In reply to @rhelmot:matrix.org
nix-repl> builtins.currentSystem
"x86_64-linux"

nix-repl> pkgsCross.x86_64-freebsd.pkgsTargetTarget
{
__raw = true;
recurseForDerivations = false;
stdenv = { ... };
}

nix-repl> pkgsCross.x86_64-freebsd.pkgsTargetTarget.stdenv
{
cc = «derivation /nix/store/nhj8bgij919zkfb9f5z3h11gh3gc3r1f-x86_64-unknown-freebsd-clang-wrapper-19.1.6.drv»;
}

In reply to @lily:lily.flowers
yeah from what i understand you can't pkgsTargetTarget from a cross set, it just isn't supported/implemented. what you're seeing seems to be just this "fake" set after bootstrap stages used for a compiler hack, defined here: https://github.com/NixOS/nixpkgs/blob/cd0883f61c95f321983c0d18f53040b8c76fc263/pkgs/stdenv/booter.nix#L142-L163

Hi, Happy New Year!

Using pkgs.pkgsCross, I can compile a package from nixpkgs for another platform. For example:

# nix-build '<nixpkgs>' -A pkgs.pkgsCross.aarch64-multiplatform.hello

I have a local repository with a package. For example, let’s say it’s a simple hello world.

default.nix:

{ pkgs ? import <nixpkgs> { } }:

{
    myhello = pkgs.callPackage ./pkgs/myhello { };
}

However, I can't build it the same way:

# nix-build -A pkgs.pkgsCross.aarch64-multiplatform.myhello          
error: attribute 'pkgs' in selection path 'pkgs.pkgsCross.aarch64-multiplatform.myhello' not found

I can change pkgs.callPackage in default.nix to pkgs.pkgsCross.aarch64-multiplatform.callPackage. Then the package builds:

# nix-build -A myhello
this derivation will be built:
  /nix/store/3mbcklrdg4dc90qg47fvakv6zv9gwqm2-myhello-1.0-aarch64-unknown-linux-gnu.drv
...

How can I properly test cross-compilation without adding the repository via a channel or flake?
I’d like to test building for different platforms without modifying nix files, as if the package were part of nixpkgs.

Hi, Happy New Year!

Using pkgs.pkgsCross, I can compile a package from nixpkgs for another platform. For example:

# nix-build '<nixpkgs>' -A pkgs.pkgsCross.aarch64-multiplatform.hello

I have a local repository with a package. For example, let’s say it’s a simple hello world.

default.nix:

{ pkgs ? import <nixpkgs> { } }:

{
    myhello = pkgs.callPackage ./pkgs/myhello { };
}

However, I can't build it the same way:

# nix-build -A pkgs.pkgsCross.aarch64-multiplatform.myhello          
error: attribute 'pkgs' in selection path 'pkgs.pkgsCross.aarch64-multiplatform.myhello' not found

I can change pkgs.callPackage in default.nix to pkgs.pkgsCross.aarch64-multiplatform.callPackage. Then the package builds:

# nix-build -A myhello
this derivation will be built:
  /nix/store/3mbcklrdg4dc90qg47fvakv6zv9gwqm2-myhello-1.0-aarch64-unknown-linux-gnu.drv
...

How can I properly test cross-compilation without adding the repository via a channel or flake?
I’d like to test building for different platforms without modifying nix files, as if the package were part of nixpkgs.