Multi-threaded builds exacerbate the non-determinism in ghc package ids, which
is a serious problem for libraries. Packages that define only executables,
however, should be safe to build with parallelism enabled.
Packages that don't have a Setup.hs file get to use a default version that
lives in the Nix store. By default ghc tries to put the Setup.o and Setup.hi
files in the same directory as the source file, which isn't writable. This
leads to build errors [1]. Thus, we re-direct those paths to a build-local
writable location: $TMPDIR.
Arguably, we could also use "." or copy the /nix/store/deadbeef-Setup.hs file
into the local source directory before compiling, which would work fine, too.
[1] https://github.com/NixOS/nixpkgs/issues/4851
Hydra generates a GHC closure for Darwin that for no apparent reason
contains an ancient, broken Haddock binary -- probably because of an
impurity in the build system. That bug makes those GHC binaries
unusable: <https://github.com/NixOS/nixpkgs/issues/2689>.
This likely exacerbates the non-determinism in ghc package ids, so until
that is fixed let's live with the slow builds.
This reverts commit 817c0e4144.
1) Packages formerly called haskell-haskell-platform-ghcXYZ-VVVV.X.Y.Z are
now called haskell-platform-VVVV.X.Y.Z. The latest version can be
installed by running "nix-env -i haskell-platform".
2) The attributes haskellPackages_ghcXYZ.haskellPlatform no longer exist.
Instead, we have attributes like haskellPlatformPackages."2012_4_0_0".
(The last numeric bit must be quoted when used in a Nix file, but not on
the command line to nix-env, nix-build, etc.) The latest Platform has a
top-level alias called simply haskellPlatform.
3) The haskellPackages_ghcXYZ package sets offer the latest version of every
library that GHC x.y.z can compile. For example, if 2.7 is the latest
version of QuickCheck and if GHC 7.0.4 can compile that version, then
haskellPackages_ghc704.QuickCheck refers to version 2.7.
4) All intermediate GHC releases were dropped from all-packages.nix to
simplify our configuration. What remains is a haskellPackages_ghcXYZ set
for the latest version of every major release branch, i.e. GHC 6.10.4,
6.12.3, 7.0.4, 7.2.2, 7.4.2, 7.6.3, 7.8.2, and 7.9.x (HEAD snapshot).
5) The ghcXYZPrefs functions in haskell-defaults.nix now inherit overrides
from newer to older compilers, i.e. an override configured for GHC 7.0.4
will automatically apply to GHC 6.12.3 and 6.10.4, too. This change has
reduced the redundancy in those configuration functions. The downside is
that overriding an attribute for only one particular GHC version has become
more difficult. In practice, this case doesn't occur much, though.
6) The 'cabal' builder has a brand-new argument called 'extension'. That
function is "self : super : {}" by default and users can override it to
mess with the attribute set passed to cabal.mkDerivation. An example use
would be the definition of darcs in all-packages.nix:
| darcs = haskellPackages.darcs.override {
| cabal = haskellPackages.cabal.override {
| extension = self : super : {
| isLibrary = false;
| configureFlags = "-f-library " + super.configureFlags or "";
| };
| };
| };
In this case, extension disables building the library part of the package
to give us an executable-only version that has no dependencies on GHC or
any other Haskell packages.
The 'self' argument refers to the final version of the attribute set and
'super' refers to the original attribute set.
Note that ...
- Haskell Platform packages always provide the Haddock binary that came with
the compiler.
- Haskell Platform 2009.2.0.2 is broken because of build failures in cgi and
cabal-install.
- Haskell Platform 2010.1.0.0 is broken becasue of build failures in cgi.
This reverts commit a2a398fbda. The
issue *does* still exist in GHC 7.8.2. Compiled binaries have no -rpath
into their own install directory ("$out") and thus cannot find their own
shared libraries. To work around this issue, we pass an explicit -rpath
argument at configure time. We do that only on Linux, though, because
-rpath is known to cause trouble on Darwin, which was the reason I
originally reverted that patch.
disabled by setting 'strictConfigurePhase' to 'false'
This is necessary for some packages, like dns, because cabal warns about
multiple versions of the same dependency being used, but the usage is fine,
actually, so we want the build to succeed. Packages that depend on 'doctest'
also have this issue <https://github.com/sol/doctest-haskell/issues/69>.
