In reply to @x10an14:matrix.org

Anyone know of a cross-compilation example that targets musl and uses rust-overlay?

I can't for the life of me figure this out. I've spent the past couple of hours trying to search and read up on it, but I feel like there's some crucial tidbits of ignorance that keep me in the dark.
All the rust docs refer to leveraging rustup, which AFAIU is kinda antheisis to the premise of Nix.

I'm finding the learning curve a bit too steep for me =/

I've attempted:
rust-toolchain.toml;

[toolchain]
targets = ["x86\_64-unknown-linux-musl", "x86\_64-unknown-linux-gnu"]

flake.nix:

  overlays = [
    (import rust-overlay)
    (self: super: {
      rustToolchain =
        let
          rust = super.rust-bin;
        in
        if builtins.pathExists ./rust-toolchain.toml then
          rust.fromRustupToolchainFile ./rust-toolchain.toml
        else if builtins.pathExists ./rust-toolchain then
          rust.fromRustupToolchainFile ./rust-toolchain
        else
          rust.stable.latest.default;
    })
  ]

And finally; cargo build --target 'x86_64-unknown-linux-musl'

I'm not able to make it work for nix build, yet I am able to make it work for cargo build --target... Here's a paste explaining my differences: https://paste.sr.ht/~x10an14/57e8d3d2014e44232692773affc74741b5776ddb

Could some kind samaritan take take a look and see if they can understand and tell me what's going on?

Thanks, I managed! Now just to figure out why I have this issue when compiling with pkgs.pkgsMusl.openssl.dev...

-> $ nix build && ldd result/bin/assign-item-to-project-field 
warning: Git tree '/home/x10an14/Documents/sr.ht/assign-item-to-project-field' is dirty
        linux-vdso.so.1 (0x00007ffe9ed98000)
        libssl.so.3 => not found
        libcrypto.so.3 => not found

Oops these replies were meant for your rustls suggestion.

I already tried pkgsStatic.openssl - but that failed during compilation of something. Gave up on that avenue before I figured out what was wrong.

Yeah, no, doesn't seem to work?

Ref:

-> $ git diff Cargo.toml && nix build && ldd result/bin/assign-item-to-project-field && cargo tree -i openssl-sys

Cargo.toml

 10 ⋮ 10 │clap-verbosity-flag = "1"
 11 ⋮ 11 │clap_complete_command = "0.3"
 12 ⋮ 12 │color-eyre = "0.6"
 13 ⋮    │graphql_client = "0.11"
    ⋮ 13 │graphql_client = { version = "0.11", features = ["reqwest-rustls"] }
 14 ⋮ 14 │log = "0.4"
 15 ⋮    │reqwest = { version = "0.11", features = ["json"] }
    ⋮ 15 │reqwest = { version = "0.11", features = ["json", "rustls-tls"] }
 16 ⋮ 16 │serde = "1"
 17 ⋮ 17 │serde_json = "1"
 18 ⋮ 18 │tokio = { version = "1", features = ["macros", "rt-multi-thread", "fs"] }
warning: Git tree '/home/x10an14/Documents/sr.ht/assign-item-to-project-field' is dirty
        linux-vdso.so.1 (0x00007fff27330000)
        libssl.so.3 => not found
        libcrypto.so.3 => not found
openssl-sys v0.9.76
├── native-tls v0.2.10
│   ├── hyper-tls v0.5.0
│   │   └── reqwest v0.11.12
│   │       ├── assign-item-to-project-field v0.1.0 (/home/x10an14/Documents/sr.ht/assign-item-to-project-field)
│   │       └── graphql_client v0.11.0
│   │           └── assign-item-to-project-field v0.1.0 (/home/x10an14/Documents/sr.ht/assign-item-to-project-field)
│   ├── reqwest v0.11.12 (*)
│   └── tokio-native-tls v0.3.0
│       ├── hyper-tls v0.5.0 (*)
│       └── reqwest v0.11.12 (*)
└── openssl v0.10.42
    └── native-tls v0.2.10 (*)

-> $ cargo tree --help | grep ' --invert'
    -i, --invert [<SPEC>]         Invert the tree direction and focus on the given package

-> $ cargo tree --invert openssl-sys
openssl-sys v0.9.76
├── native-tls v0.2.10
│   ├── hyper-tls v0.5.0
│   │   └── reqwest v0.11.12
│   │       ├── assign-item-to-project-field v0.1.0 (/home/x10an14/Documents/sr.ht/assign-item-to-project-field)
│   │       └── graphql_client v0.11.0
│   │           └── assign-item-to-project-field v0.1.0 (/home/x10an14/Documents/sr.ht/assign-item-to-project-field)
│   ├── reqwest v0.11.12 (*)
│   └── tokio-native-tls v0.3.0
│       ├── hyper-tls v0.5.0 (*)
│       └── reqwest v0.11.12 (*)
└── openssl v0.10.42
    └── native-tls v0.2.10 (*)

-> $ cargo tree --invert openssl
openssl v0.10.42
└── native-tls v0.2.10
    ├── hyper-tls v0.5.0
    │   └── reqwest v0.11.12
    │       ├── assign-item-to-project-field v0.1.0 (/home/x10an14/Documents/sr.ht/assign-item-to-project-field)
    │       └── graphql_client v0.11.0
    │           └── assign-item-to-project-field v0.1.0 (/home/x10an14/Documents/sr.ht/assign-item-to-project-field)
    ├── reqwest v0.11.12 (*)
    └── tokio-native-tls v0.3.0
        ├── hyper-tls v0.5.0 (*)
        └── reqwest v0.11.12 (*)

For completeness:

-> $ git diff Cargo.toml && echo -e "# Git diff of Cargo.toml above\\n---\\n# \`nix build\` and \`ldd\` invocation below" && nix build && ldd result/bin/* 

Cargo.toml

 10 ⋮ 10 │clap-verbosity-flag = "1"
 11 ⋮ 11 │clap_complete_command = "0.3"
 12 ⋮ 12 │color-eyre = "0.6"
 13 ⋮    │graphql_client = "0.11"
    ⋮ 13 │graphql_client = { version = "0.11", features = ["reqwest-rustls"] }
 14 ⋮ 14 │log = "0.4"
 15 ⋮    │reqwest = { version = "0.11", features = ["json"] }
    ⋮ 15 │reqwest = { version = "0.11", features = ["json", "rustls-tls"] }
 16 ⋮ 16 │serde = "1"
 17 ⋮ 17 │serde_json = "1"
 18 ⋮ 18 │tokio = { version = "1", features = ["macros", "rt-multi-thread", "fs"] }
# Git diff of Cargo.toml above
---
# `nix build` and `ldd` invocation below
warning: Git tree '/home/x10an14/Documents/sr.ht/assign-item-to-project-field' is dirty
        linux-vdso.so.1 (0x00007ffef59a3000)
        libssl.so.3 => not found
        libcrypto.so.3 => not found