First, we need check against the host platform, not the build platform.
That's simple enough.
Second, we move away from exahustive finite case analysis (i.e.
exhaustively listing all platforms the package builds on). That only
work in a closed-world setting, where we know all platforms we might
build one. But with cross compilation, we may be building for arbitrary
platforms, So we need fancier filters. This is the closed world to open
world change.
The solution is instead of having a list of systems (strings in the form
"foo-bar"), we have a list of of systems or "patterns", i.e. attributes
that partially match the output of the parsers in `lib.systems.parse`.
The "check meta" logic treats the systems strings as an exact whitelist
just as before, but treats the patterns as a fuzzy whitelist,
intersecting the actual `hostPlatform` with the pattern and then
checking for equality. (This is done using `matchAttrs`).
The default convenience lists for `meta.platforms` are now changed to be
lists of patterns (usually a single pattern) in
`lib/systems/for-meta.nix` for maximum flexibility under this new
system.
Fixes#30902
This is a temporary workaround to make `nix-env -qa` and `nix search` ignore
broken packages as they they did before this patchset.
This patch should be reverted after `nix` gets a proper fix for this.
See NixOS/nix#1771.
This option makes `meta.evaluate` into a close approximation of the result of
evaluating `.outPath` by checking all the dependencies recursively at a cost of
2x slowdown. Note that actually evaluating `.outPath` costs some
5x-7x more because `.outPath` also computes all the hashes.
I hope this will be a temporary measure. If there is consensus around
issue #33599, then we can follow an explicit `dontCheck`, but default to
not checking during cross builds when none is given.
This pushes check-meta evaluation to derivation evaluation step, leaving all other
attributes accessible.
Before this commit:
> $ HOME=/homeless-shelter NIX_PATH=nixpkgs=$(pwd) nix-instantiate --eval --strict ./default.nix -A xen --argstr system aarch64-linux
> Package ‘xen-4.5.5’ in pkgs/applications/virtualization/xen/generic.nix:226 is not supported on ‘aarch64-linux’, refusing to evaluate.
as expected
> $ HOME=/homeless-shelter NIX_PATH=nixpkgs=$(pwd) nix-instantiate --eval --strict ./default.nix -A xen.name --argstr system aarch64-linux
> Package ‘xen-4.5.5’ in pkgs/applications/virtualization/xen/generic.nix:226 is not supported on ‘aarch64-linux’, refusing to evaluate.
> $ HOME=/homeless-shelter NIX_PATH=nixpkgs=$(pwd) nix-instantiate --eval --strict ./default.nix -A xen.meta.description --argstr system aarch64-linux
> Package ‘xen-4.5.5’ in pkgs/applications/virtualization/xen/generic.nix:226 is not supported on ‘aarch64-linux’, refusing to evaluate.
which is unfortunate since its impossible to use packages in autogenerated
documentation on all platforms.
After this commit:
> $ HOME=/homeless-shelter NIX_PATH=nixpkgs=$(pwd) nix-instantiate --eval --strict ./default.nix -A xen --argstr system aarch64-linux
still fails
> $ HOME=/homeless-shelter NIX_PATH=nixpkgs=$(pwd) nix-instantiate --eval --strict ./default.nix -A xen.name --argstr system aarch64-linux
> "xen-4.5.5"
> $ HOME=/homeless-shelter NIX_PATH=nixpkgs=$(pwd) nix-instantiate --eval --strict ./default.nix -A xen.meta.description --argstr system aarch64-linux
> "Xen hypervisor and related components (vanilla)"
4 far-reaching changes: Smaller PATH, New vars, different propagation
logic, and different hook logic
Smaller PATH
------------
`buildInputs` no longer go on the PATH at build time, as they cannot be
run when cross compiling and we don't want to special case. Simply make
a `nativeBuildInput` too if one needs them on the PATH. Fixes#21191.
Many new depedendency variables
-------------------------------
See the stdenv chapter of the nixpkgs manual. I pulled out the existing
documentation of dependency specification into a new section, and added
language for these two (and their propagated equivalents) along side
the others'.
More complex propagation logic
------------------------------
Before a propagated*XXX*Input always acted as if it was specified
directly as a *XXX*Input downstream. That's simple enough, but violates
the intended roles of each sort of dep, which has functional and not
just stylistic consequences.
The new algorithm is detailed in the manual, and ensures everything
ends up in the right place. I tried to give both an informal and formal
description, but I suspect in practice it will not make much sense
until one tries cross compiling, after which it will immediately make
sense as the only sane option.
Simplified hook logic
---------------------
Rather than `envHook` and `crossEnvHook`, whose behavior differs
depending on whether we are cross compiling or not, there is now one
hook per sort (or rather non-propagated and propagated pair of sorts)
of dependency. These new hooks have the same meaning regardless of
cross compilation. See the setup hook section of stdenv chapter of the
Nixpkgs manual for more details.
This becomes necessary if more wrappers besides cc-wrapper start
supporting hardening flags. Also good to make the warning into an
error.
Also ensure interface is being used right: Not as a string, not just in
bash.
This reverts commit eeabf85780.
This change suddenly makes tons of stdenv internals visible in
nativeBuildInputs of every derivation, which doesn't seem desirable.
E.g:
````
nix-repl> hello.nativeBuildInputs
[ «derivation /nix/store/bcfkyf6bhssxd2vzwgzmsbn7b5b9rpxc-patchelf-0.9.drv»
«derivation /nix/store/4wnshnz9wwanpfzcrdd76rri7pyqn9sk-paxctl-0.9.drv»
<< snip 10+ lines >>
«derivation /nix/store/d35pgh1lcg5nm0x28d899pxj30b8c9b2-gcc-wrapper-6.4.0.drv»
]
````
Additionally, instead of pulling them from `setup.sh`, route them via
Nix. This gets us one step closer to making stdenv be a plain attribute
set instead of a derivation.
`nix-build pkgs/top-level/release.nix -A tarball` now succeeds.
`configureFlags = null` lead to a type error, and one overrideDrv
needed to be converted to to append a configureFlags list instead of
string due to the normalization.
Thanks @vcunat for alerting me to the issues---sorry I did not catch
them before merging my own PR.
Eventually the adapter will be removed. Moved is
- Name suffix from hostPlatform
- configurePlatforms
To not cause more breakage, the default is currently [], but
eventually it will be [ "build" "host" ], as the cross adapter makes
it today.
