MinGW in the GHC repo (in ghc-tarballs) precisely so that we know exactly which bits to ship.

The intention is that the MinGW bits shipped with GHC are essentially invisible to the user. They just see a ghc.exe, which just happens internally to call some Mingw binaries.

But as you point out, it's not quite invisible if the GHC-compiled stuff has to be compatible in some way with stuff compiled some other way. One route is to use GHC as your C compiler (which will in turn invoke the private MinGW binary), but that probably won't work; I have learned that things are Never Simple.

Moreover, it would be great to update the MinGW bits to a more modern version.

If you can do this, fantastic.  What you need to do, I think, is
- look at what is in ghc-tarballs
- pull out selected bits of the new MinGW and use them to replace 
  what's in ghc-tarballs
- test thoroughly

I'm sure that others will be happy to help.  Do keep ghc-devs posted.  You could make a ticket and post information to it as you learn about it.  Or even a wiki page to describe the process, so that in four years time when someone wants to do the same thing, they have a guide.  Speaking of which, do search the Trac Wiki in case someone *has* already docuemented some aspects of this.

I would really like to have a Windows Strike Force who collectively take responsibility for the Windows port of GHC, if you and some others felt able to be part of such a thing.



| -----Original Message-----
| From: ghc-devs [mailto:ghc-devs-bounces at] On Behalf Of Robin
| Sent: 10 June 2014 00:46
| To: ghc-devs at
| Subject: GHC MinGW distribution
| Dear All,
| I wanted to enquire about the prospects for updating the version of
| MinGW which ships with the Windows binary distribution of GHC. The
| version included as of 7.8.2 is now several years old and in some cases
| I've found that it's incompatible with the libraries produced by newer
| versions of MinGW (as to be expected, per my understanding).
| Specifically, my HsQML binding for Qt can't be used with the libraries
| from the official Windows binary distribution of Qt 5 because the
| resulting executables crash on start-up with runtime incompatibilities.
| I'm in the process of trying to build out-of-the-box compatible Qt
| binaries against GHC's MinGW, but Qt's stated minimum requirements on
| the tool-chain version aren't encouraging. The only way I currently have
| of making this work is for users to edit their GHC settings file to
| point GHC at a version of gcc.exe from a newer MinGW (such as the one
| which ships with Qt). The fact that this seems to work is encouraging,
| but it's still a bit of a difficult process to put people through.
| I know that Windows developers are in short supply, so I would like to
| offer what assistance I can in making this happen. There appear to be
| copies of MinGW stored in the GHC repository at
| . Does the build system use
| these automatically or are they just there for reference?
| Thanks,
| --
| Robin KAY
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| ghc-devs mailing list
| ghc-devs at

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