This introduces the .inputDerivation attribute on all derivations
created with mkDerivation. This is another derivation that can always
build successfully and whose runtime dependencies are the build time
dependencies of the original derivation.
This allows easy building and distributing of all derivations needed to
enter a nix-shell with
nix-build shell.nix -A inputDerivation
I hate the thing too even though I made it, and rather just get rid of
it. But we can't do that yet. In the meantime, this brings us more
inline with autoconf and will make it slightly easier for me to write a
pkg-config wrapper, which we need.
The cross file is added in the `mkDerivation`. It isn't nice putting
build tool-specific stuff here, but our current architecture gives us
little alternative.
While looking at the graph of all the outputs in my personal binary
cache it became obvious that we have a lot of self references within the
package set. That isn't an isuse by itself. However it increases the
size of the binary cache for every (reproducible) build of a package
that carries references to itself. You can no longer deduplicate the
outputs since they are all unique. One of the ways to get rid of (a few)
references is to rewrite all the symlinks that are currently used to be
relative symlinks. Two build of something that didn't really change but
carries a self-reference can the be store as the same NAR file again.
I quickly hacked together this change to see if that would yield and
success. My bash scripting skills are probably not great but so far it
seem to somewhat work.
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.
Rewrite the `stripHash` helper function with 2 differences:
* Paths starting with `--` will no longer produce an error.
* Use Bash string manipulation instead of shelling out to `grep` and
`cut`. This should be faster.
A bunch of stdenv-internal variables were deleted in
1601a7fcce, but these are needed in the
fixup phase, whereas the rest are just needed for the initial work
(findInputs, etc) before the user phases.
CC @matthewbauer
There were two issues:
* builtins.getEnv was called deep into the nixpkgs tree making it hard
to discover. This is solved by moving the call into
pkgs/top-level/impure.nix
* when the config was explicitly set by the user to false, it would
still try and load the environment variable. This meant that it was
not possible to guarantee the same outcome on two different systems.
Before, we very carefully unapplied and reapplied `set -u` so the rest
of Nixpkgs could continue to not fail on undefined variables. Let's rip
off the band-aid.
A package's meta.license can either be a single license or a list. The
code to check config.whitelistedLicenses and config.blackListedLicenses
wasn't handling this, nor was the showLicense function.
These can be used to determine whether a ELF file with ELF header is an
executable or shared library.
We can't implement it in pure bash, as bash has problems with null
bytes.
