Before, we'd always use `cc = null`, and check for that. The problem is
this breaks for cross compilation to platforms that don't support a C
compiler.
It's a very subtle issue. One might think there is no problem because we
have `stdenvNoCC`, and presumably one would only build derivations that
use that. The problem is that one still wants to use tools at build-time
that are themselves built with a C compiler, and those are gotten via
"splicing". The runtime version of those deps will explode, but the
build time / `buildPackages` versions of those deps will be fine, and
splicing attempts to work this by using `builtins.tryEval` to filter out
any broken "higher priority" packages (runtime is the default and
highest priority) so that both `foo` and `foo.nativeDrv` works.
However, `tryEval` only catches certain evaluation failures (e.g.
exceptions), and not arbitrary failures (such as `cc.attr` when `cc` is
null). This means `tryEval` fails to let us use our build time deps, and
everything comes apart.
The right solution is, as usually, to get rid of splicing. Or, baring
that, to make it so `foo` never works and one has to explicitly do
`foo.*`. But that is a much larger change, and certaily one unsuitable
to be backported to stable.
Given that, we instead make an exception-throwing `cc` attribute, and
create a `hasCC` attribute for those derivations which wish to
condtionally use a C compiler: instead of doing `stdenv.cc or null ==
null` or something similar, one does `stdenv.hasCC`. This allows quering
without "tripping" the exception, while also allowing `tryEval` to work.
No platform without a C compiler is yet wired up by default. That will
be done in a following commit.
I think those deps could be made to build, but I didn't want to get
bogged down investigating further. "Use flags" are always a good thing,
so this is fine for now.
The provided patch doesn't apply cleanly on sundials_3 (no
SundialsTesting.cmake, SundialsAddTest.cmake containing trailing
whitespaces inside context), so for now we just disable tests for
sundials_3 - scikits-odes plans to move to sundials 4 anyways - see
https://github.com/bmcage/odes/pull/106.
John Ericson
Craig Hall
mb
John Ericson
Jörg Thalheim
worldofpeace
Jörg Thalheim
Jan Tojnar
zimbatm
Frederik Rietdijk
Domen Kožar
Marek Mahut
Peter Hoeg
Frederik Rietdijk
Matthieu Coudron
Ben Wolsieffer
Orivej Desh
volth
Florian Klink
Dominic Steinitz