Don't rely on unstable flags.

[dpc]

Fix #100

[dpc]

I tested it with beta and stable and on my little project seems to work. Other than this I have no idea what I'm doing.

[nmattia]

Thanks! @basvandijk do you remember why we used --out-dir and not CARGO_TARGET_DIR? I know there was a reason, but right it escapes me...

[nmattia]

Ah, I think I knew. The difference is explained here: rust-lang/cargo#5203

The --out-dir parameter is only for final artifacts, and not intermediary results like rlibs (I think). Can you check the final build size with and without your changes?

[dpc]

CARGO_TARGET_DIR — Location of where to place all generated artifacts, relative to the current working directory. See build.target-dir to set via config.

https://doc.rust-lang.org/cargo/reference/environment-variables.html

Is it a problem if everything goes into the out dir?

Edit: Oh. The build size, you say... :(

[dpc]

Would it be OK if we just delete needless stuff from the output dir? I mean - it's not all that difficult. All the subdirs, and then bunch of .d and .rmeta files, and job done?

[dpc]

BTW. I have no idea why, but I'm building my Rust project under a special name (just to make sure I am looking at the right output):

~/l/dotr (master)> find /nix/store/ | grep dotrx
/nix/store/f6x9qjq27ixjdlb38g1fdc95rc7157vr-dotr-0.4.0/bin/dotrx

No other files than the binary. No idea why.

[nmattia]

Mh ok that's odd. Maybe that actually works since the top-level derivation only builds the executable? what if you set single-step to true so that everything is built in one derivation?

[dpc]

Weird. Same? I've changed the name to dotrxx now.

[I] 08-20 11:41 dpc@futex ~/l/dotr (master)> find /nix/store/y9r0lhv3q8mkk3vxlrisjy38c1dxwmlx-dotr-0.4.0
/nix/store/y9r0lhv3q8mkk3vxlrisjy38c1dxwmlx-dotr-0.4.0
/nix/store/y9r0lhv3q8mkk3vxlrisjy38c1dxwmlx-dotr-0.4.0/bin
/nix/store/y9r0lhv3q8mkk3vxlrisjy38c1dxwmlx-dotr-0.4.0/bin/dotrxx

previous one (no singleStep), to double check.

[I] 08-20 11:41 dpc@futex ~/l/dotr (master)> find /nix/store/f6x9qjq27ixjdlb38g1fdc95rc7157vr-dotr-0.4.0
/nix/store/f6x9qjq27ixjdlb38g1fdc95rc7157vr-dotr-0.4.0
/nix/store/f6x9qjq27ixjdlb38g1fdc95rc7157vr-dotr-0.4.0/bin
/nix/store/f6x9qjq27ixjdlb38g1fdc95rc7157vr-dotr-0.4.0/bin/dotrx

[dpc]

Is it because of

    # The value is written to the `cargo_bins_jq_filter` variable.                                                                           
    copyBinsFilter = attrs0.copyBinsFilter or                                                                                                
      ''select(.reason == "compiler-artifact" and .executable != null and .profile.test == false)'';                                         

?

So there is already a redundant mechanism for picking the important stuff from out, it seems.

[nmattia]

Well then! if it breaks anything, we'll revert and add a test :)

[nmattia]

Actually I just reverted the commit. I realized that you were setting CARGO_TARGET_DIR locally, for the build only, meaning that cargo test, clippy, doc, etc will be rebuilding from scratch, since they'd revert to the default target/!

[dpc]

Does it mean I should add that flag into other places as well?

[nmattia]

Yes I think you can export it like so:

naersk/build.nix

Line 241 in df71f5e

export RUST_TEST_THREADS="''${RUST_TEST_THREADS:-$NIX_BUILD_CORES}"

Thanks!

[dpc]

I am completely confused what am I doing. I don't understand why exactly it was reverted and what is the problem in the first place. :)

Is is that when using nix develop or something and having ./target local to the workdir, is supposed to be used when doing nix build .# or something?

[nmattia]

I guess I could have been clearer! Here you set CARGO_TARGET_DIR for the cargo build command. The CARGO_TARGET_DIR specifies where to put all the build outputs, but also all the intermediary outputs. The default is ./target. This means that other commands like cargo test or cargo clippy will still use ./target, and won't benefit from anything built by CARGO_TARGET_DIR! So either we specify CARGO_TARGET_DIR for all commands, or we don't specify it at all and use target instead of out as the expected output directory. Hope this clarifies :)